History of GIS at Spotsylvania County
The Spotsylvania County GIS Division, which is part of the Information Services Department, has been providing GIS services to the Spotsylvania County employees, citizens and businesses since 1993. The GIS Division is responsible for designing, developing, and maintaining the system and is staffed by a GIS Supervisor, a GIS Analyst 2 (dedicated to Community Development Group), and 3 GIS Technicians.
First GIS Ventures
The county’s first venture into GIS began when the paper tax maps were converted into a digital format using a heads-up digitizing approach. At that time, the data was stored and maintained in an AutoCAD Computer Aided Drafting (CAD) format. Since then, as properties on the maps have been divided, surveyed, or changed hands, the digital tax parcels were updated using a coordinate geometry (COGO) technique.
These newly created parcels were tied to survey points on plats, which created a highly accurate property fabric. Because of the extensive growth the county has realized over the past few years, much of the property has been surveyed and platted. However, in the rural areas of the county there has not been as much growth and subsequently the digital tax maps in that area were not updated and still reflect the positional accuracy anomalies inherited from the original paper maps. In numerous areas the non-updated, non-COGO’ed digital parcels do not accurately overlay the existing aerial imagery. This is a result of inaccuracies inherent in the mapping products, not by errors in the mapping process.
The base mapping layers were created from 1995 aerial imagery using a photogrammetric process. Some of the mapping features have been maintained over the years using information gleaned from site plans and property plats. We recently obtain from Virginia Department of Information Technology, 2013 6 inch resolution orthorectified aerial imagery.
The GIS Division maintains over 50 layers of spatial data that are managed using ESRI’s ArcSDE SQL Server Geodatabase product. The GIS Division performs most of the data capture and maintenance activities for the County.