Pima County Department of Transportation

Geographic Information Services Division

Projections and Autodesk MapGuide Source Data

Projection requirements for data used with MapGuide Server vary for different types of data.

• SDF Files

  SDF files need to be in lat/lon without any projection applied. I.E. WGS84. Reprojection, if any, from the source data projection to lat/lon is done with the /COORDSYS parameter of the SDF Loader. Each MWF specifies a coordinate system that includes a projection and datum. SDF data is projected on-the-fly at display time. The MWF projection need not match that of the source data.

• SQL Data Source

  SQL Data Source layers are handled much like data from SDF files and need to be in lat/lon without any projection applied. I.E. WGS84. Reprojection, if any, from the source data projection to lat/lon must be done outside of MapGuide. Each MWF specifies a coordinate system that includes a projection and datum. Like SDF data, SQL Data Source data is projected on-the-fly at display time. The MWF projection need not match that of the source data.

  Note that this category also includes databases used for zoom goto.

  Databases that are created through on-screen digitizing with MapGuide create lat/lon files with the current map's projection. If the MWF specified coordinate system projection is changed, then the coordinate fields in the database need to be reprojected. One way to reproject the database coordinates is along these lines:

  • Add the database table to ArcView
  • Use the table as the source for an event theme in ArcView.
  • Convert to a shape file in ArcView
  • shapearc in ArcInfo to create a coverge.
  • Use ArcInfo project to reproject the coverage.
  • Use addxy in ArcInfo to make items with the reprojected coordinates.
  • Use ArcInfo arcshape to create a shape file that includes a database to replace the original database.
  • Delete any unwanted stump fields leftover from the coverage.

• Raster Imagery

  Raster Imagery files served by the MapGuide Server must be in the coordinate system and projection specified in the MWF properties. Imagery is not projected on-the-fly at display time.