- SPECIAL REPORTS
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In the fall of 1983, while an undergraduate at the University of Maine, I took a course titled “Cadastral Systems” in which the most fundamental theories of GIS were taught--even before the term GIS was created. Throughout the course, I learned about the importance of a precise control network and the implications of a meaningful cadastral layer. The following semester I saw my first personal computer: an Apple IIe with two 5¼ inch floppy drives, one for the program (goodbye punch cards) and one for the data.
About 10 years ago, I went to my first GIS software demo with a group of colleagues. Though impressed with how the system could recognize and manipulate many layers of geographic data, it quickly became apparent that the two essential elements of a GIS that I had learned about in the “Cadastral Systems” course, namely a precise control network and a meaningful cadastral layer, were missing. The system was simply a stitched-together assessor’s map viewed in conjunction with a scanned USGS quad sheet. Seeing blatant inaccuracies to the tune of hundreds of feet, I remember one older gentleman saying something to the effect of, “Well, our profession is safe. This stuff is useless.”
Applying GIS to Traditional PracticeTurning the clock ahead 10 years, I recently completed a graduate course in GIS at the University of Maine where I had the opportunity to put modern GIS through its paces. I found that the data is no longer inaccurate, that quality control has come to the forefront of GIS, and that survey grade geodetic control is now understood to be an essential underpinning to develop a GIS. Computing power has also made it so that nothing more sophisticated than a robust mail order computer is needed to run a GIS with ease.
For my final independent project in the course, I decided to see if I could use GIS to complete a surveying project. I was only three years out of private practice and understood that if a new technology can’t improve a company’s or organization’s operation, or provide added value to clients within a short period of time, then there is little or no chance of the technology being integrated into daily practice. Most surveying practices operate on a short business cycle and are subject to many external market-related pressures; therefore, committing large blocks of resources to long-term efforts with no short-term return is impractical. While searching for a surveying project to complete using GIS, it became apparent to me that if the GIS industry is going to engage the land surveying profession, focus has to be on short-term project-oriented applications with such long-term applications as records management as a secondary byproduct--not the other way around.
Finding the Right FitA perfect test case for my project was sitting in the corner of my office gathering dust. In 2004, a close friend of mine, John P. Droege, came to me with old maps, historical documents and a U.S. Department of the Interior mineral survey for the Johnny Bull, Phoenix and East Phoenix Gold Mine complex that his family had owned in the Sierra Nevada Mountains of California during the Gold Rush days.¹ The mine is long gone now, but as a family historian, Droege wanted to visit the area, if for no other reason than to be able to say he had followed in his ancestors’ footsteps.
In the summer of 2000, Droege first attempted to visit the mine site, but the rugged mountainous terrain kept him on the marked trails and unable to find the site. In my pre-GIS mind, I had planned to help Droege by generating a compiled plan based only on the mineral survey descriptions, with no field survey. The plan would be to scale and would have the look and feel of a modern survey.
By working in a GIS environment, however, I was able to do much more. I was able to start with reasonably high-resolution orthophotographs (aerial photographs used as maps from which distortions owing to camera tilt and ground relief have been removed) as a base plan. By including PLSS data from the Bureau of Land Management (BLM) Geographic Coordinate Data Base (GCDB), I was then able to seamlessly combine the mineral survey descriptions with the orthophotographs, municipal boundaries, Digital Elevation Models (DEMs) and USGS quad sheets of the area. Rather than just develop a single compiled plan, I was able to create an entire series of reliable maps to provide a comprehensive visualization of the mine area. I was also able to manipulate and include historical photos into the maps to aid visualization of the site. Though the mine was in California, I was able to do this all with publicly available data 3,200 miles away from the site. By varying scale, color, perspective, and carefully choosing which layers to depict together, I was able to better communicate survey information of the mine area to Droege and his family.
An Invaluable Layered ToolThough the series of maps makes a nice package for the Droege family, the value of the project for me came in becoming convinced that GIS is a tool that land surveyors can and should be using now. GIS can be used for creative projects, but more importantly, can be used to do many things that surveyors have traditionally done, only better.
For example, by easily snapping images at various zooms from the readily recognizable outline of the state of California, the first map in the series brings the East Coast viewer right to the site better than any other key map I have ever created. By orienting the mineral survey on the USGS quad sheet, the second map instantaneously communicates the nature of the terrain. Using the USGS quad sheet eases the viewer into the topography in a way that is both familiar and comfortable. The third map utilizes the available orthophotos to provide a perspective on nearby site detail very clearly. Any surveyor who has ever gone through the time and expense of procuring traditional photogrammetric mapping for generalizing site conditions will see that using publicly available orthophotography for such purposes can be economical. By including the PLSS lines in the various maps of the series, the user also has a constant scale reference. The next two maps bring the user right onto the ground of the site. Showing the specific site detail, again overlaid on the orthophotographs, users are able to get a good idea of what a site visit may be like.
Establishing 3D for Full ImpactThe final map in the series depicts the orthophotos draped over a DEM, which allows one to view the site in 3D. By combining the DEM, orthophotos, property line plans and a PLSS grid, and only manipulating the scale and viewing orientation, the topography--previously only viewable in 2D as the USGS quad sheet--is brought to life and the full impact of the terrain issues can be comprehended.
In the final phase of the project, I was able to confidently extract reliable geographic coordinates from the GIS for the boundaries of the mineral survey as well as for the former location of the buildings, mine shaft entrances, etc. I planned to load these coordinates into a handheld GPS receiver for use in navigating to the various points of interest on the site. Adding in historical photos of the buildings and the maps also allows users to see the scope of the entire project.
A Framework for IncorporationThe mapping of a gold mine in California is not a typical survey in many ways. In its most basic element, however, it is no different than, for instance, completing a title insurance survey of a complex site. In both instances, a work product that is technically sound but poorly communicated may deter the end user from truly receiving all the benefits from the surveyor’s work. When communicating my findings regarding occupation or encroachments, I can easily combine my measurements with readily available data sources in a GIS environment, and as a result, do my job better and be of greater service to my client.
The effort a surveyor would need to make to become competent in the use of GIS should not be minimized; however, I do not believe it is as enormous a task as the profession makes it out to be. In the same way that surveyors only use a handful of the tools available to them in their CAD packages, so too should they use GIS tools. Surveyors should not be intimidated by all that a GIS can do; rather, we should focus on how to get GIS to do what we want it to do.
GIS and Surveying: A New PerspectiveTo accept GIS and integrate this new tool into our daily practices, we surveyors must first master the basics to help us with the tasks we currently do. This includes integrating a survey with an orthophoto and incorporating it into a presentation, or combining a traverse or GCDB files with an orthophoto and a DEM for use in reconnaissance to aid in the search for evidence in remote areas. We should not be intimidated by all of the possibilities GIS brings. GIS has many tools that the typical surveyor will just never use. The surveying profession needs to move past any preconceptions and recognize GIS as an invaluable tool for surveying work.
For a variety of reasons, it is time for the surveying profession to become engaged in GIS. Based on my experience, we need to begin looking at GIS in a new light. GIS education for surveyors needs to be recast in a way that is hands-on. We need to direct practitioners to the aspects of GIS that can immediately be applied in their current practices on real projects, and provide a thorough foundation that an individual professional can build on when additional opportunities for the application of GIS present themselves.
On the Cusp of IntegrationThe future of GIS in surveying largely depends on if surveyors choose to embrace GIS in their everyday practices. Back in 1983, one professor at the University of Maine taught us about the role GIS should play in our perspective on the future of surveying. Down the hall, another professor simultaneously taught us about an additional technology still in its infancy that was believed to shape the future of surveying measurement: GPS. In the same way that GPS has taken its rightful place in the day-to-day practices of most land surveyors, it is now time for GIS to move from the fringe to the mainstream of land surveying practice.
Sidebar: Steps Toward Integrating GIS with Survey DataOne of the fundamental roles of a surveyor is to communicate matters of survey to his or her clients, public officials, courts, colleagues, abutters, etc. By integrating GIS with survey data, a surveyor can provide invaluable and understandable information by:
ï· Combining measurements with readily available data sources in a GIS environment.
ï· Integrating orthophotographs into a presentation for a client or municipal authority.
ï· Combining a traverse or set of Geographic Coordinate Data Base (GCDB) files with orthophotographs and a digital elevation model for use in reconnaissance to aid in the search for evidence in remote areas.
ï· Combining orthophotographs, survey data and archived cadastral records to automate retrieval and analysis in support of surveying technical and business functions.