Extracting vector information from a .dwg file into a QGIS environment?

Question

I have a few CAD files in the .dwg format and I am trying to extract the data into a QGIS environment. The CAD files have a large number of different layers that represent different types of assets eg. water mains, underground electrical cables etc. These layers are mostly polylines, but there are a few point features and polygons.

I believe the .dwg files have a geo-reference (there is an annotation that displays a Point Marker Number, Easting, Northing and AHD numbers)

Is there a way to accurately convert the polyline, point and polygon features from the CAD file into QGIS?

Answer 1

You can try the plugin Another DXF Importer/Converter, or in QGIS 3 try the import DWG to geopackage function under Project in the menu bar.

Neither option will fully preserve everything exactly as CAD and GIS systems store information quite differently, but you will get to transfer over layer names, text, and colour information. Note that you may need to explode some blocks for them to transfer over properly.

If your original .dwg is already in the correct reference system (look at the actual coordinates for the features in your dwg, not just the annotations), it should appear in the correct geographical location when you import it into QGIS as long as you specify the correct CRS.

If the coordinates do not correspond to the right coordinate system, you can use the references in the dwg to align all the vector elements to the right coordinates, either using ALIGN in something like AutoCAD or a plugin like Vector Bender in QGIS.