CAD to GIS without georefencing?

Question

GIS and/or AutoCAD Users:

Is there any way to get a CAD drawing file to overlay a GIS basemap in the correct geographic location without having to georeference the CAD drawing? It seems that defining a spatial referenceffor the CAD drawing file does not do the trick. Does the person who created the CAD drawing have to assign a geographic coordinate system in AutoCAD? If so, what version of AutoCAD is needed to be able to do that?

Thanks for help!

TedKowal · Answer

In my experience either I geo-reference the CAD file (does not take long if you have enough control points), take a guess at the projections (trial and error -- this can be frustrating), or have the technician, if possible, use the correct projected seed file (I deal mainly with DGN's which uses a seed).

DanPatterson_Retired · Answer

That would be the prudent decision.

NanciSarcinello · Answer

Dan and Ted, I have tried creating a prj file for the cad drawing, converting from cad to geodatabase with the conversion tool, converting to shp file, etc, etc. and none of this works. A spatial reference is assigned to the dwg file, but it still does not appear in the correct location. I think this is because the dwg is still not georeferenced via control points. In order to create a world file, I have to create control points, but I want to avoid having to manually pick control points because it introduces inaccuracy, especially in areas where it not easy to see points/locations that correspond to the dwg and the GIS base map. I am thinking the only solution is to have the CAD technician assign the coordinate system when the drawing is created. GeoNet Re: CAD to GIS without georefencing? reply from Ted Kowal in *ArcGIS for AutoCAD* - View the full discussion