Tag: Public Land Survey System

  • The surveyor and the cadastre: Why can’t we be friends?

    The surveyor and the cadastre: Why can’t we be friends?

    Our ongoing battle with COVID-19 has shown we can adapt to radical changes. A big, but worthwhile, change would be to convert our existing land databases to a cadastre system.

    Any place that one may travel around the globe, they will find boundary lines that define properties and regions. For some countries, these parcels may be primarily owned by the government while in more developed nations, a large percent of the land is owned by private citizens.

    These parcels, when looked at together, together create a large jigsaw puzzle that seemingly fits together perfectly. Visually, all the lines should fit snugly to their adjacent neighbor so that the sum of the parts equals the whole. This system, called a cadastre, has many redeeming qualities and makes for an efficient choice of keeping an inventory of a region or country’s parcels and infrastructure.

    Origins of the cadastre system

    The cadastre system of parcel registration is the database of choice for determining land ownership and taxes on property through much of the developed world. Most of the places where this system of parcel registry consists of centralized governments usually have more oversight and legislative power than more “free” countries like the United States.

    Also, these countries in which these systems exist are typically small and/or have a manageable number of parcels so the development of the cadastre is much more controlled and maintained.

    To help us understand the origin of this parcel system, let us explore the background of cadastre and its beginnings:

    cadastre (English version: cadaster) (noun)

    Definition: an official register of the quantity, value, and ownership of real estate used in apportioning taxes
    Origin: Mid-19th century from French, from cadastre ‘register of property’, from Provençal cadastro, from Italian catastro (earlier catastico), from late Greek katastikhon ‘list, register’, from kata stikhon ‘line by line’.
    (Source: Merriam-Webster.com)

    In the years after the fall of the Roman Empire and through the end of many feudal societies, land ownership was transferred to individuals and families with the expectation of paying a tax to the government for this opportunity. Landowners could plant and harvest their own crops, raise farm animals for labor, and provide various goods and services to the community.

    Besides a small fee for conveyance, the government would ask for a “meager” tax to be paid regularly. Land that was sold to these individuals was recorded in a “cadastre” for tracking of ownership and tax payment. These records were primitive in nature and relied heavily on associating a parcel number to the owner versus an actual legal description to describe the property.

    It was not until more sophisticated and elaborate surveying instruments were developed that physical descriptions of the land were used to determine boundaries.

    Cadastre system gives way to legal descriptions

    This cadastre system of parcel management continues to exist in modern times in many parts of the world with one notable exception: The United States. Some will equate our parcel indexing system as being a traditional cadastre, but this numbering procedure is secondary to the means and methods of parcel conveyance in the U.S.

    For the non-surveyor reader, in the U.S. over the past few centuries a multitude of land systems have been used to establish parcel boundaries , each with their own unique system of describing land and conveyances. These types of land transactions began after the establishment of the colonial states and rapid expansion into previously unmapped territories.

    The push westward across the country introduced the Public Land Survey System (originated by Thomas Jefferson) and established sectional land divisions. As we encountered (and acquired) new territories, including the Louisiana Purchase and Texas, existing land measuring units and description methods were maintained to preserve these systems. No matter how the parcels are described, we rely heavily on the grantor/grantee system of transfer of ownership and rights throughout most of the country, with parcel numbering being applied post-transaction.

    So why is the grantor/grantee system the weak link in the chain of parcel establishment and conveyance? Many times, it comes down to the legal description and how it was created. Our system allows for the creation of a parcel by varying means by the professional land surveyor. The biggest issues occur when parcels are defined by a metes and bounds description with little to no reference to adjoining property or known monuments.

    When the legal descriptions of these parcels come into play, that is when the trouble starts, with calls made to attorneys and surveyors to help straighten everything out. To the common layperson who owns land or is looking to buy a parcel, it may seem unthinkable that parcels do not naturally fit seamlessly together with no gaps or overlaps. While the quality of survey data has increased in precision, the accuracy of marrying old data with the new suffers in many ways. How did we get to this point? Let us step back in the not-so-distant past to review how things have progressed throughout my short career.

    Set the flux capacitor to the early 1980s…

    Before computers and CAD, most agencies adopted a system of parcel and right-of-way mapping manually drafted on large sheets of durable paper or film. Depending on the municipality or county one was in, each sheet could represent either a quarter section (approximately 160 acres) or one half of a quarter section (approximately 80 acres) within a standard section of the Public Land Survey System (PLSS) established by the General Land Office (GLO) of the U.S. (now known as the Bureau of Land Management).

    These maps were based upon standard measurements within the given quarter section and drawn using 90-degree corners at the edges of the sheet. The linework depicting the parcels within blocks and larger areas was drawn as close to scale as possible but was intended to be a graphic representation of the shape rather than an accurate reproduction. Considering the technology and measuring devices/capabilities of the time, these records were very helpful in performing retracement surveys of existing properties.

    Because these surveys and parcel recordkeeping were performed long before computers, plotters, and CAD software became the norm, surveyors calculated and documented their work using manual computation and drafting from handwritten notes collected in the field. Not every parcel has 90-degree corners and lengths that are integers, so mapping departments for governmental agencies drafted new surveys and parcel boundaries to fit within the existing base sheets. Throw in the varying measurements from different surveyors and we have the real-life jigsaw puzzle that does not fit.

    Because the aforesaid mapping departments produced parcel numbering after the creation and conveyance of the property, the damage is already done in conforming with adjacent properties. This is an important factor in the professional surveyor’s responsibility to protect the public when performing an original survey for a new parcel and/or subdivision and utmost care must be observed.

    We have an army of land surveyors across the country shaping parcels to fit within a large jigsaw puzzle with an instruction sheet that must be strictly followed. One missed measurement or corner monument is in the wrong position, and we now have two or more parcels that will not fit together in the puzzle.

    Many mapping professionals will point, however, to the geographical information system (GIS) and how it improved this convoluted method of parcel databases. But did it?

    The digital spaghetti bowl

    For a large part of the U.S. where a data-intensive GIS has been created and maintained, it is a step in the right direction, but it still lacks the overall efficiency of a cadastre. Very few GIS databases contain survey-grade parcel establishment on recognized horizontal and vertical datums. Most are parcels and roadways digitized from old mapping and records that are vague graphical representations at best.

    One of the most important pieces of the GIS database are the base layers that contain control points and parcel/right-of-way lines that coincide with the datums that govern the region or state. Many governmental agencies do not employ a professional surveyor or surveying staff educated and trained to establish these datums within the database.

    Incorrect GIS parcels information. (Image: Tim Burch)
    Incorrect GIS parcels information. (Image: Tim Burch)

    Most times, the base layers are established “close enough” using aerial mapping and other data, including handheld GNSS receivers to collect infrastructure improvements. This is not a knock on these departments or individuals; they created the best possible database with the information on hand.

    When merged with aerial mapping and/or survey-grade data, the graphical information from the archival records can be confusing and misleading, especially to those who are not educated to understand the data.

    Is the cadastre an upgrade?

    The reason to consider converting all the existing parcel mapping and subsequent infrastructure/improvement mapping to a cadastre are simple: technology. We have previously discussed cities building digital twins (“Surveying and Geospatial Data,” GPS World, July 2020) utilizing remote sensing and a multitude of GNSS-capable products.

    Besides surveyors, many professions and trades use GNSS technology as a tool within their work environments. Our nation has experienced rapid growth in the last 150 years. The Industrial Revolution and the advancement of machinery, materials and building techniques have greatly impacted the ability to build more infrastructure and improvements. Many of these improvements and utilities have exceeded their useful life but have no timelines for replacement.

    Developing accurate maps of this aging infrastructure will ensure a proper data set from which a replacement design can be made. Couple this ability to work in a geospatial environment with other datasets, including aerial/satellite photography and lidar acquisition, and it gives us a nearly unlimited ability to map our world in appropriate datums with greater accuracy and precision. Governmental agencies could utilize this system to monitor illegal activities (such as dumping, mining, unpermitted construction) and gauge environmental concerns (drainage issues, problematic runoff, deteriorating infrastructure) to better protect the public. This system could also be used to refine our property tax system and work towards a more equitable means of assessing our properties.

    None of these potential changes and upgrades would have been possible 40-50 years ago; the invention and adaptation of GNSS have allowed these technologies to emerge. We continue to find new ways of measuring and mapping, so using these new techniques should be foremost on our minds to make these previous tedious tasks much easier to accomplish.

    The hurdles to change

    The biggest challenge, in my professional surveying opinion, will be adapting millions of parcels and deeds to a new database and applying them to the current datums. For instance, here is an example of potential (and recordable!) legal description:

    “Beginning at the northeast corner of the parcel, said corner being the intersection of the south right-of-way line of Smith Street with the east right-of-way line of Jones Street; thence easterly on the said south line of Smith Street to the northwest corner of the Williams parcel per Deed No. 12345; thence southerly on the west line of said Williams parcel to the north right-of-way line of Main Street; thence westerly on the said north line of Main Street to the intersection with the said east right-of-way line of Jones Street; thence north on the said east right-of-way line of Jones Street to the point of beginning.”

    Example of “bounds” legal description. (Image: Tim Burch)
    Example of “bounds” legal description. (Image: Tim Burch)

    While this is only a made-up example, it does represent a generally accepted legal description for parcel conveyance in most recording agencies. What does a mapping department do with this kind of legal description to place it accurately within a GIS or cadastre? Unless the four adjoining legal entities (Smith Street, Jones Street, Main Street, and the Williams parcel) exist geospatially within the database, the technician will have a tough time inserting this parcel into the records. Unless the entire surveying community is up to the challenge of working solely in an approved geospatial datum for all their work, much of this effort will not accomplish anything.

    The other roadblock to converting our current systems to a cadastre is the rest of the parties who work with legal documents, plats, and infrastructure; they may not be up to the challenge for making a radical change for the better. From the assessor’s, recorder’s, and mapping offices to the title companies and attorneys, many have an attitude that the system is too big to revamp. Because they only work in one part of the overall system, they do not see the benefit of blowing it all up to make it a more robust and useful database.

    Practically speaking…

    Revamping of any system within the varying levels of government is costly, no matter what branch or region is discussed. Governmental agencies are being asked every day to do more with less and provide more value in their services with few numbers of staff.

    While there may be a large upside to converting our existing databases to a cadastre, the downside is the effort and cost to do so. Yes, the new system would be scalable and easily adaptable for more infrastructure growth and could be expanded in an infinite number of ways. We can liken this proposed idea to converting all weights and measures to the Metric System: going metric will make lots of tasks and procedures easier, but flies in the face of everything we know as a society.

    However, our ongoing battle with COVID-19 has shown we can adapt to radical changes. The cadastre is a better system, but I do not want another worldwide disaster to convince us to change.

  • Surveying and geospatial data: the perfect couple

    Surveying and geospatial data: the perfect couple

    1800s theodolite. (Photo: ngs.noaa.gov)
    1800s theodolite. (Photo: ngs.noaa.gov)

    Everywhere we look, data is being collected, reviewed, analyzed and stored. It used to be that data was a static piece of information, like a piece of paper in a filing cabinet. Millions of pieces of data being created yet almost all of it never to be used again. The computer and electronic storage began a revolution of how we warehouse this information but that was only the beginning. Technology has turned data into a living, breathing beast few understand yet it controls most of our lives in various ways.

    Mapping of the earth has not always been about establishing boundaries and parcels; many of the early maps and plats were created to depict the topography of our world. While there are some indications that Middle East maps depicted parcels, the first examples of topographic maps were created during the Roman Empire era of 300 A.D. It is common knowledge that the Romans utilized primitive yet cunning engineering for roads, buildings, and waterways but it was the initial topography that was mapped that allowed them to design those forward-thinking infrastructure components. Because of the lack of sophistication in the measuring methods and data collection, these topographic maps covered small areas and often crude because of the materials available. Considering what they were working with, it is still incredible what they were able to map, design and build.

    Measuring devices and methods of data collection expanded over the centuries like most occupations and professions. By the 16th and 17th century, mathematics has been introduced at a wider scale through many educational facilities. Another profession, geographers, also advanced with the evolution of measuring devices and mapping techniques. It was during this period that we began to see a crossover with surveyors with geographers to create topographic maps with greater accuracy and precision through triangulation.

    In the 18th and 19th century, instruments became more sophisticated to assist in the determination of elevations and more accurate angle measurements. The concept of triangulation flourished during this period and significant mapping was made for most of the civilized world. The early 1800s saw the westward push of expansion in the United States and Thomas Jefferson, U.S. president and former surveyor, led the charge to map the existing states and divide the west into sectional land for sale to settlers.

    Besides the establishment of the Public Land Survey System, surveyors also provided topographic information for map of all sizes for future development planning. The late 1800s brought a large amount of topographic mapping information to paper through efforts by the U.S. Geological Society to map the entire United States. This information has been called the first land database; although crude in overall nature compared to today’s standards, it contained an enormous amount of topographic information.

    These surveys continued well into the early 20th century until a revolutionary invention coupled with a current technology merged: the use of a mounted camera taking aerial photographs from an airplane. Geographers and photogrammetrists were able to use surveying data to assist with scaling orthometric photographs to create aerial images of thousands of acres of land. These aerial photos became the base layer for determining topographic features and contouring, covering much more land than ever before. Additional innovations included advancements in stereo plotting and photogrammetric techniques to further create high sophisticated topographic maps for the era. This type of mapping was the gold standard for decades depicting existing condition and topographic features for most of the world until the early 1970s and the computerized data revolution.

    Computers take over the world (literally)

    1960s mainframe computer (Photo: NASA)
    1960s mainframe computer (Photo: NASA)

    While mainframe computers became more universally used in the 1960s, their use was contained to governmental agencies and large corporations. As the physical size of the computer reduced, the computing capacity increased, programming became easier to complete, and more applications were created to perform a variety of tasks. One of the biggest advancements for the era was electronic storage and analyzation of data through programming. Relational databases became a hot ticket for large datasets; geographic data was the perfect fit for this type of application. Modern mapping was on its way forward at warp speed.

    Topographic mapping was not lost in this shuffle. The survey itself is based upon data points located on the face of the earth so each point is just another chunk of information within the database. Programming continued to advance and soon methods previous completed by manual methods over long periods of time were completed in a fraction of previous efforts without fail.

    This effort was also joined with advancements in graphical technology to display this data on a computer video screen instead of lines of green text and numbers. Vector-based graphics, together with enormous point databases, helped create large topographical and geographical maps for many uses. During the same time the US put a man on the moon, mapping and platting of topographic information was also out of this world.

    The turn of the century brings big changes

    For the next decade, there were small advances in technology for topographic surveys and data points, but most were in presentation of data and increases in computing power. Pen plotters and smaller yet more powerful computers were becoming affordable to smaller companies, but it was still a large investment to get into the computerized data game for a surveyor. By the mid-1980s, electronic data collection with a total station was becoming the norm, but only meant collecting more points in a more efficient timeframe. The computing component did get faster but is still producing the same information of static data points.

    Ancient techniques and new technologies (Image: ngs.noaa.gov)
    Ancient techniques and new technologies (Image: ngs.noaa.gov)

    The mid-1980s also brought us a shiny new object: GPS technology. By the end of the 1990s, we were able to get out of our vehicle, start the receiver and collect geolocated points in minutes rather than hours. The big takeaway from this advancement is the geolocation component of the data point. Now everything can be related to one big dataset of topographical points. By creating a database with all our project data collected in the same georeferenced datums (horizontal & vertical), we can create digital models that replicate existing conditions.

    We can also add another big advancement in data collection: remote sensing technology. From laser and lidar scanners, photogrammetry, SLAM technology and ground penetrating radar, the innovations to collect data at locations we can “see” through sensing are now a reality. Another significant improvement with this technology is the amount of data points remote sensing can collect, both in timing and spacing. We are now talking small scanning projects that consist of billions of points within the site point cloud. We are fortunate that our computing power and storage capabilities has increased exponentially along with the remote sensing. (Remember doing a “regen” on your CAD file and having time to get a cup of coffee?)

    Lots of data — now what?

    Data is powerful, especially when it is harnessed in a robust system that can analyze and model for future use. Yes, this condition also applies to the surveying world, even though you may not be thinking about it now. We can use this data to create a virtual world that mimics the one we live in; the difference is that we exist in ours yet model and manipulate the digital version in our computer system. The technology is now available, and we can make a replica of our current world; however, why would we want to do that? There are lots of reasons to use technology and data to make sophisticated topographic maps (because that is what they are) for recording the world around us.

    One of the big differences now is that we have much more information about the data points we collect within our topographic maps. Sure, many surveyors will say that their data has not changed or evolved during their careers, but they would be wrong. Unless they are still manually writing it all down for hand plotting… (Hello! The 1960s called, and they want their field book back!) Every electronically collected point has attributes associated with the data.

    These attributes, while they may be simple, contain important information about the datapoint it represents. Horizontal location? Check. Vertical elevation? Check. Assigned point number? Probably. Field code? Most likely. But it also has one other important component: time. We now know exactly when that point was collected. Why is that important?

    Because, like a lot of instances, things change. Something collected today might not be there tomorrow. Time is just as important as the physical location and the type of point it represents.

    Gather these points together, throw them in one big model and you have yourself a graphical database that can be analyzed, reviewed, and used for planning and design. It may be hard to visualize with just simple survey data using GNSS and/or a total station, but couple it with a scanner or photogrammetry, you have a powerful hunk of data for which to work.

    Why is this workflow and modeling procedure important enough to dedicate an entire column about surveying and GNSS to? Because it used to be far in the future, but the need and availability to use it is now here in front of us. Surveying and GNSS are an important part of this effort to create three dimensional models. By using survey-grade data in conjunction with point clouds collected from remote sensing equipment, we can replicate the world around us in real time.

    Yes, Virginia, there is a name for the modeling process…

    At Intergeo 2019, Bentley Systems will be focusing on digital construction, digital cities, reality modeling and civil design. (Photo: iStock.com/alexsl)
    Photo: iStock.com/alexsl

    The name for the proposed modeling of this dataset is a digital twin. It represents a digital representation of a physical object or system. NASA famously used the concept for their space program to simulate situations and procedures of many different types of events. The concept has grown with the technology to graphically create almost anything through digitalization and computer modeling. Once the model is created, both actual and proposed data points can be included to represent the existing and future opportunities.

    The idea of a digital twin is not new; technology, however, has pumped more life into its existence by leaps and bounds with computing power and data storage capability. I remember, early in my career, going into an architect’s office and seeing the scale model mockup of a new development or building. The streets in the model were perfect, there were no drainage issues, and it was a neat as a pin. Fast forward to the construction of the development and field changes were at every turn. A digital twin will allow for better planning, more thorough design and creating more cost-effective development. Many large cities have started compiling data and building their digital twin, including New York, Singapore, Boston, and Rotterdam. Engineering and planning for new and replacement facilities is very expensive yet analysts predict that having a digital twin to work will save a significant amount of money and time.

    As a surveyor, what’s in it for me?

    Software capability for the surveyor is already here. Companies, such as Hexagon, Trimble, Topcon and Esri to name a few, have been developing their software to accommodate this concept for many years. Still, lots of surveyors do not know about it. And we should. Many of us live in places where the infrastructure is well past its useful life period and should have been replaced long ago. By starting now with survey-grade data to be put into a real-time model, we can help our governmental agencies and their consultants to move towards a digital twin that will ultimately save money and possibly lives.

    What this means for the surveyor is to further embrace technology and include remote sensing into your operation. If you have not started at least looking into UAVs and photogrammetry, you are already behind. Many aerial operations are making the next leap into mounting a LiDAR unit on their UAV to gain even more capability. Early adopters of laser scanners were probably second guessing their decision during the 2008 Depression but if they stayed with it, it will be a big payoff in the long run. The next leap will be into handheld scanning devices, including ones using SLAM (simultaneous localization and mapping) technology for locating interior and close-up improvements. These technologies will cost a significant amount of time and money to implement but municipalities, engineers and architects are going to be clamoring for the data any day now.

    When it comes to surveying and mapping of existing facilities, the surveyor and technology makes a great team. Do not let point clouds, remote sensing, or terabytes of data scare you away from providing badly needed information to help assemble your local digital twin. In the long run, it will pay off for all who take on the challenge of building it.