About GIS and its Uses
Southside Planning District Commission uses Geographic Information Systems (GIS) to produce maps (paper and electronic version) and GIS data.
A GIS system utilitizes some type of geographic database (a shapefile of Census blocks, for example) that is at its core joined with a database (such as an Access database containing the actual Census data). GIS can be used for everything from mapping water and sewer lines to helping with redistricting.
The GIS at SPDC is used to produce maps and data to support the grant process, both in the applications for the grants as well as information needed during the administration of the grant project.
In addition, SPDC uses GIS to produce data needed for comprehensive planning and other activities. GIS is used to provide demographic data for SPDC use as well as localities and the public.
GIS Project Deliverables
Most GIS projects undertaken at SPDC result in any number of the following deliverables:
- cartographic maps (paper and electronic, typically PDF)
- GIS data (ESRI geodatabase, shapefile, KML, etc), or
- spreadsheet/table data (Excel, Access)
GIS data used by SPDC GIS staff typically is either created in-house using some type of digitizing process, or is obtained from outside sources such as the Commonwealth of Virginia or one of the Counties. Very rarely do we obtain GIS data from commercial sources.
GPS (Global Positioning Systems) Mapping is accomplished by using a survey-grade GPS RTK system. Under the proper conditions this system has accuracy of a centimeter. We use it to obtain geospatial data on utility systems and transportation infrastructure.
Cartographic Map Production
Cartography differs from typical GIS work in that cartographic maps are typically thought of as "pretty maps."
National Geographic maps are an excellent example of high-level cartography, where much effort has been put into labeling, colors, legends, and overall look and feel of the map. On the other hand, a screenshot of a GIS program displaying a tax parcel boundary with no labeling, over an aerial image, with no title, legend, or scale presented is not an example of cartography.
Google Maps and Google Earth are not great examples of cartography, as all the labeling is done automatically, although the algorithms are pretty good and the line between cartography and basic GIS maps is becoming more blurry as time goes on. (Examples of Cartography, GIS and Google maps)
SPDC GIS staff try to uphold high standards of cartography for most projects that call for a printed or electronic map. We are by no means experts in the art of cartography, but we do strive for the best maps possible within a given timeframe.