Exporting shapefile from CAD

[MilaReady__GISP]

I have a test shapefile (line data) that was exported from a CAD-based program called MineScape.  The file does not have a spatial reference, and I ran the Define Projection tool under Data Management.  However, although the shapefile properties now indicate that it has been changed to NAD 1983 UTM Zone 12N, the shapefile does not display anywhere near the actual location.  I also tested the Project tool, and had the "Inconsistent Extent" error.

Does anyone have any thoughts on steps I may have missed?  Also, are there tricks for exporting CAD data (either as .dwg, .dxf, or .shp) with a spatial reference that I can pass on to the engineer?  Thank you very much.

[ZacharyAubrecht]

This seems to be a pretty universal problem. My point shape files have lat/long values in the billions no matter what program I define the spatial reference in. I hope this thread gets answered.

[MelitaKennedy]

A few things to check:

What are the units of the CAD data? Sometimes the units are scaled to use centimeters or some fraction of an foot (or inch). If that doesn't match what the coordinate system is using, the data won't be in the correct location.

Also ask the engineer if the CAD data is using grid or ground coordinates. To successfully use one of the predefined coordinate systems in ArcGIS, it must be using grid coordinates. Ground coordinates are scaled. It's usually possible to define a custom system to take that into account.

Is the CAD data really using the coordinate system that you think it is? Many surveying projects use a 'local' coordinate system with an origin in the project area, some angle to north, etc. It can be more difficult to figure out a custom coordinate system in this case.

Sometimes you have to use the georeferencing toolbar to get the CAD data to align with reference data (at which point the CAD data is using the same coordinate system as the reference data.

Melita

[PhilipMorrison]

I have a test shapefile (line data) that was exported from a CAD-based program called MineScape.  The file does not have a spatial reference, and I ran the Define Projection tool under Data Management.  However, although the shapefile properties now indicate that it has been changed to NAD 1983 UTM Zone 12N, the shapefile does not display anywhere near the actual location.  I also tested the Project tool, and had the "Inconsistent Extent" error.

Does anyone have any thoughts on steps I may have missed?  Also, are there tricks for exporting CAD data (either as .dwg, .dxf, or .shp) with a spatial reference that I can pass on to the engineer?  Thank you very much.

I was never able to get that to work either.  However, I was able to import the DWG file itself into ArcMap.  You first have to define the projection.  Make sure you define the projection to what it was drawn in, not the projection of your map (it took me a couple of tries before I realized that.  Duh!!).  For example, our engineers use the state plane system.  I also discovered that I need to have the DWG file saved in an earlier version of AutoCAD.  I am using ArcMAP 9.3 and it doesn't seem to be able to convert the more recent versions of AutoCAD, so I have the engineer save me a copy in the 2004 format.  After it is projected, I just add it to the map.  Then I export the various layers that I need to individual shapefiles and add them to the map.

I don't know if this is the best way to do this, or if it will work for you, but it works for me (so far!).