Thursday, May 8, 2014

Export Geometry from Navisworks into Revit (and back again) using only AutoCAD

I have previously discussed going from Navisworks to Revit using FBX - 3dsMax - SAT. However, maybe we can do this without 3dsMax. Did you know that vanilla AutoCAD has a FBXIMPORT command?

1) Export FBX from Navisworks - it will ignore Section clipping planes, but it will respect the Hide/Required setting of the view. You can limit polygons (advised for big models)


2) FBXIMPORT in AutoCAD - untick Cameras and Block options as they can be problematic.
Then save DWG. (Note - see below for correct 1:304.8 import scale)



3) Open Revit and Link in the DWG.
For this example, I used Origin to Origin as I wanted to try round-tripping back to Navisworks.

Once I exported the NWC and put it back into Revit, I noticed the file was out of scale. Now, I experimented with a few different scale settings, but everytime it was a scale of about 30 or 300 wrong. 1 foot = exactly 304.8 mm. Evidently, the "internal" units of an FBX are feet. So, when we import to AutoCAD we need to use this setting to translate to mm:

This time, when I exported the Revit view to a NWC, and then appended it back to Navisworks - it can came back in exactly the right place. This workflow relies on using the internal Revit Zero point and Origin to Origin linking.

There you go - now you can roundtrip any mesh geometry from Navisworks to AutoCAD to Revit and back to Navisworks :)

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