Tag: GIS databases

Surveyors: Always in the ‘middle’ of something…

The surveying profession is intrinsically involved with many functions of today’s communities and environment. When we take a closer look at the roles we play, the surveyor is usually found in the middle. Here are a few examples.

For new developments and infrastructure, surveying takes place after a client decides to begin a project. Site data must be collected, drafted and presented to the client, engineers and architects for design.
Upon completion of the engineering design, the surveyor provides layout services for the construction company to build the structure.
Once the improvements are completed, the surveyor provides surveys as well as record drawings for confirmation of construction to satisfy government agencies and financial backers.
In a property dispute, the surveyor becomes the center of attention — our professional opinion determines the correct location of the subject boundary.

This responsibility also extends to the geospatial sectors within the surveying profession. Data collection is a critical step to creating and maintaining efficient geographic information system (GIS) databases that correctly depict existing infrastructure and parcel boundary layers. With the surveyor at the center of many of these duties and tasks, no wonder that we sometimes feel we have a bullseye on our backs.

Knowing how to compute the center is an important aspect of the surveyor’s duty.

However, the word center takes on a different connotation when it comes to data and objects. Properly identifying the center of specific sets of data or objects is important when working with construction information and geospatial data. Properly measuring and marking the center of an installation has its challenges, so knowing how to compute the center is an important aspect of the surveyor’s duty.

Why is the center of an object important?

Every object that is definable in a two-dimensional space has a physical center. Whether the object is a regular or irregular polygon in plane geometry, there are various methods for determining its center.

These figures are easy to understand and simple to solve. More complex figures require more calculations, including coordinate geometry.

These examples of regular and irregular polygons have something in common: all are based upon two-dimensional space, which is flat. But what happens if we need to determine the center of a shape that does not fall on a 2D surface? What if the data being reviewed for a center resides on a spherical surface and contains diverging axes?

As surveyors, we break our work down to smaller coordinate systems to work around the fact that our data resides on a spherical surface, but some datasets require the information to remain as latitude and longitude. One dataset is population counts, otherwise known as the census.

The U.S. Census and the ‘center of population’

The U.S. Census Bureau has been at work since early colonial times. This excerpt from the bureau website explains its purpose and foundation.

The U.S. Constitution requires only that the decennial census be a population count. Since the first census in 1790, however, the need for useful information about the United States’ population and economy became increasingly evident.

The decennial census steadily expanded throughout the nineteenth century. By the turn of the century, the demographic, agricultural, and economic segments of the decennial census collected information on hundreds of topics. The work of processing these data kept the temporary Census Office open for almost all the decades following the 1880 and 1890 censuses.

Recognizing the growing complexity of the decennial census, Congress enacted legislation creating a permanent Census Office within the Department of the Interior on March 6, 1902. On July 1, 1902, the U.S. Census Bureau officially “opened its doors” under the leadership of William Rush Merriam.

Counting the citizens of the United States was one thing, but mapping them was another. Once the final count was completed and mapped, the information was used to determine a unique location: the center of population. Here is more from the Census Bureau on the calculation basis:

The concept of the center of population as used by the U.S. Census Bureau is that of a balance point. The center of population is the point at which an imaginary, weightless, rigid, and flat (no elevation effects) surface representation of the 50 states (or 48 conterminous states for calculations made prior to 1960) and the District of Columbia would balance if weights of identical size were placed on it so that each weight represented the location of one person.

More specifically, this calculation is called the mean center of population.

This sounds like an easy exercise for a room of mathematicians and mappers, right? On the contrary, my fellow geospatialists!

How do they determine the center of population?

Computing the center of population for the United States would be much easier if we existed on a two-dimensional plane, as previously discussed. Since we don’t, however, it requires a much more difficult method of calculation to get us closer to a real-world solution:

To avoid unduly complex factors in the computations, the mathematical formulae used were those that would be precise for a true sphere. On such a sphere, the north-south distances between parallels of latitude are identical and distances in degrees may be used as units of distance. On the other hand, distances between meridians on longitude lines are not constant but decrease from the equator toward the poles. However, if the length of one degree along the equator is used as the unit of measurement, then the length in degrees of an east-west line at any other latitude can be adjusted to the measurement standard by multiplying by the cosine of the latitude.

The center of population computed by the Census Bureau is the point whose latitude (𝜙) and longitude (λ) satisfy the equations:

where 𝜙𝑖, 𝜆𝑖 and 𝑤𝑖 are the latitude, longitude and population attached to the basic small units of area used in the computation.

Stated in less mathematical form, the latitude of the center of population was determined by multiplying the population of each unit of area by the latitude of its population center, then adding all these products and dividing this total by the total population of the United States. The result is the latitude of the population center.

East-west distances were measured, or computed, in substantially the same manner, but with the inclusion of a correction for latitude. For these distances, a degree of longitude at the equator was the unit of measurement. East-west distances along the equator could be measured in degrees, but any east-west degree distance north of the equator — where all the United States is located — had to be adjusted to recognize the convergence of meridians toward the poles. This adjustment required that each east-west distance, stated in degrees of longitude, be multiplied by the cosine of the latitude. This mathematical relationship is precise for a sphere and a very close approximation for the earth.

The computation required that the longitude of each of the thousands of selected points be multiplied by the cosine of the latitude of the point and by the population associated with the point. These products were added and divided by the sum of the products for the same thousands of points, each of which was obtained by multiplying the cosine of the latitude of a point by the appropriate population figure. The result was the longitude of the center of population.

(Courtesy of the Geography Division, U.S. Census Bureau, published November 2021)

Here is a graphic from the U.S. Census identifying significant historical events along with the westward movement of the center of population:

Here are the locations with corresponding latitude/longitude for the centers from 1790 to 2020:

Mean Center of Population of the United States, 1790–2020
Census year	North latitude	West longitude	Approximate location
*United States*
2020	37.415725	92.346525	Wright County, MO, 14.6 miles northeast of Hartville.
2010	37.517534	92.173096	Texas County, MO, 2.7 miles northeast of Plato.
2000	37.69699	91.80957	Phelps County, MO, 2.8 miles east of Edgar Springs.
1990	37.87222	91.21528	Crawford County, MO, 9.7 miles southeast of Steelville.
1980	38.13694	90.57389	Jefferson County, MO, 1/4 mile west of DeSoto.
1970	38.46306	89.70611	St. Clair County, IL, 5 miles east-southeast of Mascoutah.
1960	38.59944	89.20972	Clinton County, IL, 6-1/2 miles northwest of Centralia.
1950	38.80417	88.36889	Clay County, IL, 3 miles northeast of Louisville.
*Conterminous United States*
1950	38.83917	88.15917	Richland County, IL, 8 miles north-northwest of Olney.
1940	38.94833	87.37639	Sullivan County, IN, 2 miles southeast by east of Carlisle.
1930	39.06250	87.13500	Greene County, IN, 3 miles northeast of Linton.
1920	39.17250	86.72083	Owen County, IN, 8 miles south-southeast of Spencer.
1910	39.17000	86.53889	Monroe County, IN, in the city of Bloomington.
1900	39.16000	85.81500	Bartholomew County, IN, 6 miles southeast of Columbus.
1890	39.19889	85.54806	Decatur County, IN, 20 miles east of Columbus.
1880	39.06889	84.66111	Boone County, KY, 8 miles west by south of Cincinnati, OH.
1870	39.20000	83.59500	Highland County, OH, 48 miles east by north of Cincinnati.
1860	39.00667	82.81333	Pike County, OH, 20 miles south by east of Chillicothe.
1850	38.98333	81.31667	Wirt County, WV, 23 miles southeast of Parkersburg.
1840	39.03333	80.30000	Upshur County, WV, 16 miles south of Clarksburg. Upshur County was formed from parts of Barbour, Lewis, and Randolph Counties in 1851.
1830	38.96500	79.28167	Grant County, WV, 19 miles west-southwest of Morefield. Grant County was formed from part of Hardy County in 1866.
1820	39.09500	78.55000	Hardy County, WV, 16 miles east of Moorefield.
1810	39.19167	77.62000	Loudoun County, VA, 40 miles northwest by west of Washington, DC.
1800	39.26833	76.94167	Howard County, MD, 18 miles west of Baltimore. Howard County was formed from part of Anne Arundel County in 1851.
1790	39.27500	76.18667	Kent County, MD, 23 miles east of Baltimore.

Data: U.S. Census Bureau

Not to be confused with the geographic center…

The geographic center of area is the point at which the surface of the United States would balance if it were a plane of uniform weight per unit of area. That point, approximately 44.967° north latitude and 103.767° west longitude, is located west of Castle Rock in Butte County, South Dakota, as it has been since Alaska and Hawaii became states.

The geographic center of the conterminous United States (48 states and the District of Columbia) is located near Lebanon in Smith County, Kansas, at approximately 39.833º north latitude and 98.583º west longitude.

The center of population as geospatial data

The plotting of the center of population makes for an interesting study of westward expansion in early U.S. history. Once the contiguous 48 states were founded, plotting the center shifts to regional changes . The truly interesting part of these calculations and plotting for the past several centuries falls into an area of expertise called geospatial data.

While some liberties were taken early on using large, populated areas as one data point, we now can count literally every person and their geospatial location. However, it needs to be recognized that early efforts to count our population and track its center every 10 years meets the criteria for being called geospatial data. They just didn’t yet know what that meant.

Speaking of surveyors…

Here are several events and initiatives happening this month, an important month for surveyors.

2022 National Surveyors Week

National Surveyors Week was established by the National Society of Professional Surveyors as an annual event to bring public recognition to the surveying profession and the vital services surveyors provide to the advancement and betterment of human welfare.

During this week, thousands of professional surveyors throughout the country will take part in local activities designed to introduce a new generation to the profession and highlight the use of technology in their day-to-day work.

Activities for National Survey Week (or anytime!)

Have a Survey Day at your local mall.
Sponsor a Trig-Star Test: www.trig-star.com.
Conduct a Scouts Merit Badge event.
Obtain a proclamation from your state or local government.
Organize geocaching or benchmark hunting: Geocaching.com.
Try surveying mark recon: SurveyMarkHunting.pdf.
Help with the National Geodetic Survey’s GPS on Benchmarks Campaign: GPS on BMs

For more ideas on how to get involved, visit National Surveyors Week 2022.

2022 Global Surveyors’ Day

Global Surveyors’ Day 2022 will be held Monday, March 21. This annual event is a way to globally recognize groundbreakers, pioneers, individuals and the industry that has shaped our history and continues to be of great value to our communities.

2022 Global Surveyor of the Year

As part of the Global Survey Day and National Surveyors Week, every year on March 21 a professional surveying association is tasked with choosing a Global Surveyor of the Year. For 2022, the National Society of Professional Surveyors has been selected to choose a person with a historical surveying background for this prestigious honor. After thorough consideration, NSPS has chosen Benjamin Banneker (1731–1806) for 2022 Global Surveyor of the Year.

The selection was brought before the NSPS Board of Directors during our Spring 2021 meeting and passed by a majority vote. While Banneker’s career as a surveyor was limited in time and experience, his additional contributions to math, science, astronomy and publication of a groundbreaking almanac have earned him a significant place in American history.

We also selected Banneker because of his ability to overcome the adversity of being a free Black man in early colonial America. Through much self-teaching, he was able to excel at the contributions previously listed in a period when Blacks were not accepted for their educational abilities.

The selection committee chose Banneker over the three presidents who are famously chiseled on Mount Rushmore and Henry David Thoreau, an author who also surveyed to fund his writing career. The committee felt that Banneker’s contributions not just to the surveying profession made him deserving of this honor, but considered his total body of work created when Black men were not generally accepted as capable human beings. Our world needs more people like Benjamin Banneker and would be a better place because of them.

No time like the present to promote our geospatial professions

Surveying and geospatial careers are more important than ever, so examples like the center of population help depict applications that us these skills. Please consider promoting our wonderful professions during these events and throughout the year. The profession you promote may provide an opportunity to bring new faces and ideas to our ranks very soon.

March 2, 2022

Surveyors and their global role as humanitarians
Every year, surveying associations worldwide celebrate Global Surveyor’s Day during the third week of March. This year is no different (even during a pandemic) and will be recognized on Tuesday, March 23.

While this past year has been full of challenges, the role of the surveyor on a global scale has continued to grow. As a professional land surveyor in the midwestern portion of the United States, my surveying experiences have been wide-ranging at times.

For those who know of me and/or have followed my writings here in GPS World, you probably understand how my perspective for the surveying profession has come to be. For those who have no clue about my background, let me give you a brief refresher:
- Second-generation surveyor, born and raised in Central Illinois, United States
- Surveyed in rural, suburban and urban environments
- Began writing for GPS World in 2015 to share my surveying perspective
Even though my surveying career has spanned several decades, my experience has been limited to the areas described above. From my early days of spending hours in the county recorder’s office pouring through tract index books, all the way to viewing parcel shapes, scanned documents and high-resolution aerial imagery in today’s world, it seemed at face value that my experience covered most of the duties of the typical land surveyor.

My career has encountered robotic total stations, all iterations of GPS/GNSS data collection, laser scanning, and now UAV data collection. Throw in the development of the personal computer, COGO and CAD software, the Windows operating system, pen plotters, and countless software breakthroughs, and my perspective of the surveying profession had been front row for all the great things we now take for granted.

However, these advancements, in tandem with growing up in middle-class America, did not prepare me for a recent experience with a surveying/geospatial group new to me.

VCSP Wisdom Workshop

A virtual workshop was recently held to discuss the Volunteer Community Surveyor Program (VCSP) instituted in 2017 by the International Federation of Surveyors (FIG) and the FIG Young Surveyors Network (YSN). More than 125 attendees from worldwide locations logged into the sessions to learn about the program and how to become involved.

The program, titled “Sustainable Solutions for Land Based Community Problems: Tools and Modern Approaches,” spanned two days and two four-hour sessions. Before we jump into the specifics of the program, first we will offer another brief refresher on FIG and its YSN.

The Fédération Internationale des Géomètres, now known to English speaking nations as International Federation of Surveyors, was founded in July 1878. It has grown into a worldwide non-governmental organization representing more than 120 countries and their surveying/geomatics professions.

The National Society of Professional Surveyors (NSPS) is a member organization and participates at various levels throughout FIG.

The FIG Young Surveyors Network (FIG YSN) was initially established in 2006 as a working group, and upgraded in 2009 to network status due to its rapid growth. This group of young professionals and practitioners worldwide has worked with groups such as the United Nations, World Bank, National Society of Professional Surveyors (NSPS) and Council of European Geodetic Surveyors (CLGE) to promote the profession, increase opportunities for young professionals, and be an agent for social and climate change.

This YSN workshop set lofty goals, including providing information about the VCSP as well as informing participants of the current means and methods of surveying in underdeveloped countries. For context, here are the program topics covered over the two days:

DAY 1: Community problems, land tenure and tools for land management
- Experiences and opportunities of humanitarian surveyors (past volunteer community surveys)
- Land management, community development and open technologies
- Identifying the relationship between land management and community development
- The skills of a humanitarian surveyor
- Introduction to STDM and Cadasta tools
- An implementation of the STDM and Cadasta tools for land management
DAY 2: Building capacity and implementing modern land-management approaches
- Leveraging land-management tools for problem solving and decision making
- Designing country-scale solutions for land rights and tenure security issues
- Gathering resources for land management projects
- How much have land rights and tenure insecurity impacted your country?
- Documenting and publishing experiences
- What’s next? Parallel sessions by FIG region
Introduction to the humanitarian surveyor

Like most land surveyors in the United States, our role has been well-defined for generations. We establish and/or reestablish parcel boundaries (that is, original or retracement surveys). While our duties have expanded based upon technology, the central responsibility of the surveyor has been established as an expert measurer and provider of boundary information.

In the 200+ years since the westward expansion and formal establishment of most of the United States, the role of the surveyor has evolved into more of a commercial purpose. A surveyor’s principal responsibility is to protect the public, but that meaning has much different connotations in lesser developed countries.

FIG Volunteer Community Surveyor working with locals to discuss parcel possession. (Photo: FIG Young Surveyors)

In the recent past, surveying efforts in many developing countries have been like the early General Land Office surveyors in the 1800s. A surveyor in these regions is out in front of development of unclaimed lands, observing natural and manmade boundaries to guide the decision-making process in establishing parcel rights. The methods and procedures used to date in many lesser developed countries are much like 19th-century surveying — primitive instruments and crude maps sketch property claims with little to no authority.

Surveying: The Next Generation. Here is where the concept of the community or humanitarian surveyor comes into the picture. A new generation of surveyors is using modern technology not just to map existing boundaries and improvements, but also to collect additional data that will be analyzed to help improve living conditions. With the introduction of GNSS technology, establishment of parcel boundaries now takes an accurate and precise shape in GIS databases created for improving conditions in these areas.

Additional attributes are collected to determine utility needs, communication availability and access to medical care.

The easy solution seems to be that, as a larger part of the surveying community, we send teams of surveyors to these countries to locate and establish boundaries as well as perform site studies to determine living conditions and potential improvements. If it were just that easy…

Local government: Friend or foe?

Often, these surveyors are going into regions where the local or national governments do not agree with empowering their citizens with property rights and allowing them access to basic utilities. Part of the humanitarian surveyor’s role is to get to know the “lay of the land” when it comes to local order.

Many remote places are controlled by local gangs, tribes or other factions. These groups forbid the population around them to own their property. Even though it may seem like these physical parcel boundaries exist, most of these people do not have title or land tenure rights. This is partly because of the local control situation, but can also be due to the lack of sophistication within the local or national government.

Communication hurdles. Another hurdle for the humanitarian surveyor has nothing to do with their professional capability — it relies solely on appearance, body language and ability to bridge a communication gap. For example, most first-world nations rely strictly on communication skills and the competence to effectively work with other people. We often easily trust those who present evidence of competency with no previous interaction.

In third-world countries, however, locals do not trust outsiders and place competency on those who have built long-term relationships with them. They also rely heavily on body language and facial expressions to convey trust. Local citizens in these areas are less likely to trust visiting older generations who are not able to understand these visual cues.

Combining the factors of trust of the local citizens with the unsteadiness of government and/or lawlessness, the humanitarian surveyor must also be able to determine common property lines, locate lines of occupation, and remain neutral in providing guidance to adjacent neighbors. These conditions often include areas for crops and livestock, as well as places for food growth and development.

With little to no money and lack of commerce available, many of these regions are food poor. Locals are forced to harvest their own food, so having a plot of land to grow these crops is critical.

The surveying procedure for the VCSP. (Image: FIG Young Surveyors)

In more established areas, it can be challenging to determine land tenant rights with many shanties and lean-tos being joined structurally. It is equally difficult to determine if any common utilities exist in these areas, such as stormwater channels to help with rainfall.

Add to these improvement location duties the need for better census data to help with government analyzation of population to apply for aid from other countries.

The good thing is that technology has progressed in creating tools for geographically locating all these entities, including population, with a multitude of attributes to complete proper analyzation. But there is a catch.

Technology challenges worldwide

One of the biggest issue surveyors face when providing services in these areas is the lack of advanced technology and computers. These areas may not have reliable utilities, such as electricity or running water, much less viable internet or Wi-Fi. If computers do exist with local government, they are often years behind in computing power and software. Even operating systems like Windows are a rarity in many of these countries.

Networking accuracy needed. Most humanitarian surveyors will bring their own equipment and computers, so that problem can be averted. But what about geographical locations? Yes, GNSS constellations are available worldwide, but accuracy using just satellite signals is not sufficient for location of parcels and improvements.

To get survey-grade accuracy, the surveyor will typically utilize a correction service or base station on a known value. Most of these corrections are based on Continuously Operating Reference Stations (CORS) or similar established reference stations, so creating a georeferenced datum for the surveyed location takes time and knowledge. Once the network is established, lots of work and oversight is necessary to provide quality control on the data being located.

Tackling parcel management on a global scale. (Image: FIG Young Surveyors)

To add to these issues, most of the staff necessary to complete the surveys must be brought in due to the lack of education at the location. The role of the humanitarian surveyor will also be to teach the craft of surveying to locals, who will continue to expand the area cadaster after the volunteer surveyor has left.

Open-Source Software. However, affording the necessary equipment, computers and software to continue the newly established system is also a hurdle for the community. While the price of computer hardware has greatly reduced over time, the advancement of software and cost of upkeep provides a greater monetary challenge.

Enter open-source software, based upon Linux and other free computer operating systems. This software has been developed with these situations in mind. It allows for customization to each user’s specific need. There are several GIS and data-collection platforms to fit the needs of these budding communities and countries. Open-source and public-domain software allow even the most basic of cadaster needs to be completed efficiently.

Young surveyors network to the rescue

From a technology standpoint, it makes sense that the FIG Young Surveyors Network began this program to help underdeveloped nations begin to create simple cadasters for assessing their property and improvement needs. The younger generation has grown up with technology and can easily teach someone how to embrace it and trust the results.

This younger generation is also the developer of open-source software and tools and sees the value in providing low- to no-cost applications to those who need it most. While the hard part is collecting the data and working with the locals to establish common boundaries, count the population, and determine the utility needs, they take pride in being part of a solution for a segment of the world that may not have any other chance or choice.

Participants in the Volunteer Community Surveyor Program (VCSP). (Photo: FIG Young Surveyors)

One of the interesting portions of the workshop was the breaks between segments. While it was a time to step away from the computer/tablet/phone, the organizers broadcast videos of musical groups from around the world and encouraged the participants to stand up and dance, with their cameras on. While I did not partake in the dancing (it was 4 a.m. at my home), I applaud the Young Surveyors for providing a welcoming atmosphere where each person could be themselves. Several of the participants were in Africa and Asia on cellphones, so creating a workshop environment that worked for all levels of engagement was fascinating.

What I learned

My biggest takeaway was simply learning about the term “humanitarian surveyor.” My earlier reference trying to relate these volunteers to the GLO surveyors, while in the same vein in establishing land boundaries, misses badly in terms of overall contribution to the communities in which the volunteers visit.

The work they perform is truly humanitarian. While I have tried to comprehend the conditions they are facing, I again fall short in fully experiencing what the role has to offer.

One of the testimonials was regarding a group that went to Nepal following the 2015 earthquake to help re-establish towns and parcels. The pictures were stunning, and the memories shared were heartfelt. To be one of these volunteers is truly a humanitarian effort.

Well done, FIG Young Surveyors Network and the Volunteer Community Surveyor Program. I will do my best to not take life here for granted anymore.
March 2, 2021