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I am working on a project to identify households within certain buffer areas of a proposed water pipeline. I have raster imagery of the area of interest, point data for the households, and a CAD drawing of the proposed pipeline and buffer areas. My understanding of what needs to be done is as follows:

  1. upload CAD .dwg to ArcGIS and georeference .dwg
  2. Digitize the pipeline
  3. add the raster image (for reference, mostly)
  4. add data of households
  5. add buffers
  6. select households by location

I'm stuck on step 1. Information about the CAD drawing:

  • The Coordinate System is unknown and the source can't provide the information
  • I do not have access to AutoCAD
  • There are features listed in the properties and visible in the data frame when loaded into ArcMap

I have tried every method out there to georeference the CAD drawing, including:

  • identifying a Coordinate Systems through the properties window based on known UTM
  • using Georeference tool to add control points - the issue here was that I couldn't get the projected raster image or the project point data to 'show up' to connect the control points from the drawing to the projected data
  • using the Measure tool to measure distance between what would be the control points and manually adding/subtracting the X and Y to manually move the drawing (this was the closest I came to a solution but it was a bad one)
  • converting the CAD features to shapefiles and trying to project those

Meanwhile, my dataframe properties and projected data were all on the same coordinate system.

  • If you are stuck on step 1 then there is probably no need to mention the future steps. I think it should be straightforward to georeference your CAD file against the raster image by following the documentation so I think you should try that again, starting with a blank map, and record the steps here up until where what you observe is not what you expect. – PolyGeo Jan 26 '17 at 7:26
  • As @PolyGeo mentioned, start with a blank map, then load the CAD file in ArcMap and look at the coordinate range. Do they look similar to what you see on your image and point data? Chances are the CAD file has the correct coordinates but doesn't include a CRS. – Techie_Gus Jan 26 '17 at 7:48
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In ArcMap, turn on imagery, zoom to where the CAD drawing should fit. Add the CAD dwg, turn on Georeferencing toolbar. Under it "Fit to Display" it should bring the dwg into the current view. Now pick a location on the dwg that you can see in the photo, Link from the dwg to the photo. Move to the opposite side of the dwg and again link from the dwg to the photo. DWG's only use 2 points. It should auto Adjust to a fairly close fit. Now export dwg to shapefile. Need a better fit you can use spatial adjust to "warp" or re-register it with more points. Now as a shapefile you can copy vectors from the shapefile into your editing layer. Copy/Paste is better than re-digitizing. That should get you started.

  • This was really helpful for step one, thank you! Now that my dwg file has been converted to a polyline that lines up with my raster imagine, I am having trouble getting that to be projected correctly with the point data. I even added a shapefile of the district boundaries and the point data, shapefile, and polyline are in 3 different locations, meanwhile the image won't show up in the display. Am I missing something really obvious here? – Marnie Jan 26 '17 at 19:45
  • Check the data frame/properties/coordinate system, it should have a projection defined. Next check each of the layers, properties, to make sure they each have a projection defined. If both the dataframe and layers have projections defined, they should all project on the fly to fit. – Bill Chappell Jan 26 '17 at 19:49

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