topic Re: CAD to GIS without georefencing? in ArcGIS for AutoCAD Questions

CAD to GIS without georefencing?

NanciSarcinello — Thu, 21 Dec 2017 14:16:06 GMT

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!

Re: CAD to GIS without georefencing?

DanPatterson_Retired — Thu, 21 Dec 2017 14:56:30 GMT

see your duplicate post

https://community.esri.com/message/738055-re-cad-to-gis-without-georeferencing?commentID=738055#comment-738055

Re: CAD to GIS without georefencing?

TedKowal — Thu, 21 Dec 2017 17:17:43 GMT

How To: Define the projection for CAD data for use in ArcMap

Re: CAD to GIS without georefencing?

NanciSarcinello — Thu, 21 Dec 2017 19:32:43 GMT

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 <https://community.esri.com/?et=watches.email.thread>

Re: CAD to GIS without georefencing?
reply from Ted Kowal
<https://community.esri.com/people/tkowal?et=watches.email.thread> in *ArcGIS
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Re: CAD to GIS without georefencing?

DanPatterson_Retired — Thu, 21 Dec 2017 19:34:29 GMT

That would be the prudent decision.

Re: CAD to GIS without georefencing?

TedKowal — Fri, 22 Dec 2017 15:45:25 GMT

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).