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. The City of High Point has established a set of fundamental standards to facilitate data comparison and exchange between the users of these data sets, both internal and external.
Spatial Data Standards for the City of High Point include:
- Projection: North Carolina State Plane 3200 FIPS
- Horizontal Datum: NAD83 (North American Datum of 1983)
- Vertical Datum: NAVD88 (North American Vertical Datum of 1988)
- Datum Conversion:NADCON
- Unit of Measure:Feet
- Vector data:ArcGIS Spatial Database Engine features, ArcGIS shapefiles, AutoCAD DWG & DXF.
- Raster data:ERDAS img, ENVI; hdr, Mr. Sid, JP2 (JPEG 2000), TIFF, GeoTIFF.
- Tabular data: Dbase, ASCII delimited, ODBC compliant RDBMS tables.
- Metadata: FGDC compliant for each layer.
- Vector Accuracy Standards:Vector data incorporated into the City’s GIS prior to 2002 is assumed to be accurate to within 10 ft. of real world location (rwl). Data incorporation processes in place since 2002 have ensured accuracies within 5 ft rwl. With the advent of the future digital submission policies, vector data accuracies will reflect survey grade expectations.
- Imagery Accuracy Standards:Satellite imagery is orthorectified in-house with RMSE < 2.0. Aerial photography spatial accuracy is sub-contracted and is within the limits offered by the individual contracted vendors.