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This doesn’t mean that we must stop performing retracement and boundary surveys. It only means that such work is but a small percentage of the entire menu of work that is available for us. It is a fundamental fact that every parcel of land in the United States has been identified and linked with ownership to one party (or, in cases of disputed boundaries, two parties). All of this information is put together in one place in the GIS, and the foundation for a GIS is its parcel map. It is important to remember that the GIS parcel maps that are maintained by the local government taxing authority were created or, in most cases, scanned from hand-drawn tax maps. As a result, these GIS parcel maps were simply cartoons when first created that showed the geospatial juxtaposition of all parcels within a jurisdiction to each other. Accordingly, all GIS parcel maps are a work in progress and growing more accurate as better ground truth is added.
Regarding a GIS that works for relatively precise location of parcel boundaries, consider that orthographic aerial photography is now available in many venues that is accurate to within one foot of the actual location of physical objects. The upgrade in this science has created a perceived problem for government entities that are maintaining a GIS parcel map that won’t properly overlay the aerial photography. It is also of interest that almost every parcel has road frontage or road access and that the observed centerline stripe is, in most cases, a good approximation of the centerline of the right-of-way. Software now exists that can automatically identify the state plane coordinates of those centerline stripes from the orthographic aerial photography, and the GIS software can rectify the parcel locations to those locations. Accordingly, many jurisdictions now have a GIS that overlays the aerial photography more precisely.
A realization that this is taking place and that it cannot be stopped will make the thoughtful surveyor change with this transition. Like it or not, the horizontal and vertical position of parcels that can be determined from the local government GIS is well along its way to becoming a reality. We must take our heads out of the sand and begin to expand our markets. Failure to do so will only result in a surveyor’s obsolescence.
What do you think? Are there new opportunities on the horizon for the surveyors willing to embrace them? Please share your comments below.
Additional discussion on this topic can be found at www.rpls.com.