Spatial Standards

Spatial Standards

Spatial Standards:

All features in our community can be located by some spatial coordinate. To visualize and evaluate geographic features in relation to adjacent features, a common coordinate system must be used for all data. Furthermore, GIS data are available in a myriad of formats, which are not always compatible with each other. It is necessary for geographic information to have properties, such as projection and datum, so that it may be used in a GIS environment. Richland County has established a set of fundamental standards to facilitate data comparison and exchange between the users of these data sets, both internal and external.

Projection: South Carolina State Plane*
Horizontal datum: NAD83 (North American Datum of 1983)
Vertical Datum: NAVD88 (North American vertical Datum of 1988)
Datum Conversion: NADCON
Unit of Measure: International Foot (SC Code of Laws Title 27 Chapter 2)

 

* As a federal installation, Fort Jackson must maintain data in the Universal Transverse Mercator (UTM) projection, Zone 17 based on NAD27. Several SC State Agencies also maintain their data in UTM projections. It was agreed that a different projection/datum for local and other data was not an obstacle as long as the conversion method was standardized. Thus, it was agreed that all datum conversion would be done using NADCON (as opposed to three and seven parameter versions of Molodensky or Bursa-Wolf transformations).

Vector data: ESRI-compliant geo-relational model (i.e., ArcInfo coverages, ArcInfo E00 export files, ArcView shapefiles and Spatial Database Engine layers), as well as AutoCAD’s DXF.

Raster data: ERDAS .LAN, Mr. Sid, JPEG, GIF, TIFF, GeoTIF, and BIL.

Tabular data: INFO, Dbase, ASCII text delimited and ODBC compliant RDBMS tables.

Metadata: FGDC compliant for each layer.