GPS World

Author: Tim Burch

  • GNSS and the Surveyor: Take Me to School

    The adaptation of GPS for civilian use is the single greatest step taken by  the land surveyor, more specifically the advance to  real-time kinematic networks. Now unmanned aerial vehicles enable data collection in places thought impossible previously, and laser/LiDAR scanners are on the horizon as the next game-changer. But how did we get here? An understanding of our history can be help us prepare for the future.

    The land surveyor has been practicing this occupation since man first claimed rights to physical property. In similar fashion with almost all other professions and trades, forward progress in knowledge and technology has increased educational requirements for even the most mundane of surveying tasks. An environment in which a simple survey is completed by manual measurements and depicted on a hand-drawn plat still exists but will continue to decrease as technological acceptance and governmental requirements become increased. The challenge will be a continual advancement to educate the surveying community as a whole.

    Today, the average age of the professional land surveyor approaches that of a sexagenarian (no worries, it’s just a fancy word for being in your sixties). Here’s a rundown of how we got there:

    Boots on the Ground

    In a previous article, I wrote of my journey to becoming a professional land surveyor (GPS World November 2015) and how it was possible for a high school graduate to be introduced to this wonderful profession with little to no formal training. Even though my introduction into land surveying started in the early 1980’s, it was still during what I refer to the early “high tech” surveying era. While electronics were evolving the surveying industry from the late 1960’s to my beginning days, it didn’t change the career path for the surveyor.

    At the time of my surveying opportunity, an entry level employee didn’t require the knowledge of higher level math, science and geodesy to gain a position as a chainman on a three-man survey crew. At a minimum, the employee was instructed to hold the measuring tape (known as the “chain”) at specific locations as directed by the survey party chief. The employee also was utilized as a pack mule to carry equipment and staking materials, so physical conditioning and stamina were much more important characteristics that knowledge of the profession.

    Over time (and usually through employee attrition), the chainman could learn to run the surveying equipment, which included transits, levels, and theodolites. Total stations with integrated electronic distance meters (EDM) were just becoming mainstream during my early days as an instrument person but little additional knowledge was necessary other than on-the-job training. The benefit of the EDM allowed the survey crew to measure further and faster than previous manual methods.

    An additional benefit of the total station was the digital readout of the horizontal and vertical angles and the elimination of the time-consuming need of reading the angular verniers.  These electronic advancements were great but didn’t affect the procedures for calculating survey figures and boundary analysis; they only increased the productivity of the field crew.

    Once an instrument man became more knowledgeable in the math and processes of land surveys, it was possible to advance further as a party chief. This path included many days on construction sites, hand calculating staking points and alignments, squaring up buildings and running traverses under the direction of a party chief, who in many cases, had become a professional land surveyor by these methods as well.

    Most of the knowledge obtained for career advancement was still on-the-job, but now also included some office tasks to compute boundary calculations and staking calculations through simple geometry/trigonometry means. Not rocket science but still required a good head for math and problem solving; this step also provided a potential career roadblock. This meant an occupational ceiling for some and advancement for others.

    Most of those who continued to advance were the ones with the stronger mathematical aptitude and capability to evolve with the knowledge they were gaining during their experiences as an apprentice land surveyor. The success of these future professional land surveyors depended greatly on successful mentoring capabilities of his/her previous supervisors. For those fortunate enough to learn under a great mentor, many more facets of the profession were introduced to them to gather experience. They were provided with time and care to explain and demonstrate proper methods and procedures for many surveying tasks, along with an example of how paying it forward helps everyone in the process.

    There are those, however, that received limited personal and professional training from their supervisors. These supervisors/managers possessed little experience in formal education or training methods. While these superiors excelled well enough to pass the licensing requirements at the time, the fast-paced movement of the surveying profession has left them in the dust. It is also these individuals who lack the necessary knowledge to successfully train and mentor the next generation of professional land surveyors.

    Old School versus New School

    The point here is that all of this was possible for the “old world” way of surveying. Several of my professional land surveyor contemporaries came up through this pathway of apprenticeship and mentoring with little to no formal education or training, yet have succeeded in business very well for themselves. But I caution you; they are not the norm. This minority of forward thinking professional land surveyors are the ones who remain visible in our business environment and continue to push themselves toward improvement for personal and professional gain.

    Where does this leave everyone else? Like so many other professions that have existed for centuries, the system of learning the craft of land surveying is based upon being self-serving. A historical look at the profession will reveal a long list of generational lines of land surveyors (yours truly included…) and have passed down the occupation somewhat like a family crest. But like so many vocations that get passed down like a family heirloom, if the means and methods of the occupation don’t progress with the times, it will eventually falter.

    The earlier example of the career of the land surveyor was possible until the early 1990’s; that’s when the electronic modernization of our profession picked up steam and the survey equipment manufacturers began revolutionizing our measuring and data collection methods. Couple the hardware enhancements with the boost in drafting capabilities of several drafting packages and that starts us down the road of needing staff with more educational requirements. Because of the advancements in both the field and office tasks of land surveying, we must look at each to understand how technology must be embraced to succeed as a profession.

    Not Your Father’s Transit & Chain (or Theodolite or Total Station…)

    I believe the field portion of the land surveying revolution started in the mid-1990’s with the rapid change in technology. Geodimeter led the conventional instrument innovation with servo-driven theodolites and robotic total stations that increased field productivity along with reducing errors. Along with the advancement of data collectors, these improvements greatly modernized a manual method of locating information. It also gave surveying firms an opportunity to reduce the number of staff members necessary on a field crew and spread their work out to more customers.

    The continuing improvement of the software on the data collector also made it more user friendly but also providing a “dumbing down” of the way the information is collected. While the data collection is now more efficient, the overall calculation process hasn’t changed much. But when this information is incorporated into various datums and coordinate systems, it gets much more complicated. We’ll cover this area more later.

    As stated in my previous articles, it is my opinion that the adaptation of the global positioning system created by the United Stated Department of Defense for civilian use is the single greatest improvement for the land surveyor (GPS World May 2016), more specifically the advancement to the real-time kinematic network. Couple this now with the exploding market of the unmanned aerial vehicle (UAV) with GNSS location capability, the surveying community now can collect data in places though impossible previously.

    The use of GNSS is a big part of that equation (no pun intended) and having the right balance of education and experience with its use will be key to our profession’s success. The continued to use of all facets of GNSS by surveyors worldwide will require the need for more responsible field staff. They will need to have the proper education and experience to comprehend the technology and calculations behind the data.

    I would be remiss if I didn’t mention laser/LiDAR scanners as tools for surveyors. There are companies who utilize these devices on a regular basis but they haven’t become the game changer like other technologies. These will come more into play as technology makes them smaller and the price point for entry into potential purchase is more affordable. The learning curve for processing the field data in point clouds is long and tedious but will evolve like everything else.

    It’s Always Warm and Dry in the Office

    Equally as important requiring proper training, education and mentoring are the land surveying tasks completed by office staff. As I stated in the opening paragraph, the norm used to be hand-drafted maps and plats depicting the results of field surveys from the notes of the party chief. Many drafters came through high school vocational programs and were hired directly after graduation. Simple angles, distances and direct measurements between entities were easy to portray and didn’t take much training. The introduction of the personal computer in the late 1970’s/early 1980’s also brought various platforms of computer-aided drafting (CAD) so another level of training was now necessary to learn both the software and the computer. Early versions were simplistic and mostly line-based but as technology increased the capability, it become more clear that a high school graduate didn’t have enough formal training to keep up with it.

    In addition to the drafting packages, computation software has become increasingly complex. These systems have developed into incredibly capable programs with a multitude of surveying solutions. This category includes aerial photography rectifying systems, point cloud manipulation and control network planning/computation systems that were only available previously on mainframe computers. While they are user friendly, they are well above the general education level of the high school graduate. The requirement to stay pertinent in the surveying environment must be centered around education.

    This Is Supposed to Be about GPS; How Do All These Things Fit In?

    I wrote in my last column regarding geolocation and how relied upon it has become in our society, (GPS World January 2017), and the land surveying community is no exception. The story here becomes about how quickly we can train the entire surveying profession to recognize the importance of location in our vocation or get left in the dust.

    It used to be location only mattered to explorers and mappers. Even with the creation of the latitude/longitude system, it was embraced more for the those who were traveling and giving directions to those planning to do so. Early surveys only related to surrounding properties and didn’t give much mind to specifically where it was located on the face of the earth. The surveys and related legal descriptions relied on physical monuments and avoiding hindrances versus actual measurements. That’s one reason why in the surveyor’s Rule of Construction that monuments carry significantly more weight that distance or direction in a legal description. The early settlers of the American Colonies relied on this system for conveyance of properties.

    It was only when the United States wanted to sell the lands gained from the Revolutionary War and Louisiana Purchase did they come up with a system for dividing the land. The Land Ordinance of 1785 was the beginning of the Public Land Survey System (PLSS) with the Surveyor General sending his staff westward to begin the task of establishing the sectional system.

    Fast forward to the 20th century and the rapid expansion of civilization worldwide. In the post-WW2 timeframe, our world was going places. Highway systems were increasing and the need to map it all was becoming more important on much larger scales. These entities charged with this mapping needed a much bigger method of planning and charting to depict where information was being located. The implementation of state plane coordinate systems was utilized to help with this task but involved high-order surveying along with brain-numbing geodesy. Very few individuals and firms were capable of doing this work but it provided a needed baseline for future endeavors.

    Fast forward to the past 20 years and think of the technological explosion of geolocation in the surveying and engineering fields. What used to be simple plat and plans has become a georeferenced dataset relied upon by clients, contractors, governing bodies and our firms. There are many geographical information systems in place now (from cities/counties/states down to rural utility companies) that all rely on geolocation. It would be easy to sit back and state I’m just a surveyor and this geolocation thing doesn’t come across my radar, but I would be greatly mistaken. Geolocation is an important factor of my profession and must be considered for almost all of my work going forward.

    Education Is the Key

    The professional land surveyor is uniquely qualified to provide accurate measurement for platting and mapping purposes. Our main focus throughout history has been to provide guidance and knowledge on boundary matters worldwide. Our background, knowledge and experience is not only in the physical location of the boundary but of the legal precedent and standing within the court system. Only the professional land surveyor can provide the legal opinion of where a boundary line lies; a judge or jury are not permitted to do that under law. The judge can rule whether to accept your opinion as fact but cannot make the determination themselves. We have an incredible duty and responsibility to the public; now we have the opportunity to instill more trust from them regarding geolocation.

    These statements are not intending to water down the importance of any of the Rules of Construction for surveys. It is intended to bring it in a brighter light so that surveyors see they have another role to fill, and that is the role of providing locations for the world in a spatial context. All of those tasks we provide can now be referenced in another view; data location in relation to the world.

    The professional land surveyor and their use of GNSS provides the basis of all real and potential mapping. Our inherent background in geodesy, technology and analysis of survey data leads the way as promoting our capability as the geolocation experts. While I still believe that conventional instruments will be utilized for a significant portion of our work, it will be the GNSS portion that will further define us as the experts in geolocation.

    All surveyors, both existing and future ones, need to get on board and embrace the future. This means additional education for us old timers along with planting the seeds in the junior high and high school age students who don’t know what a surveyor is or does. It means supporting the programs that train future surveyors; from the Boy Scouts through the collegiate level.

    Here is where the big difference in land surveying from past generations to now lies: education. I was fortunate enough to have started during a generation that allowed me to gain the necessary on-the-job education and training to become a professional land surveyor. I will also be the first to tell you that path is not the proper one for today’s surveying environment. Higher level math, science, and surveying training topics along with specific knowledge of geodesy, GNSS concepts, and environmental conditions are among the necessary tools for becoming a successful professional land surveyor in today’s world.

    Because of the family and financial barriers to formal schooling, there is a movement to roll back the educational requirements for professional land surveyors. I’m here to state for the record that surveying is much harder than when I began my career, so I can’t imagine trying to break into the profession now without the proper formal training. Just as many other occupations have need to adapt to stay current, the surveying profession need to do the same. There is too much at risk to not properly train our staffs to not just operate the equipment and software but to understand the concepts and results that are gained by it.

    While I became interested in land surveying for different reasons, my focus on geolocation as a subset of my boundary knowledge has me more energized for our profession. It is this enthusiasm that I ask that you help me spread to the world but also help provide the education and guidance that will be necessary for these young future professionals. In the end, the professional land surveyor through the use of GNSS can lead the charge with geolocation. All it takes is the proper education, training and guidance; after that, everything is easy.

  • Geolocation and the surveyor: Looking back to the future

    The surveyor has been known throughout history for many things: part expert measurer, part historian, part lawyer and part geographer. These attributes have led the surveyor to become a trusted member of the mapping community, on both the public, and private sides.

    Through the use of technology and associated mapping knowledge, the surveyor has provided the base layer for almost all physical ties of modern-day mapping commonly known as geolocation.

    The term has become a common word in today’s lexicon and is defined as follows:

    The physical location of an object in the world, which may be described by degrees of longitude and latitude or by a more identifiable place such as city or residence.

    Modern GPS receivers have allowed the surveyor to establish positions of important land and governmental monuments throughout the world. However, as technology has moved forward and introduced faster and cheaper ways to utilize GPS measurements with many electronic devices, applications for its use has expanded greatly as well.

    Recent uses of technology and the lower cost of entry into the geolocation world, however, is forcing governmental agencies to review uses of this data and potentially restrict its use due to privacy concerns. Let’s first review how we got here:

    Maps: Windows on the world

    Mapping has been part of civilization since the beginning of time. Early man marked out his discoveries and territorial limits on cave walls and flat rock surfaces. The invention of papyrus in the mid-2500 B.C. by the early Egyptians revolutionized how mapping data was created and retained. Keeping track of what lands had explored and being able to pass along this information provided the early incentive for map makers but crude depictions soon gave way to scientists and historians developing methods to accurately create the world around them.

    Introduction of cartography

    The art and science of mapmaking started as early as the Babylonian era, producing the first versions depicting a flat earth. The biggest revolutionary strides were by Greek philosophers Aristotle and Ptolemy several centuries later with the introduction to depicting the Earth as round and not flat per previous beliefs. With larger expeditions headed off into oceans and on to foreign lands to seek out new worlds, cartography became more important not in just recording history but accurately depicting the world around us for future exploration.

    By the 15th century, hand-drawn maps were being slowly replaced by printing procedures using wooden blocks to ease duplication. It was also during this time that new versions of the Earth were being created to present it as truly spherical and depict the “New World” findings of Columbus and fellow explorers.

    The next big enhancement to world mapping occurred in the mid-16th century when a cartographer named Gerardus Mercator of Belgium determined that our spherical Earth could be mapped by using a cylindrical projection to establish accurate latitude and longitude lines on a flat map. His projection method is still used today and is the basis of many more enhancements to world measurement systems made well into the 17th, 18th and 19th centuries in conjunction with extensive exploration and thorough record keeping.

    Modern mapping and the geographical information system

    The 20th century introduced the scientific world to several major inventions, with the electronic computer among the biggest ones. During the 1960s, Canada was leading the way with the development of a layer-based geographical information system (GIS), with the U.S. Census Bureau following closely behind.

    This race to establish GIS dominance led to significant enhancements in mapmaking capability; more specifically, the ability to collect and display large amounts of data in a graphical form. By combining existing tax mapping with aerial photography, utility information and a state-plane coordinate system, local GIS databases began to appear but at a significant cost and effort to both the government agency and parties that wanted to use the information.

    Harvard Laboratory Computer Graphics is credited with the creation of vector-based computer graphic in the mid-1970s that allowed the visualization of GIS data through electronic means. The late 1970s/early 1980s also introduced the personal and small computer systems and allowed many more opportunities to begin working with GIS databases.

    Esri opens for business

    We were also introduced to a little company that started in 1969 in California as a land-use consulting firm, which would end up dominating the GIS software world: Esri. Jack and Laura Dangermond founded the company to better organize geographic and development data for future planning. Little did they know that Esri would eventually become the GIS juggernaut it is today.

    By the late 1990s, computer companies with large resources began to see the possibilities of large-scale databases of geographical information along with high-resolution aerial and satellite photography. Microsoft was the first one to offer an online service when it combined current and historical U.S. Geological Survey orthorectified photography to create Terraserver, with more than 2 terabytes of georeferenced data, in 1997.

    This was closely followed a small group named Keyhole, which utilized the original Terraserver data as its framework. As this company expanded and the service grew, an upstart search engine firm called Google bought the company and turned the entire site into the early version of Google Earth. The rest is history.

    Surveyor’s role in geolcoation

    The late 1990s also brought significant enhancements to real-time kinematic (RTK) equipment for the surveyor and the ability to easily produce data within a variety of coordinate systems for use in GIS. (See my earlier column for additional information.) It is also through the survey world that an incredible network of existing static monuments and continuous operating reference stations (CORS) exist to allow the high-accuracy measurement of the precise location of any type of dataset.

    Many of these monuments were installed in historical or remote places that were deemed “safe” from being destroyed by future improvements or developments. It is this marriage of high-accuracy equipment and extensive network of survey monuments — along with the education, training and working knowledge of measurement and coordinate systems — that geolocation of existing features has become a surveyor’s specialty.

    Access to this information and monuments is paramount to our profession as we would be limited greatly by eliminating the ability to utilize and reference them.

    Not all who wander are lost

    Because of the technology and miniaturization of GPS-capable devices, location capable electronics has become a multi-billion-dollar industry. It is almost impossible to not have a device with you at all times that will know where you are and how to get where you want to go.

    Everything from cars to phones and computers to fitness trackers and watches has a GPS receiver to assist and track your every move. But it’s not just the GPS receivers that have revolutionized our world today; a big part of the geolocation system explosion was created due to the computer and innovative programming paired with it. We all know the application names: Facebook, Twitter, Instagram, Foursquare, Google Maps and so on.

    These applications work so well because they know where we are based upon geolocation. Where’s the nearest McDonald’s or Starbuck’s? Any number of apps will show you and help you find the quickest route to get there.

    Geolocation has also enhanced how people drive with apps like Waze and Google Maps using phone and car location data along traffic routes to gauge traffic speed, flow and congestion. Technology has improved almost everyone’s ability to travel, find places more efficiently and help bring people together at any location. Theoretically, possessing a GPS-enable device should eliminate ever being truly lost.

    Was George Orwell right? Is Skynet next?

    Technology, along with bringing good uses for applications and devices into our everyday lives, also brings possible issues as well.

    Privacy advocacy groups are not a new concept, but the exploding use of electronic devices with GPS and geolocation capability has brought new life to their arguments regarding intrusion into our private lives. People sharing every detail of their lives opens up opportunities for identity theft and robbery by allowing critical data to be shared with the internet and all who use it. But the geolocation issue became a big privacy target with the phenomenal success of a smartphone app in the summer of 2016.

    The humble beginnings of Pokémon started in Japan in the late 1980s with an arcade game created for the Nintendo Game Boy handheld console. The object of the game was to collect pocket monsters or Pokémon in various areas played within the game console. It became the second best-selling character-based game system ever, with more than 280 million copies sold on various platforms. Over the years, the game turned into a worldwide sensation featuring comic books, trading cards and even a popular television cartoon. It was this base knowledge of the characters and the concept of the game that led to the exploding sensation of Pokémon GO during the summer months of 2016.

    pokemongo
    Photo: Pokemon Go

    This was the first mainstream app that blended a popular game with geolocation capability and a real-world environment, all tied together in an exercise to “catch ’em all.” The latest smartphones with high-speed streaming data provided the perfect game console for this new achievement for gaming with geolocation being a critical yet key component. Part of the lure of the game was catching many of the Pokémon in public parks and recreational areas, as they were placed there by game designers to allow easy access for players to find and collect.

    Many of these public places were also historical, so local officials along with private citizens began complaining of large masses of players descending upon these sites and not being respectful of their surroundings. Stories of littering, vandalism, loitering and harassment were published nationwide, yet the game continued to draw players in by the thousands. While its popularity has waned toward the end of 2016, the concept of geolocation-based games left an indelible mark on the public and lawmakers who represent them as something they don’t want to see repeated.

    Enter big bad government

    Here in Illinois, lawmakers introduced proposed legislation in November 2016 to curb the use of various public and private locations from within geolocation-based video games on smartphones and handheld devices. Listed below are excerpts from the proposed bill language:

    Section 1. Short title. This Act may be cited as the Geolocation Information Protection Act.

    Section 3. Purpose. The purpose of this Act is to preserve the personal privacy of Illinois citizens when it comes to their highly sensitive geolocation information and to allow Illinois citizens to maintain control over the collection and disclosure of that information by private entities. This Act is also intended to provide real property owners, managers, and custodians with an easily accessible procedure for removal of ecologically sensitive sites or locations, historically significant sites or locations, sites or locations on private property, or sites or locations otherwise deemed as dangerous by the real property owner, manager, or custodian from location-based video games.

    “Ecologically sensitive site or location” means an area designated by federal, State, or local government for protection from development or damage due to the presence of endangered species or threatened species as defined in Section 2 of the Illinois Endangered Species Protection Act

    “Geolocation information” means information concerning the location of a device that is generated by or derived from, in whole or in part, the operation of that device and that could be used to determine or infer information regarding the location of a person. (Bold added for emphasis by author.)

    “Historically significant site or location” means a site or location that has been designated by federal, State, or local government for preservation as a landmark, or any other site or location that the federal, State, or local government may designate as historically significant.

    “Location-based application” means a software application that collects, uses, or stores geolocation information. (Bold added for emphasis by author.)

    Section 20. Collection, use, and disclosure of geolocation information from location-based applications.
    (a) A private entity may not collect, use, or disclose geolocation information from a location-based application on a person’s device unless the private entity first:
    (1) informs the person in writing that his or her geolocation information will be collected, used, and disclosed;
    (2) informs the person in writing of the specific purpose for which his or her geolocation information will be collected, used, and disclosed; and
    (3) receives the person’s informed, written consent (including through an electronic means using the Internet) in a form distinct and separate from any form setting forth other legal or financial obligations of the person before collecting, using, or disclosing his or her geolocation information.

    (For full details: http://ilga.gov/legislation/99/SB/PDF/09900SB2901ham003.pdf)

    illinois-surveyors
    Logo: Illinois Surveyors

    A voice for the surveyor was spoken loud and clear when the Illinois Professional Land Surveyors Association (IPLSA) contacted the bill’s sponsor regarding the content. We expressed our deep concerns with the limits this legislation would place on our profession, on our efforts to serve the public and eliminate the use of thousands of historical monuments throughout the state. The various state and national surveying associations and societies will continue to press our legislators for reasonable legislation that allows the public protection they request, yet will allow the professional surveyor to complete their jobs and serve that same public.

    The bottom line is that privacy issues will continue to be a concern for most while technology progresses forward. Our environment is on the cusp of autonomous automobiles, virtual assistants and robotic equipment completely replacing our workforce.

    Yes, we have gained many new exciting technological advancements with computers and programming, but also have given up a lot of information in the meantime to make it work for us. It is virtually impossible to have one without the other, so we will need to make a choice.

    I hope we choose to continue progressing forward, yet realize we still need to have a memory of the past. A surveyor’s craft is heavily woven around the past, so let’s work together to make sure the critical stitching stays in place.

  • Data collection of WGS 84 information — or is it?

    Location, location, location. It’s not just the tagline for real estate and sales; it’s about all of us, all of the time.

    Thanks to technology, everything revolves around location these days. It is in our cars, smartphones, exercise trackers, and even our packages. GPS has revolutionized so many things in our lives, but most people do not know how it truly works. They get the general idea of satellites beaming radio signals to Earth and translated into a position on the Earth, but that’s as far as it gets for most.

    Understanding the location relationship by points on the face of the Earth is something much more involved and gets quite complicated. Thanks to sophisticated computers and programming power, this complex bundle of formulas and computations are solved behind the scenes with little effort. All we know is that when our location shows up on our phone, we can share it with friends and family, search for the closest coffee shop, or have it tell us how long until we get home.

    This also affects professional surveyors more than many of them truly understand. The introduction of GPS has allowed many to produce work products with greater efficiency, but without understanding the true geodesy, math and positional accuracies behind the technology.

    Let’s take a look back in time to understand where we have come, to better understand why knowing the basis of datums is so important:

    IN THE BEGINNING

    Until the early 1900s, surveyors only measured what they could see and didn’t allow for any curvature of the Earth, (it is round, by the way…). Only after the introduction of long-baseline survey projects was there any consideration for adjustment to survey measurements.

    Extensive surveying observations were performed nationwide to establish a network of standardized horizontal positions throughout the land. Using least-square adjustment methods originally developed by Carl Friedrich Gauss to help with estimation of orbital movement of the planets, this network was developed using the Clarke Ellipsoid of 1866 with a base point of Meade’s Ranch, Kansas.

    The observed location of the initial point was determined at 39°13’26.686” North latitude, 98°32’30.506” West longitude; from here, all latitudes and longitudes are measured using the Clarke Ellipsoid for reference.

    This datum, called the North American Datum of 1927 (NAD27), was used extensively by government surveyors and geodesists for many decades, but because of the highly involved mathematics involved in the computations, very few private surveyors were trained to work within the datum.

    More than 26,000 survey stations were used in the computation of NAD27, all being manually observed and measured. The electronic distance meter and long-range theodolite help proliferate more reference points over time, but still required heavy-duty computation to determine results for the new positions.

    THE COMPUTER AGE

    The implementation of computers, both mainframe and personal computers, allowed for further development of programming that analyzed survey data faster and more accurately than humanly possible. This technology allowed geodesists to compute positions with more reliable results, but still lacked significant involvement by professional surveyors.

    As I’ve covered in previous articles, the development of a global positioning system by the Department of Defense created the ability to establish locations nearly anywhere. Their work started in the late 1950s with the development of an inter-continental geodetic system (World Geodetic System 1960 or WGS 60) to work with other nations. Continued refinement in the WGS data allowed for the development of a new geodetic datum that would be Earth-centered rather than the fixed-station method used by NAD27.

    In addition to the measuring method, there was also a much larger number of monuments now available for implementing into the new system. Approximately 250,000 points were included in the initial database for the new datum along with additional terrestrial and Doppler satellite data to create the North American Datum of 1983 (NAD83). Improvements with NAD83 over NAD27 included the correction and improvement of data distortion from earlier observations through the increased densification of information.

    A big difference from the previous datum was the use of the Geodetic Reference System of 1980 (GRS80) instead of the previously implemented Clarke Ellipsoid. It also offered global projection rather than localized realization of data. Because of these large differences based on projection methods, use of a larger ellipsoid and basis of coordinate values, it is somewhat easy to distinguish the difference between the two datums. But like life itself, everything is subject to change.

    BUT CHANGE IS INEVITABLE

    nga-logoThe National Geospatial-Intelligence Agency (NGA) published a Standardization Document in July 2014 outlining WGS 84, its parameters and history, along with the intended relationship with local geodetic systems.

    The standards covered in the document included:

    • Coordinate Systems
    • The use of GPS in the development of the WGS84 Reference Frame
    • Ellipsoid and its defining parameters
    • Ellipsoidal Gravity formula
    • Earth Gravitational Model 2008 (EGM2008)
    • EGM2008 Geoid Model
    • The World Magnetic Model (WMM)
    • WGS 84 relationships with other Geodetic Systems
    • Accuracy of WGS 84 and its models
    • Implementation Guidelines

    NGA continues to improve and refine the WGS 84 reference frame in order to standardize all future GNSS measurement. Let’s take a look at a few more specific characteristics of our current reference frames.

    WGS 84 BASICS

    The WGS 84 Coordinate System is a Conventional Terrestrial Reference System (CTRS). It has a right-handed, Earth-fixed orthogonal coordinate format. The system origin also serves as the geometric center of the WGS 84 ellipsoid, and the Z-axis serves as the rotational axis of this ellipsoid of revolution.

    It was established in 1987 with the intent of aligning with the Bureau International de l’Heure (BIH) Terrestrial System, also known as the BTS reference frame. Initial accuracies of the reference frame were 1-2 meters; ongoing refinement was important to the NGA team and development continued.

    The WGS 84 Reference Frame has been updated six times, with revisions taking place in 1994, 1997, 2002, 2012 and 2013. These updates are intended to incorporate international conventions and to align with the International Terrestrial Reference Frame 2008 (ITRF2008).

    Environmental changes in updated models and methods have begun to make discrepancies in the relationship between the reference frames, so improvements have been made to cause these periodic changes to the WGS 84 frame. The intent and result of each revision has been to improve its accuracy and precision, so applying constraints to WGS 84 in order to align it with ITRF results in maintaining continuity with other GNSS worldwide.

    With this latest revision to the WGS 84 reference frame, WGS 84 (G1762), the transformation differences with the International GNSS Service (IGb08) is essentially zero. This means users of the latest version of WGS 84 can use the data in its original state to translate to international measurements when necessary.

    ITRF2008 was recently updated to ITRF2014, but maintains its consistent relationship with WGS 84 (G1762) with centimeter-level accuracy.

    The original WGS 84 reference frame is still used by most consumer-grade GPS devices (smartphones, vehicle navigation, etc.). It has retained the original major-axis value to eliminate the need for various updates and modifications for these devices and mapping software. This allows existing collections of geospatial data to retain its values and not be subject to transformation or additional computation.

    NAD83 BASICS

    The NAD83 coordinate reference system is a horizontal adjustment of existing data from previous surveys, Doppler and Very Long Baseline Interferometry (VLBI) data. The geocentric datum is earth-centered/Earth-fixed, utilizes the GRS80 ellipsoid, and is intended to be identical to the original WGS 84 reference frame with the origin at the center of the mass of the Earth.

    The implementation of GPS-based data collection uncovered a discrepancy with the originally calculated center of the reference frame of up to 2 meters. This revelation rendered the reference frame flawed under its original configuration with positional errors up to 1-2 meters being commonplace.

    By 1997, additional observation data was introduced along with application of high-accuracy reference network (HARN) information to greatly increase horizontal accuracy. This was followed by the addition of continuously operating reference station (CORS) data through 2002, and then by the implementation of the National Spatial Reference System (NSRS) in 2007. The last major re-adjustment occurred in 2011 with more observation and CORS data.

    It is from this framework that the State Plane Coordinate (SPC) systems were developed for localized use. Transformation parameters were created to allow smaller coordinate values for easier use in all types for mapping and data collection. This is also where most surveyors were introduced to a simplified form of geodesy, but without the complicated formulas generally associated with its use.

    Hardware and software enhancements have made the implementation of SPC systems much easier than past computations. The continued refinement of the NAD83 system through significant adjustments and equipment upgrades has given the surveyor a lot of confidence in this system, but I still caution our profession to promote QA/QC programs to verify the information being collected. GPS data acquisition techniques are not infallible and appropriate caution during use is still required.

    SYSTEM COMPARISON

    The concept of a world geodetic system is to provide a globally dedicated reference system and to minimize or eliminate the need for local systems. The usual reason for a local coordinate system was to meet the needs for an area before the implementation of a larger system was possible. So often, the worst part of having and maintaining a horizontal system separate from a world system is the means and methods of transformation/translation of data.

    In the meantime, here are a few of the main differences between WGS 84 and NAD83:

    • While both use a similar ellipsoid, they differ slightly and thus create different results.
    • The coordinate system for WGS 84 is geographic, and the NAD83 system is projected.
    • WGS 84 values are points in space, while NAD83 coordinates are physical locations on the Earth.
    • WGS 84 is based upon the NAVSTAR satellite system, and the NAD83 system is based upon a network of ground points, observation data and CORS.
    • WGS 84 ellipsoid is defined as a geocentric, equipotential frame, whereas NAD83 considers GRAV-D data collection and tectonic plate velocities.
    • While the original WGS 84 system aligns with the NAD83 (1986) adjustment, further refinement of WGS 84 has been completed to maintain similarity to ITRF realizations.

     

    Until there is a redevelopment of the GPS system (including hardware), we must realize the limitation of each system and work together to make sure the relationship is understood by all who work with it.

    DATA COLLECTION NOTES

    With the advances in GNSS receivers, data collectors and RTK network opportunities, GPS data has proliferated greatly in the past 20+ years. What began as simple data collection with complex computing necessary to determine positional values has now turned into a plethora of available systems at your fingertips. Surveyors are now considered an “expert” in geodesy overnight, with very little education or knowledge of what they are truly measuring and publishing for coordinate and geodetic values.

     

    A majority of GPS data collection happens in a real-time network (RTN) scenario: (1) with a base station on a published coordinate point or OPUS-derived value, or (2) with a cellular-based RTN. Both situations are typically constrained by built-in NAD83 parameters within the data collector software to produce localized or state plane coordinate values. For projects that rely on these coordinates, these methods are perfectly acceptable.

    google-earthWhere the fork in the road appears is when geodetic values are required for data collection of geographic information system (GIS) database creation. Many GIS users understand the difference between WGS 84 and NAD83 data, whereas the typical professional surveyor does not. The data required for GIS use (such as Esri, Google Earth and Microsoft Virtual Earth) is typically defaulted to WGS 84 because most mapping is done for use by those with the simplest needs: the consumer. Consumers are using GPS in many personal devices, and keeping the programming and mapping requirements simple is key to their success. Excessive accuracy is not necessary when it comes to these devices, so a meter or two variations is perfectly acceptable. That is why the original WGS 84 reference frame is programmed into these devices and is still utilized for most large-scale mapping needs. But what happens when the mapping needs to be more precise?

    The need for precise data collection gets us back to the surveying community. Information collected by most surveyors is assumed to be in WGS 84 because “That’s what my data collector told me it was.” Ideally, the best way to gather actual WGS 84 values is to occupy the required locations and collect satellite data using a stationary, dual-frequency GPS receiver and noting the correct epoch and associated fixed-station GPS coordinate data used. Locations derived from data collected in local coordinate systems and transformed to WGS 84 values will be subject to characteristics and distortions potentially affecting the local system. This leads your subject data down an uncertainty path that may not be acceptable to your delivered product.

    Typically, data collected in NAD83 (2011) is in the 1- to 2-meter accuracy range from WGS 84 as previous discussed. These accuracies are not usually acceptable in the surveying world and hopefully not in most GIS base-layer situations either.

    One of the best solutions for high-accuracy data collection that will be more compatible with GIS database needs is to start your data collection with ITRF-based points, if possible. This method keeps your data consistent with current WGS 84 reference frame parameters and will fit seamlessly into most systems as required. Most hardware and software systems allow for its implementation as a coordinate system option and is just as easy to use as our normal NAD83 based systems. This helps provide less headache with data correlation to the client’s requirements and keeps the playing field closer to level.

    For surveyors, here’s the bottom line: our responsibility is to provide the client data in the most accurate and precise condition possible. Our profession needs to re-educate ourselves to better understand what the data collector is truly producing rather than relying on a wing and prayer that it meets the client’s needs.

    Think back to your early math class days; we spent many hours learning trigonometry functions by hand before we were turned loose with a calculator with sin, cos, and tan buttons. Learning longhand what was being produced helped us to understand how those complex calculations were completed.

    We need to think of this GPS data collection process in the same manner, and not just hope the “ghost in the machine” spits out the right numbers for the project. The worst thing you can tell a client is that you “think” the data is correct because you’re just not sure…

    BUT THERE IS GOOD NEWS…

    The good news for geographic data users in the United States is that the National Geodetic Survey (NGS) is working on a new datum that will incorporate radical new changes in combining horizontal and vertical datums. Visit the NGS website for more information. The initial framework sounds very robust and user-friendly, so keep your eyes and ears open for more details as they develop. I’m looking forward to the new system and so should surveyors everywhere.

    The problem sometimes with technology is that it moves forward so quickly  that good innovations get passed over due to previous acceptance and reluctance to upgrade (such as Sony Betamax, Microsoft Zune, etc.). This has been true with geodetic datums and the introduction of GPS for mainstream use. It will be an age-old issue, but I look forward to better and brighter days ahead.

    Now, where did I leave my trusty Junior Geodesist Secret Decoder Ring?

  • GNSS coordinates as survey evidence — friend or foe?

    GNSS coordinates as survey evidence — friend or foe?

    In my last column in July, I shared the situation with U.S. federal lands in Alaska being surveyed with GNSS and subdivided by coordinates, instead of subdivided by traditional methods of setting monuments.

    The topic drew a varied range of responses and opinions. While some felt the article was on point with setting bad precedents, others added that it was time for technology to take over and not put so much priority on physical monuments.

    I do believe there is room for everyone at the table and would like to use this article as a follow up to more conversation. Let’s start with a comparison of monuments versus theoretical/published positions for parcel corners and land ownership.

    On the technical side

    Space – the final frontier. Everything these days has a spatial address and/or relationship. Thanks to the U.S. Department of Defense (and taxpayer’s money), the global positioning system was created. While originally designed for military use, the civilian application has opened up a new world of spatial technology.

    From Google Earth and municipal GIS to vehicular navigation and Pokemon Go, spatial data has expanded and tracked almost everything in our lives. Where’s the package from Amazon Prime? Let me check the app on my phone and it will show me where my wife’s shipment of make-up is via RFID chips on the box. Where are my buddies tonight? The “Find Friends” app tells me in seconds. All things spatial and right at your fingertips.

    So that brings us to surveying and how technology has influenced its historical methods. Coordinates aren’t new; the introduction to State Plane Coordinate Systems was developed and publicized by the U.S. Coastal & Geodetic Survey almost 100 years ago.

    First-order horizontal monument, U.S. Coast and Geodetic Survey, 1931.
    First-order horizontal monument, U.S. Coast and Geodetic Survey, 1931.

    This allowed for the creation of large networks to begin the framework of today’s GIS but not without its flaws. Instruments used for these measurements were very accurate but human error always played into the final computation. Positions established by observing Polaris and/or sun shots were somewhat accurate but often were too complicated for everyday surveying projects. For decades, the only projects in which state plane coordinates were utilized took place during larger state and federally funded surveys. Because of these limitations, use of state plane coordinates and networks didn’t have many followers.

    Forward a few decades and the invent of the electronic distance meter (EDM). Now there was technology available (albeit expensive) to measure large distances but it brought its own issues. Up to this point, surveyors didn’t need to worry about the earth’s curvature and atmospheric corrections but the EDM changed that.

    With the Eisenhower interstate highway system, more federally funded surveys were performed and surveyors were embracing state plane coordinates more than ever. Primitive GIS systems were starting to form but state and federal cartographers were the stewards of this data. Another big step was needed and the late 1970s/early 1980s didn’t disappoint.

    As mentioned earlier, the Department of Defense began implementation of the GPS network by sending a new breed of timing satellites into orbit beginning in the late 1970s. When decisions were made to allow civilians to receive GPS signals for positional use, a new era opened up for surveying. But just like route surveys, EDM’s and control networks, only large projects could sustain the funds necessary to utilize early GPS receivers. Over time, GPS equipment, like computers and software, became more advanced, user friendly and cost effective. Cost of entry to GPS technology became more affordable to most surveyors and expanded the capability of the profession to embrace state plane coordinates. For the surveyor community, the thought of an entire profession working within one large coordinate system was almost nirvana. It could help solve many of our ambiguity issues in comparing similar survey data. With today’s options of GPS networks, this dream is much closer to reality.

    In one of my previous articles, I shared my belief that the GNSS RTK network has been the single greatest improvement to the profession of surveying. The hard work put in by the National Geodetic Survey team in establishing and maintaining the National Spatial Reference System (NSRS) provides a thorough network that is confidently used nationwide and beyond. Additional Continuous Positional Reference Stations (CORS) are being installed nationwide and providing more surveyors with the network capability to perpetuate state plane coordinate systems literally anywhere. I, for one, like the idea of being able to share data with some certainty that most of my fellow surveyors are on the same datum.

    While the autonomous car may be several years out, the surveying community now has the tools to put all surveys and property corners on the same coordinate datum. Or do we?

    Every man’s house is his castle

    As a surveyor, the measurement of land has been the primary focus of my career and the biggest part of it has been the search and recovery of monuments. Other than family, a person’s home and/or real estate is their most prized and valued possession. Knowing where the limits of their ownership is very important; this is where the surveyor comes in and provides that knowledge. Establishing boundary limits with monuments is a critical role the surveyor performs; how do they get there?

    Monuments mean different things to everybody. Ask the person on the street what they define as a monument and they will most likely name the Washington Monument, Mt. Rushmore or another historical statue or building. History has a way with things and places being “monumental”. Here is Webster’s definition:

    Full definition of monument

    1. (obsolete): a burial vault: see sepulchre
    2. : a written legal document or record: see treatise
    3. a (1): a lasting evidence, reminder, or example of someone or something notable or great (2): a distinguished person
      b: a memorial stone or a building erected in remembrance of a person or event
    4. (archaic): an identifying mark: evidence; also: portent, sign
    5. (obsolete): a carved statue: see effigy
    6. a boundary or position marker (as a stone)
    7. see: national monument
    8. a written tribute

    Depending on what part of the world you are in, monuments of different sizes, shapes and materials are used for marking boundaries. Surveyors working westward after 1800 were setting hedge posts, large stones with pointed tops and stone mounds. It wasn’t until the Industrial Revolution with mass production of steel mills were iron bars and pipes used for setting section and property corners. The invention of the metal detector further increased the use of ferrous materials for corners and monuments by increasing the ability to recover the points at a later date. Over time, additional materials were introduced; brass tablets, steel reinforced rods, and stainless steel masonry nails being the most common.

    Typical property corner: 5/8-inch steel rod with ID cap (Illinois).

    Typical property corner: 5/8-inch steel rod with ID cap (Illinois).

    No matter what the material, points are set at appropriate locations to physically mark the intended corner. It is also the duty of the surveyor to inform the property owner of the results of the survey in order for parties being affected by the placed points to know where their boundaries are located.

    Trouble in paradise

    Surveyors have been measuring for centuries using a plethora of instruments and methods; how could introducing GNSS coordinates to everyday projects create issues? It once again comes down to training, understanding of the equipment and technology and how to relate vintage survey data to newfangled data collection and measurement. Here are a few of the potential problem areas:

    1. Working in Ground or Grid Coordinates? What geoid model are you working with? You mean there’s a difference? It’s amazing to me the amount of surveyors that don’t know that there truly is a difference. If you are using GNSS/GPS and don’t know the difference, put the receiver down now and pull out your total station. Same goes for the geoid model; if you don’t know the difference between orthometric heights and ellipsoid heights, look it up and learn ASAP. Your data will thank you.
    2. Relating survey data based upon conventional plane geometry versus GNSS data based upon spherical geometry. Depending on the age of the survey data, it could have been collected by several different method, (chaining, EDM, triangulation,etc.) and will vary from GNSS data collection. Just because your data collector coordinates reads to ten decimal places doesn’t make it more accurate that old measurements. Get to know what is acceptable variations in measurements from old work and when real trouble is lurking, not just the occasional tenth or two.
    3. Varying correction signals from RTN network providers. While any network being used for GNSS RTK data collection worth its salt is being monitored for anomolies, things happen and signals can get compromised. Check your data, then check it again. Just because the data collector says the horizontal and vertical precisions are within tolerances, they can and will lie. Check periodically to make sure everything is in good working order. Watch your satellite counts and constellations as well for good geometry. Just like any other measuring technique, proper procedures must be followed.

    These are just the highlights of potential issues and not intended to be a comprehensive list.

    Can’t we all just get along?

    On one side of the fence is Old Joe Surveyor with his trusty metal detector, shovel, total station and sidekick for a prism holder. He’s the one finding irons and shooting fences, looking for signs of occupation because “that’s the way he was taught; follow in the footsteps of the original surveyor.” He doesn’t like technology and would prefer if those who have it would just stay away and leave him be. For him, 2 + 2 = 4, but it might need to be prorated down to 3.95 depending on the monuments.

    On the other side of the fence is Kyle the New Surveyor/Geomatics Professional. He’s talked his boss into the latest toys; GNSS on an RTN network, robotic total station with scanning capability, and working on the getting the UAV flying soon with his Part 107 certification. He sees the world as one big GIS database and everything is spatial. Utilities, property corners, and improvements have coordinates with physical addresses just waiting to be collected and stored in the “cloud”. Everything is mathematics, equations and algorithms; numbers don’t lie. For Kyle, 2 + 2 = 4 because the professor said so and completed the proof during lab time.

    While I know these two gentlemen are the extreme opposites of most surveyors, they epitimize a great deal of what is seen in every day business. When these two cross paths, there will always be differences until we can work out common ground for both. For instance, my last article included the “Rule of Construction” for analyzing survey data:

    Priority of Evidence Rules

    1. Possessory Evidence
    2. Seniority of Title
    3. Documentary Evidence

    a. Call for a survey

    b. Call for monuments

    i. Natural

    ii. Artificial

    iii. Record

    c. Distance (or Direction)

    d. Direction (or Distance)

    e. Area

    f. Coordinates

    Kyle loves his coordinates. See where coordinates fall? This is because case law has established the higher weight of survey information. Distances and bearing are above them simply based upon how things have been establish and marked for many generations. Of course, Joe sticks to the monuments. Notice on top of the list is “Possessory Evidence”; fancy words for monuments or other features depicting occupation and/or possession. These are tangible, real items that are observed, locations recorded and relied upon by both the land owner and the surveyor to define boundary lines.

    This goes back to the section above about a “man and his castle” and he wants to know where his kingdom lies. It may be iron rods, fences, shoreline, creek, etc., but he can see it and know what he owns. Because these landowners are the clients of the surveyor, we provide them what they want; tangible boundary limits physically defined.

    But monuments can be a divisive as well. Here is another reason I don’t want to see coordinates take a higher priority:

    monuments-divisive

    As a young surveyor, the term I was taught was “pin farm” and they grow like weeds. Most surveyors feel their corner will be superior to the others and therefore set another rod right beside the others. Jeff Lucas, surveyor and attorney from Alabama, wrote an entire book on “The Pincushion Effect” because of situations like this. When several different surveyors using different GNSS on the same theoretical coordinate system stake a corner based upon varying evidence, this is what we get.

    Also, GNSS might not be involved at all and is simply based upon conventional survey data collection. Or some mix of all of the above. Either way, I count five (5) iron pins and the fence corner; which one fits the data best? Better yet, which one is right?

    The big difference with these examples versus last article’s concern about surveying tens of thousands of acres in Alaska that no one will ever inhabit is simple; it is setting a bad precedent. The surveys in Alaska are to be performed by the BLM and follow their specific guidelines for original surveys, so they are unique in that respect.

    However, by not setting corners per their own standards and utilizing a coordinate-based plat for subdividing townships will send an unintended message to surveyors throughout the states. That message will be that setting corners for government lines will no longer be necessary and simply file a plat with coordinates at your local recorder’s office. If you don’t think it will happen, just check out the multitude of surveyors who use the BLM manual for recreating sections by original surveyor instructions instead of retracement methods. Bottom line is they simply don’t know better.

    As I’ve stated in past columns, I enjoy technology almost as much as I enjoy surveying and hope the innovations continue. I want to continue to push the limits of what we can do with the equipment, software and data but also not forget who we are working for. The clients are the ones who rely on our expertise to show them what they own and how they can work with their property. Spatial data is here to stay and look forward to utilizing it more in all aspects of surveying and engineering. However, existing laws and court cases are going to have to catch up to the technology before we can start placing higher priorities on coordinates and digital data. I do utilize it as much as the next surveyor but try to use it wisely. After all, just like any other professional, aren’t we “practicing” surveyors?

  • BLM’s new GNSS protocols may set undesirable precedent

    alaska-907724_640

    Alaska. “The Last Frontier” is a fitting slogan for this great land. The rugged terrain and harsh winters make an environment that only the bravest inhabitants can stand. Here, one of the latest surveying battles is being fought; not between land owners, but within the professional surveying community itself and pitting technology against historical tradition.

    In the beginning…

    The United States agreed to purchase Alaska from Russia in 1867 for $7.2 million dollars, or about two cents an acre. In 1959, Alaska, with a land mass larger than Texas, California and Montana combined, became the 49th state in the union.

    For the professional surveyor, more than 20 million acres of federal government land is scheduled to be measured and divided for conveyance to the state for eventual sale to private individuals.

    Surveying can be a challenging profession, and creating new townships in Alaska is no exception. In addition to the difficult environmental conditions, new procedural and technological advances are contesting historical means and methods of the creation of newly surveyed township tracts. The two main items are:

    • establishing coordinate values at corners instead of setting monuments.
    • GNSS and potential issues with atmospheric interference and lack of satellite coverage.

    We will discuss the challenges ahead for the future of surveying in Alaska and how it will affect parcel division. While it is too soon to know whether or not this will bottleneck sales of parcels to new landowners, it does bring many technical and procedural questions for surveyors to the forefront.

    Challenging historical methods

    From the early days of our new nation, surveyors from the Bureau of Land Management (BLM) followed long standing procedures and placed retraceable monuments at various intervals along township boundaries for tract establishment, with two mile intervals being the predominant length for parcels in Alaska. The position of these monuments are held by subsequent surveyors to retrace these tracts for the state or individual owners.

    During the course of the original field surveys, crews tasked with establishment of the new corners will note natural and artificial features for reference to these new parcel lines. These features may be trees or forestry lines, streams and rivers, mountains or glaciers. Because of these environmental challenges, these surveys take a great deal of time and effort to traverse through the difficult Alaskan wilderness.

    However, the physical act of performing the survey is the only way to establish accurate ties to features found along the way. Surveyors will establish permanent markers at the chosen intervals along the township lines with measurements to nearby features for future retracement. Once placed, the monument becomes a corner for the township parcel and its position holds over any distance or angular measurement to other monuments or reference ties.

    Performing these surveys is very costly and takes a great deal of time, so finding ways to reduce the budgetary expenditure for this task has been a priority for the BLM. Modern equipment and technology has improved efficiency and cut down on some necessary manpower, but it still takes a significant number of people to traverse through the dense areas of Alaska.

    The BLM has proposed the following changes to establishment of township and section corners during property establishment through a system referred to as a “Direct Point Positioning Survey” (DPPS):

    Implementation Direction: When preparing official surveys for areas of land selected by the State of Alaska pursuant to the Alaska Statehood Act, exterior boundaries of the selection area will be shown on the official plat by combinations of dependent resurvey, incorporation of record surveys where closure is met, and original survey. For original surveys, all angle points along the exterior boundary of the selection area shall be marked on the ground with a physical monument and shown on the official plat by reported coordinate and reference relationship to the NSRS datum and existing control stations. When deemed appropriate and directed in the Survey Special Instructions, other corner positions along, or internal to, the exterior boundary of the selection area can be reported and fixed by measure using reported coordinate and reference relationship to the NSRS datum and existing control stations and other marked corners of the survey with reported coordinates on the official survey plat. For surveys conducted using DPPS methods, if a corner is not marked with a physical monument, the geographic coordinate reported on the official survey record as fixing the corner location shall be accepted as the only evidence of the original corner position. For corners marked with a physical monument, the geographic coordinates reported on the official survey record shall be accepted as collateral evidence of the original corner position; the actual monumented location will remain the best evidence of the original corner position.

    The BLM goes on to state the following conditions for implementation:

    • Ease of unofficial location of boundaries on the ground by using satellite positioning in mobile devices for groups like miners, oil and gas lessees, recreational users, prospective land owners, etc.
    • More economical future legal surveys when the need arises to mark the corners of property boundaries
    • A clear plan for future surveys that will allow efficient procedures for private land surveyors.
    • Reduced boundary uncertainty and costs due to monument destruction or disturbance.
    • Compatible and accurate boundary framework for GIS and other geospatial databases.
    • DPPS methods generate a greater certainty of comer positions and they are correct, consistent and repeatable.
    • DPPS methods introduce an economy of resources in the future for leaseholders and landowners when additional parcel boundary demarcation is required because geographic coordinates referenced to a known national datum are directly reported on the survey record and do not need to be calculated from the legacy measurement of bearings and distances.
    • Adoption of DPPS methods avoids spending substantial funds on unnecessary procedures like recovery, maintenance and rehabilitation of physical monuments in future survey work.
    • Surveys conducted using DPPS methods can be completed much more quickly than surveys completed using historical methods, thereby facilitating quicker patent to the State.

    These new policies are reshaping not only how traditional surveyors perform their craft, but also flies in the face of more than 200 years of boundary establishment and case law determination of property rights. Surveyors follow a strict guide when evaluating evidence in legal descriptions and/or property boundaries:

    Priority of Evidence Rules:

    1. Possessory Evidence
    2. Seniority of Title
    3. Documentary Evidence
      a. Call for a survey
      b. Call for monuments
      i. Natural
      ii. Artificial
      iii. Record
      c. Distance (or Direction)
      d. Direction (or Distance)
      e. Area
      f. Coordinates

    Coordinates have historically always been the last resort for corner positioning and/or retracement use, yet the BLM feels that GNSS measurements have increased in reliability to a place where they can be more heavily relied upon for establishment of section corners and other significant points. This is where the second issue comes to light: positional accuracies using satellite-based measuring devices at high latitudes.

    GNSS measurement and environmental challenges

    For most of us “regular” surveyors in lower latitudes, our GPS/GLONASS measuring equipment operates with little to no trouble. Newer receivers are taking advantage of not only the U.S. and Russian satellites, but will eventually use the European Union Galileo satellites, China’s BeiDou, the Japanese QZSS and India’s IRNSS. Once these additional systems are operational, achievable accuracies worldwide will increase dramatically but we are still several years off.

    The issues GNSS users in higher latitudes face are not only lack of satellite coverage, but several factors of environmental interference within the atmosphere. The result of these conditions and hazards are scintillation, positioning errors and cycle slips. These are very difficult to predict, thus increasing data-collection time and efforts to catch potential errors.

    Scintillation occurs when rapid changes in amplitude and phase are observed and directly impacts the signal from the GNSS. Solar radio storms (caused by coronal mass ejection), large- and small-scale ionospheric structures (causing unpredictable values in environmental electrons) and geomagnetic activity (aurora) are also factors that affect signal, create cycle slips, and thus deteriorate the positional accuracy.

    Studies performed by several technical teams (including NOAA/NGS) have shown that variations in position occurs often at CORS stations with little or no warning. Ongoing studies are helping to establish potential patterns in the atmospheric intruders, but will require much more analysis.

    Some of these issues will be solved with more satellite coverage from the pending systems, but it will also require additional monitoring equipment to help forecast when potential environmental factors are about to occur. These systems will take time and money to develop, and thus increase the budgetary requirement for a new surveying procedure that was planned to save time and money.

    But what does this all mean? From the historical side, placing monuments only at perimeter corners and not at township and section corners will place an extraordinary burden on future surveyors to “follow in the footsteps” of the original surveyor.

    This flies directly against the duty of the retracement surveyor, so that alone will be a challenge. Studies have shown the instability of GNSS-derived accuracies as performed by highly trained scientists who are well educated at atmospheric recognition. Pairing a revised retracement procedure with providing GNSS-derived coordinate values with potentially faulty data instead of placing monuments is a recipe for disaster.

    The biggest issue for most surveyors with implementation of the DPPS method will be for other jurisdictions to follow suit. The main priority of the surveyor is to protect the public. Making a change to allow coordinates to become acceptable evidence will lead to many more boundary disputes and court cases. Too often I hear that one surveyor thinks his coordinates are better than the next (myself included), yet we are dependent on what the receiver gets and the software calculates.

    The surveyor tends to believe that GPS is “our” measuring device, and we have exclusive knowledge of its use and application, but we would be hard pressed to tell the client exactly what the equipment does to determine position and distance. A general understanding of your measuring tools is necessary, but it still comes back to knowledge of boundary law and the principles of how to apply them.

    While I applaud the BLM for proposing a new procedure to help reduce costs for new original surveys in Alaska, I’m also afraid of the residual effect everywhere else as it establishes a new precedent.

    So in the meantime, let the surveyors keep setting monuments and we will revisit the coordinate standard another day. And to quote the surveyor’s favorite geodesist, David Doyle: “Good coordination begins with good coordinates.” So let’s make sure we have accurate data.

  • GNSS and the real-time network: The surveyor’s best friend

    A lot of talk is being made about UAVs these days and how this technology is going to revolutionize many industries, with surveying being one of the biggest users.

    I won’t deny the impact this new tool is going to have on our profession (as written in my last column). But I don’t think it will compare to the use of GNSS technology and how it modernized measuring methods for the surveyor.

    Gammon-reelI’m often asked by young surveyors what I think is the biggest improvement experienced by the surveying profession. Ironically, I asked that same question to my teachers when I was a new survey technician. My mentors will talk of the electronic distance meter, the theodolite or the total station. (Some old timers even told me the best improvement was the gammon reel for their plumb bob or the reel for a steel “chain”!)

    While these were good advancements, for me the biggest improvement was the introduction of GPS into surveying, followed by the advancement to real-time network capability. Now, coupled with modern communication methods of radio or cellular transmission to permanent base stations, the GNSS rover has become one of the most valuable tools in the surveyor’s toolbox.

    To understand the importance of GNSS technology and its use by the surveying community, first take a look at the history of the profession and method/devices used for measuring. Land surveyors have been measuring boundaries of parcels for centuries, dating back to Egyptian times and workers known as “rope stretchers.” Their use of rope with knots tied at specific intervals was the measuring stick of the time period.

    As centuries passed and measuring units were developed, surveyors used these dimensional tools for measuring and describing land parcels. By the time the early settlers of America began traveling westward, surveyors were using a 66-foot-long Gunter’s chain made with 100 links, each almost eight inches long. Over time the links would stretch until the surveyor’s measurements were not accurate for land surveys.

    By the early 1900s, tapes made from low-expansion steel became more widely used and much more accurate for surveying. The early 1960s brought new technology with measurement systems using laser light beams with the ability to travel several miles with sufficient accuracy.

    A total station.
    A total station.

    The electronic distance meter (EDM) allowed the surveyor to cover longer distances in much less time than the conventional method of the steel tape, leading to more productive field time. This technology was further refined to be installed inside of traditional theodolites to create the modern total station instrument — still used today for basic measuring of angles and distance. Almost all surveying projects can be completed using a total station, but the invention of a remotely available measuring device would be a welcome tool in the surveyor’s toolbox.

    Enter the 1980s and the adaptation of the military’s satellite measuring system for civilian use. While early users and developers needed a Ph.D. in mathematics to configure its use, GPS measurement revolutionized long-distance measurement for the surveying profession. Static GPS measurement took many hours of data collection and even longer processing time, but with terrific results and with tremendous accuracy.

    Further refinements with hardware and software configurations brought more affordable and user-friendly systems that gave surveying community another resource for accurate measurement. While the use of real-time kinematicc (RTK) expanded greatly in the late 1990s and 2000s, the big difference in the past 10+ years has been the introduction of real-time networks and permanent base stations. This advancement helps by eliminating the need for a base receiver and radio with an amplified repeater, and thus another employee guarding the idle base station equipment.

    Depending on the surveyor’s location, real-time networks are readily available by paid subscription or through publicly funded transportation department. These systems are very reliable and don’t require a six-figure investment in equipment.

    All survey data-collection methods, no matter the measuring procedure used and positional accuracy required for the project, needs to follow a strict quality-control procedure for verification of its content and position. The old adage “Measure twice, cut once” works well here, too, so let’s discuss what is involved with good measuring procedures.

    Measuring procedures

    Prior to any field measurements are taken, it is good practice to verify satellite availability during your planned measuring period. The U.S. GPS currently consists of 31 active and healthy units orbiting the planet and crisscrossing the sky 24/7. The geometry created by radio signals received from these satellites constantly vary in size and strength. By using mission-planning software, the user can accurately predict the best times of the day to collect positional locations with the highest accuracy and repeatability. Low numbers of satellites or strength of constellational geometry can lead to inaccurate locations and incorrect measurements between points.

    The introduction and allowance of other satellite systems into our data collection system (GLONASS, Galileo, BeiDou, IRNSS) will enhance the availability and strength of constellation geometry throughout the data-collection process.

    Another potential problem for GNSS data collection is solar storms, sunspots and other radio interruptions. Most manufacturers will notify the user of major atmospheric radiation events, but check the NOAA Space Weather Prediction Center (SWPC) website for updates on potential events. The key here is to plan your field collection prior to execution, in order to reduce errors in measurement or even interruptions to completing the work in a timely manner.

    Survey results are only as good as the measurements, and following strict guidelines is very important. When using survey-grade GNSS equipment in a real-time function, many items need to be monitored while collecting data to ensure good quality positions. Here are items as listed by the National Geodetic Survey (NGS) in the “User Guidelines for Single Base Real-Time GNSS Positioning” manual on the NGS website:

    • Accuracy versus precision
      • Accuracy is how your collected data compares to the defined standard.
      • Precision is how often the solution is repeated.
      • Achieving both provides necessary confidence in field measurements.
    • Redundancy
      • The ability to collect similar measurements at different times, satellite constellation geometry and atmospheric conditions.
    • Multipath
      • Minimizing opportunities for measurement to be affected by reflected or misdirected signals.
    • Position dilution of precision (PDOP)
      • Higher readings usually achieved when measuring during periods of weak satellite constellation geometry.
    • Root-mean-square (RMS)
      • Statistical measurement of precision notifying the user of the positional quality of the measurement based upon quality of satellite signals.
    • Site localizations/calibrations
      • Basing the strength of survey network on the location of the base station and the accuracy of the monument it is located upon.
      • Typically used when real-time network connectivity is not achievable.
    • Latency
      • The delay of the received satellite signal data and correction information at the base, sent to the rover for computing correction values.
    • Signal-to-noise ratio (S/N)
      • Ratio in which burdening noise is measured versus the actual signal from the satellite.
    • Float and fixed solutions
      • Floating solutions occur when precision for survey-grade measurements is not met due to noise, lack of satellites, weak satellite geometry and latency.
    • Elevation mask
      • This setting is a filter to eliminate signals from satellites below the user-defined angle, thus eliminating opportunities for weak constellation geometry and noise interference.
    • Geoid model
      • Correction model used to improve vertical measurement with GNSS data collection by incorporating previously determined elevations across a wide area.

    While all of these components are necessary for quality data collection, one of the most critical steps is horizontal and vertical verification on published or previously established control points or monuments. By checking into a known point before every data-collection session, you can eliminate errors in rod/antenna height and/or coordinate system setup. Checking a known point can also help determine if the correction signal is providing accurate information, either from the RTK base station or as part of a subscription service via cellphone or radio. It will also help discover poor PDOP or RMS due to weak satellite configurations. Also, if the rover unit takes longer than usual to initialize, a potential data-collection issue may occur to bad conditions.

    The biggest complaint I get (and see) is field crews not checking the accuracy of the GNSS unit during the course of a survey. Hopping out of the vehicle, firing up the data collector, and taking a measurement multiple times without redundant measurements or verifying existing control points/monuments is a recipe for disaster.

    Here are my keys to successful data collection with GNSS technology:

    1. Keep the equipment is good working order: batteries charged, receivers and collectors in travel cases when not in use, poles kept in safe places and regularly checked for plumb.
    2. Utilize a checklist for project startup.
      a. Horizontal coordinate system to be used.
      b. Vertical datum to be used.
      c. List of multiple published or previously established control points for datum verification.
    3. Once receiver has a fixed solution, verify horizontal and vertical position on known point.
    4. Minimize loss of fixed solution times, recheck when establishing new fixed positions.
    5. If possible, recheck main control points at various time throughout the day to establish redundancy.
    6. Reverify at the end of the session and at the end of the day.

    While GNSS has greatly decreased field time for covering large areas quickly, it must still be used correctly in order to provide accurate positional locations. The accuracy of these positions are what the measurements of the surveyor relies upon, and they must meet a high standard of confidence. Our profession prides itself on being called upon as the “expert measurer,” so our methods of measurement must be up to those standards.

    While it took a little time to get the cost-effectiveness, reliability and user friendliness to a level of affordability for the surveyor, GNSS has become one of the best tools in our toolboxes. GNSS has revolutionized modern surveying, and I, for one, appreciate its ability to help me offer my services as an expert measurer.

  • Unlicensed UAV services threaten survey profession

     

    Unless one has lived under a rock for the past few years, it is hard to miss the influx of unmanned aerial vehicles (UAV), otherwise known as drones. Once considered expensive toys for hobbyists, these vehicles have become the hottest ticket in town for gathering aerial photography and video with professionals and amateurs alike.

    Miniaturization of cameras, batteries and GPS receivers has allowed these former toys to become important tools for many different users. Like so many other pieces of equipment that have become more affordable to the general public, it still requires trained and licensed experts to produce data and deliverables from the UAV and applicable software. The trouble with all this rapid growth in technology is finding truly qualified users who understand that UAVs are just another tool to compete a task and not a replacement for the trained and licensed professional.

    Surveyors are facing this challenge every day as technology races ahead. The market for UAVs in the surveying environment seems to have blossomed along with the worldwide boom. Services utilizing UAVs by the unlicensed and non-professional vendor is becoming the largest threat to the surveying profession. Firms advertising “eliminate expensive survey crews” are becoming more visible in print publications and on the Internet as cheaper alternatives to the licensed professional surveyor.

    To fully understand the hazard these individuals and firms are presenting to the public, we shall first look at the laws that govern the surveying profession. For example, from my home state is an excerpt of Illinois Professional Land Surveyor Act of 1989 (225 ILCS 330/) referring to measurements to be performed by the professional land surveyor (see excerpt at the end of this column.)

    This act defines the tasks that are to be undertaken by the licensed surveyor. Like most professions, the surveyor is required to obtain a bachelor’s degree with a specific number of surveying classes along with four years of responsible charge of surveying duties. Illinois State Statutes also declare that those who offer these services without the proper licensing or training can be charged with Class A misdemeanor for a first offense, and guilty of a Class 4 felony for a second or subsequent offenses.

    Part of being a professional surveyor is also utilizing the proper tools of the trade. For the past 20 years, GPS has become the single greatest asset to the surveyor. It has allowed many tasks to be completed in greatly reduced time with more accurate results. The surveyor now has several different GPS tools to choose from, depending on the task. In my last column, “Data is the crop — GNSS used by surveyors and farmers,” I wrote of the varying levels of GPS receivers used by land surveyors and mappers for different types of data collection. Here is a brief review:

    Mapping Grade GPS (>= 3 meters)
    This handheld unit is primarily used for mapping utilities and improvements that don’t require high accuracy.

    Differential GPS (<= 1 meter)
    These systems are used by hydrographic surveyors for use in mapping lake and river bottoms as well as surveyors working in open pit mines producing existing condition maps and volumetric surveys.

    Real time kinematic (RTK) (<= 2.5 centimeters)
    RTK systems range from base station/rover/radio combination to virtual reference systems (also known as “real time networks” or RTN) over cellular networks. These systems are prevalent with today’s surveyor as standard measuring equipment.

    While using any of these GPS types, surveyors have procedures for measuring and checking their results in a precise and particular manner. Most surveyors primarily use RTK or RTN-based systems for all of their work and require continuous data verification throughout the collection process. Control points and monuments are utilized for quality checks and verification in order to assure the work being performed meets the required accuracy standards.

    The integrity of the data is closely guarded by the surveyor as their duty to performing the job correctly and efficiently. These policies and procedures are also paramount to the work being performed remotely by a UAV under the direction of a surveyor, so the service being provided is professional.

    The consumer (and small business) side of the UAV industry, however, is much different. The costs vary from $100 and up, depending on rotors, batteries and camera capability. One of the main advances has been the implementation of GPS receivers but with much lower accurate positional information.

    Like the dashboard GPS screens in cars and now GPS on every smartphone, John Q. Public assumes that the geographic positions provided by the UAV receivers are very accurate and have little to no error. On the contrary, most GPS receivers in these units provide autonomous positions with horizontal accuracies in the 2-5 meter range (at best) and can follow a preset flight path created on a smartphone or tablet.

    Also, these UAVs and software have also opened the door to new opportunities for entrepreneurs everywhere. The high-definition cameras with capabilities including 4K video and 15-20 megapixel images allows the tech-savvy user to fly and collect aerial photography and video that rivals companies with a fleet of aircraft and expensive cameras. These images are used with software that stitches multiple shots together based upon GPS location and common elements in each image to create 3D models for terrain analyzation. No “on the ground” data verification or survey measurements are utilized to confirm the image’s integrity or scale.

    Many vendors are also offering verification of quantities in gravel pits and mining operations utilizing the volume calculation modules within the software. These images may be a pretty picture but for surveying purposes, they don’t pass the sufficient accuracy tests.

    In contrast, survey-specific UAVs and software will cost $25,000 and up, but are designed to provide the necessary accuracy required to perform a professional surveying task. Flight planning with state plane coordinate systems are most common, as these systems directly relate to the surveys being performed in conjunction with the aerial flights. Panel points are set for identification within the images to verify known distances and accuracy checks.

    Volume quantities can also calculate with greater accuracy based upon these methods and procedures. Surveyors are also using the technology to perform ongoing as-built conditions in order to provide construction sites progress reports of installation of improvements. All of these tasks are possible with the higher accuracy capability of the survey-grade UAV under the direction and guidance of the professional surveyor.

    The surveyor, with the professional knowledge of geographical and state plane coordinates, also understands the boundaries of “no fly zones” and the use of geofencing by the U.S. government and the UAV manufacturers. As these zones become more prevalent, knowing how to honor and adapt to them is already a staple in the surveyor’s tool bag.

    The State of Illinois is currently drafting rules for UAV operation that will coincide with the proposed rules due from the FAA in June 2016. While most concern from the public is in regard to privacy and public safety, I am concerned as a professional surveyor that the current trend of use of UAVs by unlicensed professionals for surveying and engineering services will harm the public as much as the other issues combined. Engineering designs that are based upon data collected by unlicensed professionals should not be accepted by governing bodies in an effort to protect the public. Licensed surveyors, utilizing the proper tools (including survey grade GPS and UAVs), provide the accurate data for these designs.

    Technology has made the UAV an exciting toy for most and a new tool for some industries, including surveying. Like any tool, proper use and instruction is necessary for the safety of the operator and the public. The UAV does not make its owner a surveyor, just as buying a pipewrench doesn’t make its user a plumber.

    For more information on UAV use and procedures, go to Know Before You Fly.

    Excerpt of Illinois Professional Land Surveyor Act of 1989

    (225 ILCS 330/5) (from Ch. 111, par. 3255)
    (Section scheduled to be repealed on January 1, 2020)

    Sec. 5. Practice of land surveying defined. Any person who practices in Illinois as a professional land surveyor who renders, offers to render, or holds himself or herself out as able to render, or perform any service, the adequate performance of which involves the special knowledge of the art and application of the principles of the accurate and precise measurement of length, angle, elevation or volume, mathematics, the related physical and applied sciences, and the relevant requirements of law, all of which are acquired by education, training, experience, and examination. Any one or combination of the following practices constitutes the practice of land surveying:

    (a) Establishing or reestablishing, locating, defining, and making or monumenting land boundaries or title or real property lines and the platting of lands and subdivisions;

    (b) Establishing the area or volume of any portion of the earth’s surface, subsurface, or airspace with respect to boundary lines, determining the configuration or contours of any portion of the earth’s surface, subsurface, or airspace or the location of fixed objects thereon, except as performed by photogrammetric methods or except when the level of accuracy required is less than the level of accuracy required by the National Society of Professional Surveyors Model Standards and Practice;

    (c) Preparing descriptions for the determination of title or real property rights to any portion or volume of the earth’s surface, subsurface, or airspace involving the lengths and direction of boundary lines, areas, parts of platted parcels or the contours of the earth’s surface, subsurface, or airspace;

    (d) Labeling, designating, naming, or otherwise identifying legal lines or land title lines of the United States Rectangular System or any subdivision thereof on any plat, map, exhibit, photograph, photographic composite, or mosaic or photogrammetric map of any portion of the earth’s surface for the purpose of recording the same in the Office of Recorder in any county

  • Data is the crop: GNSS used by surveyors and farmers

    Data is the crop: GNSS used by surveyors and farmers

    As technology continues to march forward, and storage and data evaluation use grows, the surveyor and the farmer will begin to use each other’s skillsets to increase their own productivity. So how do we get there? First, we must establish how each side uses their prospective GPS tools.

    As a child, I spent several summer vacations at my relatives’ farms in central Illinois. My early impression of working on a farm was one of long hours and hard work. Work and chores completed by my family members was very physical with no set hours to look forward to. My uncles didn’t get to set the schedules for rain and sun and had no say in whether or not a piece of equipment would break down.

    What I encountered as a child taught me that there was no technology in farming; it was nothing but hard work. The thought of using something as high-tech as GPS would have made most old-time farmers laugh you right out of the coffee shop.

    My career as a land surveyor has had its share of hard work at times, but it has been the technology that has always fascinated me. When I began as a rodman, the electronic distance meter allowed surveyors to measure distances more than a mile instead of hand taping the entire way, and with much more accuracy. Along the way, I’ve watched computer technology grow, with total stations that incorporate cameras and video and GPS receivers that provide accurate locations instantaneously.

    That brings us to our modern-day crossroads. As surveyors, we are constantly trying to find ways to incorporate our skills into other occupations to increase productivity. We also see the modern farmer moving away from small family operations with only several hundred acres, morphing into farm management corporations with tens of thousands of acres as well as millions of dollars of equipment.

    Efficiency is what they are after, and they are spending significant amounts of money on technology to make it happen. My own curiosity and research has opened my eyes to how far the farming profession has grown, and in many ways surpassed the land surveyor with technology. But I think there is still common ground that needs to be explored, so let’s start at the root of each profession.

    The Farmer and the Surveyor

    As different as the two professions may seem, farming and surveying have one large common link: data. More specifically, the tools, methods and procedures they operate to acquire the data used in their everyday jobs and projects.

    The implementation of GPS equipment and the ability to collect location data has greatly improved the productivity of both professions, but for drastically different reasons. However, as technology continues to march forward, and storage and data evaluation use grows, the surveyor and the farmer will begin to use each other’s skillsets to increase their own usefulness.

    So, how do we get there? First, we must establish how each side uses their respective GPS tools.

    The Land Surveyor

    The land surveyor and his or her staff use GPS daily, with varying degrees of accuracy. Here are a few examples:

    Mapping-Grade GPS Device (>= 3 meters)

    This handheld unit is primarily used for mapping utilities and improvements that don’t require high accuracy. The data and attributes acquired by this unit will be inserted into geographic information system (GIS) databases for inventory, and maintenance logs for future review and upgrade needs. Surveyors use these units for mapping items that require additional attributes and information necessary to improve the overall usefulness of a GIS database.

    Differential GPS (<= 1 meter)

    Differential GPS provides live positional solutions for applications that require more accuracy than mapping-grade GPS, at a reasonable equipment and operational price. These systems are used by aeronautical companies for mapping assistance, logistics companies for asset tracking, and emergency operations for 911 systems. These systems are also used by hydrographic surveyors for use in mapping lake and river bottoms as well as surveyors working in open pit mines, producing existing condition maps and volumetric surveys.

    Survey-Grade GPS

    Surveyors began implementing GPS equipment into their measuring repertoire in the mid 1980s with the introduction of data collection by static methods. This technique allowed for long-distance measurements with good accuracy and precision, but it came at an incredibly expensive cost.

    By the mid 1990s, real-time kinematic (RTK) equipment was introduced, and gave the land surveyor a new gateway into long-distance measurement with shorter occupation time and less cost. Additional enhancements to RTK systems included on-the-fly initialization, increased data-collector capability, and cellular/long-distance radio networks.

    These improvements allowed increased data-collection productivity, including mobile collection on all-terrain and survey vehicles. A topographic survey of a 40-acre parcel that would take several days of walking now is completed in less than 6 hours on an ATV. Boundary retracements of large parcels that used to take weeks of traversing the perimeter can now be done in a few days.

    Many credit GPS technology and functionality for greatly improving land surveying production as well as increasing accuracy and precision of the work.

    The Farmer

    Photo credit: ViaMoi via Foter.com / CC BY-NC-ND
    Photo credit: ViaMoi via Foter.com / CC BY-NC-ND

    Farming has been passed down from generation to generation for hundreds of years. History tells us this has been a hard life for many of these families as manual labor was at the root of the occupation. Livestock and family members were used to pull the necessary implements for planting each year’s crop, with most harvesting being done by hand.

    The Industrial Revolution brought the tractor and planting and harvesting equipment. After World War II, equipment manufacturers retooled their factories to increase the size and capacity of tractors. Even with the reduced manual labor that a farm tractor allowed, it was still a physical burden on the farmer planting crops and driving the miles of rows necessary to plant fields.

    Also, many agricultural areas became more organized, with local farm bureaus and associations being formed to help the farmer. These organizations provided information on how to increase yields in their crops; this data became the basic form of a GIS database for soils and drainage mapping well before digital mapping. These databases provided the initiative for the farmer to analyze planting methods and rates; herbicide, pesticide and fertilizer applications; and to review crop yields for notable increases and deficiencies.

    In the 1980s, yield monitoring equipment became a new tool for the forward-thinking farmer to invest in, analyzing how well his crops were producing. The only negative was the inability to accurately map the location of the various yield rates that would occur in the harvest. The farmer was forced to spend more time reading the yield analyzations in smaller parts of his fields in order to identify where adjustments were needed for increasing the output. Many farmers didn’t see the return on investment for this system, and those who did purchase such a system soon gave up.

    In the early 1990s, Rockwell International debuted the Vision System, a GPS unit using a U.S. Coast Guard correction system paired with a yield monitoring unit to map the location of yield rates during field operations. Trimble, John Deere and others were soon developing their own systems. All of these systems were expensive, delicate and too complex for most farmers to justify installing in their tractors.

    However, new discoveries in GPS technology during the late 1990s brought sweeping changes to this new tool for the farmer. While the term “precision agriculture” had floated around for a while, it wasn’t until the introduction of high-accuracy GPS that the statement reflected correctly on the industry.

    Differential GPS (<= 1 meter)

    John Deere began its pursuit of GPS technology in the early 1990s along with many others, but the company’s decision to continue pursuing this competitive edge is what led to several advancements for the farming industry. Deere’s work with Stanford University and NASA led to the revision of differential corrections for GPS locations to gain additional accuracy for a guidance system for Deere equipment.

    By 1998, John Deere presented a differential GPS system that provided 1-2 meter accuracy to assist farmers with smaller tolerances of precision field planting and harvesting. Innovations such as this led to many more advancements in the farming industry.

    Real-Time Kinematic (<= 2.5 centimeters)

    Today’s precision farming is more accurate than ever, with RTK networks providing a bulk of the coverage necessary to supply the farmer with corrections. In places where a local correction provider is not available, the farmer has choices of setting up his own base for correction or subscribing to other real-time networks via cellphone coverage. These systems allow for highly accurate mapping and guidance systems so the farmer has more control and information on his field and crops than ever before. Farmers now using GPS control in precise methods have more tools for increasing yields and production, including crop planning, soil sampling, pesticide/herbicide/fertilizer application and harvest analyzation.

    Crop planning used to be strictly in the hands of the farmer who drove his tractor in his field in an effort to follow the lay of the land. Today’s farmer uses topographic maps, aerial photography and mapping software to create planting patterns that make farming more efficient. By maximizing the planting configuration, this is also an opportunity to minimize fuel consumption. Soil sampling and weed mapping are now staples of many farmers’ activities.

    The farmer uses these methods to reduce the number of contaminants within the crop. He can also analyze the field’s health in order to apply the appropriate amount of necessary chemicals. These procedures are now computer controlled to vary the rate of application depending on the location within the field.

    Harvest analyzation has become the biggest source of data collected. Yield monitoring equipment was the first tool introduced into the electronic farming age. Now, coupled with GPS mapping of yield rates and volumes, farmers can accurately predict spot, regional and overall crop production from their fields. This data, along with soil mapping, is reviewed after the harvest and is used to determine a strategic plan for the next year’s planting.

    The biggest improvement, in most farmers’ opinions, is the implementation of steering-guidance systems. Initially produced to be strictly a guide to the driver, systems are now automated into the steering system to follow a predetermined path within a 1-inch tolerance. This frees the driver to monitor planting, spray application and harvesting operations.

    By turning the driving over to an automated system, field row overlap is reduced by up to 30 percent. This decreases double coverage of seed and spray application and it minimizes fuel consumption. This system also allows for less driver fatigue with the ability to work around the clock as needed or conditions dictate. Coupling this steering system with variable rate planters and sprayers, the farmer has a system that allows him to be more effective in managing and monitoring operations.

    Bringing the Two Occupations Together

    Both of these noble professions are using a highly accurate form of measurement and data recording, but we must review further how they can help each other. To do that, we must analyze what each is doing with the technology.

    Surveyors and GPS Use

    Roles of the surveyor are to measure land, provide his professional knowledge regarding parcel boundaries, and collect data for engineering and drainage purposes. A majority of this data is now collected by GPS methods and is in NAD83 state plane coordinates with NAVD88 elevations. This information can be supplemented by county and state GIS data as well. Surveyors also have knowledge of existing monuments by local, state and federal authorities tied to these coordinate systems/datums so all future surveys can be related to each other geographically.

    Farmers and GPS Use

    Farmers who have embraced GPS technology now have the power not only to map and collect data, but to also utilize previous data for crop efficiency. This ability to run a more efficient farming system is happening now for many farmers. The farmer is educated in regard to seed germination, weed and bug prevention, and maximizing crop yields so collecting this data has become a necessary task.

    The Farmer and the Surveyor — Harvesting Data

    The farmer and the surveyor can use their knowledge in many ways for the mutual benefit of increasing crop yields, efficiently working the land, and maximizing production.

    The surveyor’s knowledge of topography and drainage can assist the farmer with shaping of land to minimize water runoff and loss of key nutrients in the soil. This loss is estimated to be an average of two to three tons of soil per acre per year. Installation of drainage tile in addition to grading can be a critical part of minimizing soil loss, and the surveyor can help with this analysis.

    Accurate boundaries allow the farmer to know the limits of his property. The surveyor can provide this information so the farmer can maximize his planting configuration, yet not encroach on the adjacent property. The surveyor can also help with the creation of land-management systems to help farmland owners plan for financial decisions and tax strategies.

    The biggest opportunity for the surveyor is to offer assistance to the farmer who has little or no knowledge of data collection. This geospatial data can be confusing to those not familiar with this information. Farmers who become educated in analyzing and reading crop data can increase production and yields.

    Surveyors have the math skills and background to assist with the management of the data from a location standpoint. This effort will help the farmer know soil conditions, germination, spray application and harvesting to maximize the cost effectiveness of his investment in the land.

    Together, the farmer and the surveyor can create a successful partnership that can increase crop production worldwide. Data is the crop that brings them together, and planted with the right amount of care and nurturing, this data can become more valuable than ever.

  • Technology adoption slow in small towns

    Tim Burch
    Tim Burch

    I was born in a small town and I live in a small town. I’ll probably die in a small town, but only if you want to call a blue-collar city of 75,000 people small. My friends are small town and my parents still live here in this same small town. It was here in this small town that I started my career as a surveyor and circled back for an opportunity to be near family and friends.

    There are many towns, villages and cities in the Midwest that fit this description — mostly because of the agricultural background, but also because of the labor-intensive industries that provide most of the local jobs. Like those who prefer the large city hustle-bustle lifestyle, the small town attitude is the same, but in the opposite direction.

    My career as a surveyor has provided me with opportunities to work in both small and heavily populated areas. I have seen the definite distinction between the two environments, and have seen many of the technological advancements of the past few decades. Having worked in both the large urban multi-discipline engineering firm and the small town surveying firm, I see much disparity between how surveying is done today from varying firms. The biggest difference I see today is how surveyors are using GPS technology for their field operations.

    For the modern surveyor, GPS has become an everyday tool for measuring and data collection, but it wasn’t always that way. I began my career in the early 1980s working for a seven-person engineering firm in my small town, so GPS was never in our budget. Like most surveyors, I read about GPS use in technical publications, and was amazed what these magical boxes could do. The first generations of static receivers produced were very complicated and expensive. With long occupation times and even longer processing times, only the few companies who could afford the high-priced equipment and software were buying these units. Our small-town market could not justify this purchase, so we made do with conventional equipment as the norm.

    Today’s environment requires the working knowledge of handheld data collectors that are more powerful than the computer on the Apollo moon mission, laser scanners that collect millions of points per second, and GPS receivers that talk through cell phones to get sub-centimeter accuracy. Around the corner is wider use of lidar data collection as well as the unlimited use and application of UAVs with cameras and scanners, so there is no end in sight for technology and the surveyor.

    Most of the larger urban firms have established equipment and training budgets stay current with technology and not lose ground with the competition. Because of these strategic and spending plans, fee structures have increased over the years, and thus the cost of surveying has increased accordingly. This has also afforded those who stay up-to-date with current technology to push the limits of the equipment, and to continue to find new and useful ways to perform our work and provide newer services.

    By keeping their costs down, small-town and rural surveyors have kept their fees down as well, but to the detriment of the profession. In fact, the cost of a typical land survey in a small town has come nowhere close to inflation for the past 40 years in most places.

    In comparison, however, many industry partners of the surveyor have spent a great deal of money and time staying current with technology and production methods. Excavators and earth movers now have GPS-based computers controlling their movement and placement of material, as well as utilizing robotic instruments and GPS for layout of improvements and utilities. Architects and structural engineers are utilizing scanners for building and piping as-builts for existing and future improvements. Almost all farmers have tractors equipped with GPS-based control systems to help them plant and harvest with pinpoint accuracy, as well as apply herbicides or pesticides based upon high-tech mapping performed by crop analysts. Many land-management companies are gearing up with UAV technology to assist future operations with the information gathered by these flying wonders. Everyone around us is tech savvy, but the small surveyor seems to lag behind.

    I wanted to be exposed to new technology when I moved from a small town to a large urban city in 1998. The big improvement for the surveying community was the introduction of real-time kinematic (RTK) methods. The firm I worked for during the late 1990s and early 2000s had been using RTK systems since their introduction. Being able to collect points “on the fly” both manually and with ATVs greatly increased our productivity as well as accuracy.

    By the mid-2000s, almost every big-city firm utilized this technology as standard equipment for their crews. The only drawback to the RTK system was the need to leave a base-station receiver, so the introduction of the real-time network via cellphones in large market areas was another step in solidifying GPS use for everyday work.

    Another benefit of extensive GPS use in the large city area is that most of the firms keep their surveys on state plane coordinate systems, so exchange and verification of data is a much easier process. These larger urban firms also continue to upgrade to newer equipment as more satellite systems are introduced. The addition of GLONASS has increased our precision and coverage levels, with future systems including Galileo, IRNSS and BeiDou set to raise that bar even higher.

    On the contrary, many firms in small-town and rural areas have not progressed into new technologies because of cost and lack of cellular coverage needed for RTN systems. I moved back to my small town several years ago and have experienced this slip in technology firsthand. The big cellular carriers say they have 3G and 4G service in most places, but I can tell you from my travels that there are many places I have not been able to use our RTN receiver because of lack of cell signal. Most of the surveyors in our area still utilize an RTK system and will establish a position through OPUS or will assume a local coordinate system. Not many have upgraded their equipment to take advantage of GLONASS, so there are several steps they will need to take in the future to catch up to the industry. We also must travel greater lengths to recover NGS monuments for our positional verification, which will become more important as static monuments become a thing of the past.

    So with my apologies to Mr. Mellencamp, my job as a surveyor has not been just small town, and has provided me with many big-city opportunities. Our crews face challenges here every day that many take for granted while in the big city market, including RTN coverage, GLONASS constellation usage and many more NGS monuments for QA/QC. Having more of these items could greatly help our productivity, especially when stronger cellular coverage is expanded to more of our rural areas.

    I look forward to these improvements but will continue to work with our existing systems until that time. So look for us, surveying on in our small towns and locating all those little pink houses.

    This column introduces Tim Burch, GPS World’s new co-contributing editor for survey. Tim will alternate with Dave Zilkoski in contributing monthly columns to the Survey Scene e-newsletter. Tim is survey department manager for Chastain & Associates LLC in the Decatur, Ill., area. He has been working as a professional land surveyor since 1985, and is the secretary, Board of Directors, National Society of Professional Surveyors.

    For his next column in January, Tim plans to write about farmers and their technology in his area, focusing of course on GPS use. His article will compare surveyors’ processes with those used by farmers. (For Dave Zilkoski’s last column in October, see Establishing Orthometric Heights Using GNSS — Part 3.)

    Contact Tim via [email protected].