Importing CAD data
Posted by Mike Bienemann on 28-Jan-16 10:45 AM

DesignBuilder supports 2 types of CAD data import:

  • gbXML import for loading 3-D CAD models
  • 2-D DXF floor plan import

The rest of this page discusses the 2-D DXF floor plan import.

You can import 2-D DXF floor plan files created in AutoCAD or other CAD programs using the Files > Import > Import DXF data menu command. This starts the DXF Import Wizard which prompts you for the name of the file, the units of your DXF data and the attachment height. The DXF data can be moved around the model once it is imported, so you do not need to know the exact attachment height - you can import the DXF data at zero height and move it to the correct location using the Move command.

Note that DesignBuilder requires DXF data to be saved in R-11 format. Other DXF format may fail to load.

If you are having trouble importing the DXF data you should:

1) Check that you have specified the correct units. If the DXF data looks too small or too large you may have selected the wrong units.  DXF data itself does not have units so you may need to find out the units used in the source CAD model before attempting to import the DXF file.

2) Try 'cleaning up' the CAD data before exporting it to avoid paperspace, grids, fittings etc from being included in the DXF file.

See also Why do I get out of range errors when importing DXF floor plans

Once the DXF data is imported and correctly positioned you can use it to define the position of blocks and partitions. A typical process might go like this:

  1. Create new dsb site file
  2. Select location
  3. Import DXF data
  4. Draw blocks by snapping to the external perimeter corners of the DXF floor plan (requires 'DXF snap' to be switched on).
  5. Go to block level and draw partitions using the DXF partition data. You should take care to connect partitions to the external perimeters. A common mistake is to snap partitions to DXF data lying very close to the external perimeter but not close enough to create a connection with the external perimeter.  It is recommended that you switch of 'DXF snap' in the Drawing options panel when drawing partitions at block level to avoid this problem. Be sure to switch it back on again when you have finished drawing partitions.
  6. Import other DXF floor plans for other stories if necessary. Note that only one set of DXF data can be imported at a time. Once the CAD data has been imported into the model, the source DXF file is no longer needed by DesignBuilder and can be moved or deleted.

We have started work on a facility to import 3-D CAD data including the geometry of walls, windows, roofs etc using the standard gbXML data exchange format.  This option should be ready for version 2.

See also: 3D CAD Interoperability, IFC, gbXML etc