People complain about the fact that FBX files exported by Revit are too large.
The size of the FBX files exported by Revit is influenced by the following aspects:
Model size:
Obviously, the more details in your 3D view, the larger it will be. There is not much you can do about it besides controlling the way your families are drawn (fine, medium, coarse display settings).
Texture Maps used by the Render Appearances:
All textures used by the Revit materials are embedded in the exported FBX for portability reasons. On one hand, this is useful because you don’t have to bother about file paths issues (“texture not found” errors) but it has a cost in terms of file size. If you don’t render in Revit, you might want to think about editing your materials in a way that textures are not used at all. This way, the exported FBX file will not contain additionnal image files.
Environment Maps:
Revit defaults to a rendering setting that uses a texture map for clouds. This texture map on itself weights about 20Mb and cannot be compressed more. Since it is also zipped up with the exported FBX models, you take a 20Mb hit right away. To resolve this issue, switch the render settings of Revit to use a clear sky (no clouds). Doing so will remove the large clouds image file and reduce the size of the exported FBX file.
