Importing CAD into radiance

Hi all,

I believe importing CAD to Radiance is an issue specifically for new Radiance users like me. Most of the topics discussed here are a bit old and many methods may not work anymore due to newer versions of applications.

My general question is: what’s your method to import CADs into radiance?

Also, I’m using Autocad2020, if someone can offer me a method in which I can import my CAD into radiance (geometry, materials …) it would be great.

Thanks in advance

This advice isn’t specific to Autocad, but .OBJ is generally the best interchange format for Radiance. If you can export to .OBJ, you can import to Radiance. You just need to make sure the material IDs or at least the group IDs are available in your transfer.

I recently added a utility to the CVS head called robjutil, which will show up in the next major release. This allows a number of handy manipulations directly on .OBJ, such as extracting and deleting object groups, coalescing vertices, removing degenerate and duplicate faces, and performing regular geometry transforms.

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Hi Amin,

the problem is probably the very poor export options in Autocad. I have
never used the recent versions, but according to the website, the only
non-propietary 3D-format supported by “export” are IGES and STL. IGES (a
high-level CAD) can be imported by other CAD software. There has been an
ongoing effort to remove open export formats, I remember the times when
you had OBJ, VRML & Co available.

You could use an open-source CAD, e.g. FreeCAD, to import your IGES,
mesh it, and export OBJ as understood by Radiance. You may also script
BRLCAD for it, if you want to set up a pipeline for frequent file
conversion. The STL files should also be easily read by e.g. Blender or
any decent modeller, and all these are able to write OBJ.

The general rule of thumb is that, once you get out of the propietary
fence, there is plenty of open source software for model conversion and

Best, Lars.

Hi! My experience has generally been a bad one… the most successful
attempts so far have been by using another software as a bridge.

In my case, I opened files on SketchUp (which works hard on reading some
non-SketchUp formats) and exported it with Groundhog.

Still, the import/export wasn’t perfect. I still had to fix tons of things.

Good luck!!!

Schorsch Mischler had written a tool “torad” based on Autolisp which worked pretty well for me some years ago for older Autocad versions:


Just my 2 cents. I had no problem importing 3d models into Radiance in OBJ format. But I did have issues with STL and PLY extentions. I tried OpenSCAD, TinkerCAD and free versions of AutoCAD. Nowadays I use Artec Studio + SOLIDWORK and try to avoid using any file formats other than OBJ.