Using these simple tools, repeated measurements, and lots of patience, George Washington produced some amazingly accurate maps, eventually completing hundreds of separate surveys to transfer ownership of property from the Crown to the citizenry. Half a century later, when John Charles Frémont set about to map the passes and measure the mountains of the expanding western frontier, surveying technology had not advanced much beyond what Washington would have used.
Today, however, satellites circle the globe continuously collecting high-resolution data; piloted aircraft roam the skies with digital cameras and laser-based sensors; and vehicles drive the roads collecting 360° images. And, from time to time, human beings still walk around and look through lenses and point their data collectors at objects on the ground. From all of these sources, multiple types of data are collected and processed, and maps are made – oftentimes without drawing anything on paper. Clearly, the technology and art of map-making have advanced exponentially since the days of the frontier surveyor. However, the basic math and science behind the art remain the same. This is why the maps produced by Washington and Frémont (and others) were so stunningly accurate, when compared to present day technologies.
In Washington’s day, surveys consisted of metes and bounds – simple compass directions (in degrees) and distances (in chains). This was a cumbersome system to describe vast ownership tracts as the U.S. expanded westward. Congress created the Public Land Survey System (PLSS) in the Land Ordinance of 1785, to identify land for titles and deeds. Still in use today, the PLSS consists of a 6-mile by 6-mile grid, the east-west lines being referred to as Township lines, and the north-south lines being referred to as Range lines. Each of these blocks is divided into one-square-mile Sections, numbered 1 through 36, each containing 640 acres. Hence the term 16th Section to refer to that portion of every Township/Range block set aside for public education.
In 1812, the General Land Office (GLO) was tasked with developing and archiving these surveys. These GLO plats – carefully surveyed, then scribed with great detail – are almost works of art. Minimum accuracy was specified at one chain (66 feet) per mile, and surveyors in the 1830s were paid $2 per mile of line surveyed. In Mississippi, for instance, it took approximately 1,400 GLO plat maps to cover the state. As a direct benefit of our digital age, you and I may now access these plats online, along with the original deeds to individuals from the United States government.
The image below is of the original GLO plat of Township 7 South – Range 6 West in Mississippi, covering the marsh areas of the Lower Pascagoula Basin, and shows the relative accuracy of the original GLO surveys (hand lettered and water colored) to the corrected digital Section lines (shown in green). As points of reference, the City of Moss Point is in the upland areas on the east (left) side of the map, and Interstate 10 runs east-west across the map just above the junction of Creole Bayou with the Pascagoula River. Note that no Section lines were surveyed in the center portion of the map. In that area, the notation reads, “Pascagoula Bay – Interspersed with Islands and marsh, which render it impassable and entirely overflows in high tide water”.
Although the GLO plats were extremely accurate for their time, modern technology, such as airborne digital sensors and Global Positioning Systems (GPS), allow for collection of detailed data that augments the original survey information and allows for these plats to be corrected and displayed in digital projections.
Through the 19th and 20th centuries, improvements in the accuracy of survey-produced maps resulted primarily from advances in the technology of the lenses and mechanics of the survey instruments in use at the time. Production of the actual map from the surveyed data was still a manual process. Even in the 1970’s some of us were still mapping hundreds of thousands of acres of timberland in southwest Mississippi by looking through stereo glasses at side-by-side pairs of black and white photographs and scribing lines on acetate overlays.
Two amazing advancements emerged about this time that would change the surveying and mapping industry forever. One was the use of lasers for commercial grade applications, and the other – the advent of desktop computing.
In the early 1960s, technologies began to combine laser-focused imaging with radar’s ability to calculate distances by measuring the time for a signal to bounce off an object and return to the sensor. Early applications were in meteorology, when the National Center for Atmospheric Research used it to measure clouds. The general public became more aware of the accuracy and usefulness of such systems in 1971 during the Apollo 15 mission, when astronauts used a laser altimeter to map the surface of the moon. The surveying industry found quick application for this emerging technology by using a laser beam to measure the horizontal distance between two fixed points. This electronic distance measurement (EDM) technology began to replace the standard transit and chain method of establishing and measuring lines in the field. It was only a matter of time until airborne application of the same principles began to revolutionize the collection of ground elevation data over large areas. This occurred through the advent of LiDAR (Light Detection And Ranging) technology. And, of course, with the development of desktop computing, the ability to develop such data derived from these electronic surveying methods revolutionized the process of map production. Maps were no longer limited to two-dimensional images on paper but now could be produced in multiple dimensions and stored electronically, all at the click of a button…well, maybe not that simply, but you get the picture.
In the 1980s, as desktop computing became more and more accessible, CAD (Computer-Aided Design) and digital mapping hit the industry by storm. This unleashed a tidal wave of opportunity to transfer existing paper maps to digital. Hardware vendors continued to improve digitizing equipment, with manual digitizing tablets giving way to automated scanners. A new industry for map encoding and database design emerged, as well as a marketplace for the sale of digital map products.
Much of this new data has become a part of our everyday lives through our various digital devices. We pull up a street location in Google Earth on our tablet and “stroll” around our neighborhood. If you look at the numbers at the bottom of the screen you also see your exact location on the face of the earth – latitude, longitude, and elevation. We pull up MapQuest on our smart phone to plan a business trip or vacation, and instantly have a map depicting the best route along with estimated driving time. We take for granted that the apps we use are accurate and up-to-date, but behind the technology that makes our lives so much easier, are companies that collect and update the digital data sets that drive the apps. Some of these applications use data sets collected through initiatives sponsored by the State of Mississippi.
For example, Mississippi’s first statewide effort to collect high-resolution imagery took place in 2005 sponsored by the Department of Environmental Quality, Department of Transporation, and the Mississippi Coordinating Council for Remote Sensing and GIS, among others. Soon thereafter, the state began collecting LiDAR-based 3D ground surface data. Since then, LiDAR data have been collected over 80 percent of the state, allowing the development of 2 foot, or even 1 foot interval ground elevation contour lines. This high-resolution coverage now replaces the older 10 foot (or greater) contour lines developed decades ago by the U.S.Geological Survey. Engineers, planners, and developers across the state have found application for these new digital elevation models in various areas; for example, easier design of roads and bridges, identification of optimal routes for new transportation corridors, improved mapping of flood risks and other hazards, and advanced planning for major economic development sites.
So where is technology currently taking the fields of surveying and mapping? More important for those of us in the business of engineering, surveying, and mapping, what trends are impacting the direction of our business, and how must we respond to remain relevant? There are lots of things going on, but two particular advancements are of particular note.
One trend we see is the general availability of Web-based data that is propelling the field of surveying and mapping into uncharted territory. Designers, developers, and public works directors will always have the need for high-resolution, localized survey data for engineering-grade design and construction; and, there will always be a place for desktop-based applications. However, web-based data will undoubtedly play an increasingly significant role in providing more efficient, readily accessible, and less costly data to those end users who don’t necessarily need engineering-grade data for solutions to their daily challenges. This, in turn, makes digital mapping more cost effective for owners. City, county and state agencies can share data more readily among themselves and with the public. A rural county that might not have a large tax base and a correspondingly large budget can more easily and affordably embrace the benefits of digital mapping.
A second trend, perhaps more ‘flashy’ has to do with unmanned aerial vehicles, or systems (UAVs or UASs), more popularly referred to as drones. Most of the press about these systems has to do either with the large scale models use in real-time military applications, or about amateurs using smaller versions in some recreational and often dangerous location or manner. However, a vast amount of research is presently underway using UAVs for purposes that will make our daily lives richer, and some Mississippians are leading the way in this effort. Mississippi State University was recently selected to lead a 13-university consortium to conduct UAV research with applications from agriculture to real estate development to homeland security. Advances in UAVs and the digital sensors they can carry has the potential to propel the business of surveying and mapping into realms of incredible accuracy, timeliness, and availability that we could not have dreamed of even ten years ago.
Technology has greatly changed our perspective of the map. From a two-dimensional representation of historical information, a map can now be a three-dimensional, interactive and intelligent decision-making tool. Today’s professional is challenged to understand this new environment and formulate innovative applications that meet the complexity and accelerating challenges of the 21st Century. Three centuries ago young, talented, pioneering young people used their talents and a few simple tools to literally map the nation’s frontier. Today, young, talented, enterprising young women and men are emerging from our colleges and universities to lead the way in striking out along the forward edge of a new frontier. However, the tools of their trade are no longer the compass and chain, but rather satellites, ‘clouds’, mobile technology and even social media.
» Bill McDonald, PE, and Cragin Knox, PG Engineered For Success is an occasional column on the latest trends, issues and perspectives facing the engineering, economic development and project management industry, written by members of the Waggoner Engineering team.
BEFORE YOU GO…
… we’d like to ask for your support. More people are reading the Mississippi Business Journal than ever before, but advertising revenues for all conventional media are falling fast. Unlike many, we do not use a pay wall, because we want to continue providing Mississippi’s most comprehensive business news each and every day. But that takes time, money and hard work. We do it because it is important to us … and equally important to you, if you value the flow of trustworthy news and information which have always kept America strong and free for more than 200 years.
If those who read our content will help fund it, we can continue to bring you the very best in news and information. Please consider joining us as a valued member, or if you prefer, make a one-time contribution.Click for more info