How to Convert CAD Files and Propagation Model Output into GIS Formats using QGIS

This article describes how to use QGIS to convert CAD Files (DWG/DXF) into four GIS spatial formats: Shapefile, GDB, GeoJSON, and GeoPackage.  It also describes how to convert propagation model raster output into a vector format.

 

CAD to Shapefile 

 

Note: Plugins can be installed directly from the QGIS Plugin Manager within the QGIS application. 

  1. First convert the DWF/DXF file into a GeoPackage format using the CAD to GeoPackage instructions below.  The GeoPackage will contain the layer or layers needed. 
  2. The layers created within the GeoPackage can be extracted and used as shapefiles. 
  3. Run the QPackage Plugin. 
  4. Select the desired layers within the Geopackage. 
  5. Export them as shapefiles.

CAD to GDB 

 

Note: You must have installed QGIS through the OSGeo4W installer and have “OGR FileGDB Driver” checked within the “Libs” menu. 

 

Note: Natively, a GDB cannot be edited in QGIS, as it will be read-only. The user must install the GDAL Vector driver FileGDB, which provides read and write access to vector layers of File Geodatabases (.gdb directories) created by ArcGIS 10 and above. 

  1. First convert the DWF/DXF file into a GeoPackage format using the CAD to GeoPackage instructions below. 
  2. Once the Geopackage is created, extract the layers. 
  3. Add the layers to the display and right-click the layer in the Layers panel, Select “Export”select “Save Features As...” 
  4. A window will appear where the format can be chosen.  Choose ESRI FileGDB. 
  5. Browse where the output file will be saved. 
  6. Select the desired feature dataset. 
  7. Click Ok, and the new GDB file should appear in the display. 
     
CAD to GeoJSON 
  1. First convert the DWF/DXF file into a GeoPackage format using the CAD to GeoPackage instructions below. 
  2. Extract the desired layers from the newly created GeoPackage. 
  3. Ensure that the coordinate reference system is correct. 
  4. Right click the shapefile in the Table of Contents and select Save As. 
  5. Browse the options and select the format as GeoJSON. 
  6. Select the CRS button and select the appropriate projected coordinate system. 
  7. Click Ok, and a single GeoJSON file should be generated. 

CAD to GeoPackage 

 

Note: A single GeoPackage file can contain various data types (both vector and raster) in different coordinate reference systems, as well as tables without spatial information. 

  1. Open QGIS and select Project → DWG/DXF Import Tool. 
  2. Within the dialogue, specify the location of where the GeoPackage will be located. 
  3. Specify what coordinate system used by the data. 
  4. Select the source drawing (the DWG file that is being imported). 
  5. Choose with attributes to carry over into the GeoPackage. 
  6. Click Ok, and the drawing should appear on the display as a collection of layers in the table of contents. 

Propagation Model Output  

 

Propagation modeling software may produce data in different formats. Here we describe how to convert raster output from the software into a vector format using ArcMap.  The BDC system accepts four vector GIS formats: Shapefile, GDB, GeoPackage, and GeoJSON.  

 

Note: For BDC, the raster data output from the propagation model software must be 100m resolution or finer.  The maximum size of the raster bins is 100m by 100m.  

  1. Open QGIS and locate the Raster Pixels to Polygons tool. 
  2. When the tool dialog window appears, select the raster layer, band number, field name, and the output vector file. 
  3. Click Run, and the vector layer output will be created. 

 

For more information, see the QGIS User Guide at https://docs.qgis.org/3.16/en/docs/user_manual/ 

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