Georeferencing an existing AutoCAD Map 3D drawing.

[mloper4LMDS]

What is the simplest way to georeference an exisitng dwg file in AutoCAD Map 3D so that it can then be exported to a GIS system for use by others who do not operate on AutoCAD?

[Pointdump]

Hi Marty,
Welcome to the Autodesk Forums.
"simplest way to georeference an exisitng dwg file"
Hard to say without seeing your drawing. If you know what coordinate system the drawing is supposed to represent, you can use command MAPCSASSIGN or MAPCSLIBRARY to assign a coordinate system. From there you can use MAPEXPORT to create a shapefile.
Dave

[ChicagoLooper]

@mloper4LMDS 

<<What is the simplest way to georeference an exisitng dwg file in AutoCAD Map 3D so that it can then be exported to a GIS system for use by others who do not operate on AutoCAD?>>

The SIMPLEST WAY is to perform a SAVEAS to dxf format (not dwg format). Then send the dxf file to another user. Be sure to tell the recipient that you don't know the coordinate system of the drawing. Actually, the correct term is you don't know the 'Projection' but you can, and should, provide the City and State (or specific street address) where the site is located. Or you may indicate the drawing doesn't have a projection at all because it's drawn in a random, non-geospatial location in modelspace.

With know how, the recipient can Re-project the linework to the correct location with an appropriate coordinate system using his/her own geospatial program. This means you don't have to worry about georeferencing the drawing because you have effectively transferred the responsibility of the geo-reference from yourself to another user. And there's nothing wrong with that. Really, there isn't.

Is this the best way? No, it's not. But make no mistake, it's definitely the simplest.

The best way would is to assign an appropriate coordinate system (MAPCSASSIGN) to the drawing, then use MAPEXPORT to export the linework to a geospatial format such as shapefile, Gdb, KMZ, or SDF, etc., etc. because those geospatial formats will make your linework plop down correctly in their modeling program. Yes, it'll work, provided you assign an appropriate coordinate system to the drawing beforehand. 

Warning: Only programs with geospatial capabilities will be able to plop the linework down in real-world coordinates at the real-world location. If a geospatial program is NOT used the drawing will open, but there's no guaranty it'll be consistent with other geospatial entities or geospatial imagery that's eventually added to the drawing.