Loading Files with Unknown Projection

Global Mapper loads many data formats that do not have projection information included in the file format.

If there is a .prj , world file or .gcp file with the same file name in the same folder, that information will be used to spatially locate the data.

Image or raster layers that are loaded with no spatial reference information will provide a dialog of option for loading the image. See Loading Rasters/ Images with No Spatial Reference Information. Image formats that are geospatial, that are missing reference information may prompt a dialog to specify the projection information.

Vector data formats contain coordinate values in the stored geometry, so if the projection is unknown, there will be a prompt to specify the projection. Note that vector data can be shifted or rectified after the coordinate system is interpreted, and a .gcp file of the same name in the same folder as the vector data will apply additional transformation to the data.

For more information on 3D model projections see Loading 3D Model formats

The suggested projection for the layer uses the following logic, including a check to see if the unit values are of an appropriate range:

Projection of other files loaded in the workspace from the same folder
Last projection user selected on a projection dialog in this session
Current view projection
Projection from default.prj in global_mapper.exe path
*Projection from default.prj in User Data Folder path
Last projection user selected on a projection dialog in previous session of GM
Default UTM/15N/NAD83 projection

*To customize the default projection, add a default.prj file specifying a projection to the User Data Folder.