Georeferenced Autocad file in ArcMap

BrieeC

Hi, I was wondering if there was a way to georeference Autocad files in ArcMap/ArcGIS? More specifically, I want the Autocad file to align to a polygon that has a specific coordinate system. 

Or is there a way to have it georeferenced in Autocad so that when it is pulled into ArcMap/ArcGIS, it snaps to the polygon?

David_Brooks

You can georeference a CAD file in ArcGIS Pro and ArcMap, but the best practice is to do this in AutoCAD.

The benefit of doing it in CAD is that if you want to update the CAD information, it automatically reflects the change in GIS.

To do this,

1. make sure the units of your CAD session match the units of the GIS session (feet or metres)

2. find a snapping point in the GIS data that can be co-located in the CAD data (ie a vertex in a polyline/polygon or a specific point). > note down the coordinates of that location from GIS.

3. In AutoCAD, create a circle with a radius that is roughly 10 times smaller than the size of your CAD data (e.g. if it's a 1km square area of data, create a circle with a radius of 100m. This will make sense later). 

4. Select the circle, and update it's centre coordinates to match the coordinates you extracted from GIS (in the AutoCAD quick properties menu.

5. select all the CAD data in your model view in AutoCAD, then Ctrl+X your data.

6. navigate and centre on your circle you created

7. paste the data back into the area near the circle

8. reselect all your data (not including the circle) and type MOVE

9. when prompted, specify the base point as whatever the common vertex was that you had in your CAD data, then move all your data via this basepoint onto the centre point of your circle.

10. delete the circle and save your DWG.

Hey presto, the CAD data you drop into Arc will be georeferenced. Be sure to define the projection of the DWG in Catalog in case you seek to change coordinate systems etc.