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I recently got a paper copy of the as-built plan for my institution (a botanical garden), which I assume was produced using AutoCAD. I've got a bunch of graduate students coming for a week in a couple of months to produce a GIS representation of our site in ArcView, and rather than having them go out with a GPS to take coordinates of everything/hunt down topographic data etc, I'd like to just be able to convert the AutoCAD data into shapefiles.

Is that a reasonable plan of action? Is an AutoCAD map composed of separate layers that I get get from the surveyor, and then can be converted to shapefiles? (i.e the buildings are one layer, utilities another, boardwalks a third, etc). And, if so, since the map is to scale, would you just figure out the lat/long of one point in each "layer", decide on a projection, and every other point/feature would somehow get assigned correct geospatial data?

Also, any recommendations on converters from DWG -> SHP? Free-as-in-beer-and-as-in-I-don't-have-any-grant-money-for-this strongly preferred.

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4 Answers 4

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Expanding a bit on Marinheiro's answer: Even if the CAD data is georeferenced, there might still be some significant work to do to make it useable. I've often recieved CAD data that has georeferencing info in it, but the draftsman (or whoever produced it) simply ignored that and drew features all over the place. Then I have to manually align the features using the spatial adjustment tools (in ArcGIS). Granted that's a whole lot easier than starting from scratch, but it can be a pain.

If you're using ArcGIS, there are some CAD tools built into it. First, make sure the proper projection is applied to the CAD data using ArcCatalog or ArcToolbox. If you open the dwg and everything seems to line up properly, you can just right-click on the layer and save it as a shapefile. You can also use the "ArcToolbox > Conversion Tools > To Geodatabase > Cad to Geodatabase" tool to import your CAD data into a Geodatabase.

As far as the "Free-as-in-beer-and-as-in-I-don't-have-any-grant-money-for-this" route: If you don't have access to ESRI tools, QGIS has a plugin that will convert DXF to SHP, but I'm less familiar with that software than I am with ESRI.

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  • Hmm. Interesting. Wasn't quite complete on my $ situation - I'm applying for a grant from ESRI for free Arc* software, and from your reply it sounds like I might have a reason to ask for more than just ArcView. I'll post another question after I get out of a meeting, and would appreciate your advice.
    – Yewge
    Commented Oct 21, 2010 at 15:32
  • The functionality I mentioned above is all available with an ArcView license. I believe ArcEditor and/or Info have some additional CAD tools, but not sure.
    – Don Meltz
    Commented Oct 21, 2010 at 15:41
  • I was assuming that steve had access to arcgis. free software, I also think that qgis is the most practical one. but always take in advice what Mario Miller wrote too.
    – Marinheiro
    Commented Oct 21, 2010 at 15:55
  • I doubt many if any of my students have done more than play around with qgis. And I'm pretty sure I'll be able to score at least ArcView - this is exactly the type of project the grant appears to be set up to facilitate - but less sure I can get more than that.
    – Yewge
    Commented Oct 21, 2010 at 16:15
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All depends on your data. If your data is unstructured in dwg, then converting into shapefile will fail. For example, if you have polygons that are not polygons (closed polylines), but lines and polylines, then you will not be able to export them into polygons in shapefile. In that case you would have to create topology in AutoCAD Map which is out of the scope of this question. Next problem is with AutoCAD, to export data into shapefile, you need AutoCAD Map or AutoCAD Civil3D, not AutoCAD. Coordinate systems are also feature of AutoCAD Map/Civil3D, so for that you will need them also for this. In generally, you can do this in AutoCAD Map/Civil3D (i do it almost every day), but you'll have to got through some tutorials to accomplish all of this.

Because of this unstructured data in dwg, I don't think that there are any good dwg-to-shp converters out there.

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    true, true... this is something I almost never think. someone working with georeferenced data and that do not work properly. I know it's a mistake, but i expect a bit of quality from others.
    – Marinheiro
    Commented Oct 21, 2010 at 16:00
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if the data from your autocad file are georeferenced, when you convert from autocad to ArcMap, each layer results in a shape, and all the data in your shapes are automatically georeferenced

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  • That's what I was wanting to hear. Thx.
    – Yewge
    Commented Oct 21, 2010 at 10:56
  • what should I do if my autocad data is not georeferenced? I have troubles giving them a coordinate system and actually work. thanks.
    – Ligia
    Commented Jul 12, 2012 at 8:07
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I do this all day long. I would be happy to help georeference anything you can get in dwg format or even georefernce your scanned or plotted image.

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  • Got 30 students experiences
    – Yewge
    Commented Oct 21, 2010 at 16:07
  • ArcGIS,so presumably one of them will be able to do this, but thank for the kind offer. Although,I haven't met or talked with any of them, so maybe I'm wrong about their skillz and I might take you up on that after all.
    – Yewge
    Commented Oct 21, 2010 at 16:11
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    Weird. Dumb iPhone.
    – Yewge
    Commented Oct 21, 2010 at 16:12
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    sure, I ussually use autocad map to create (fast) and then convert to arcmap (ESRI). IF you would like to send copy of paper map it can be referenced and that would be something for them to start with in arcmap.
    – Brad Nesom
    Commented Oct 21, 2010 at 18:23

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