Cannot export OBJ or FBX meshes in V7

hi RMA team,

I went to export a SubD model from Rhino to keep working with it in Modo. The only way I know how to do this is _ExtractControlPolygon and export that as either OBJ or FBX. OBJ has been broken for a while and this week FBX broke too.

edit: running (7.0.20140.14505, 05/19/20)

Test cube file here:
My SubD object:


96 faces closed mesh:

3dm file here:
failing_export_mesh.3dm (296.4 KB)

I export to OBJ:

I get this mess in Modo (same mess in Fusion360):

single poly per cube face, and weird-ass normal map.

OBJ file here: (928 Bytes)
which BTW I had to zip up because discourse does not support OBJ :man_facepalming::man_facepalming::man_facepalming:

I know OBJ has been broken so I have not been using it, but it wasn’t this broken, now it seems like a rogue file export that no one is watching or something.

I’ve been using FBX instead, but today I found this weird message, in V7:

Can you please give these issues priority and be part of a weekly build Q&A test before releasing a weekly build? We need file imports-export to work to do our work.



Hi Gustavo- if you un-check ‘Create NGons’ in the OBJ settings, does the export do what you expect?


hi @pascal,

for that particular cube yeah the problem goes away, by introducing another problem, look what happens with the Ngons in my file:
I export this (right cube has Ngons)

I get this in Modo:

I proposed a new setting for all mesh exports:


@tim - do you think it is possible to have a ‘Preserve nGons’ as well as ‘Create nGons’ check box?

@gustojunk - does this item correctly address the export problem for nGons?
RH-58695 Export : OBJ - Allow preserving existing nGons


Also what about solving those weird normal maps generated from extract control polygon. We do want good/usable normal maps. We don’t understand why _ExtractControl polygon is grabbing the normal maps from the smooth SubD. Any reason/utility on that?

@gustojunk - I think you mean that the vertex normals are welded on the extracted control polygon, correct? Not having those welded seems not to affect SubD creation (from them) in Rhino - if it is OK downstream as well (Unweld, 0 degrees to test) I imagine that can be fixed - I do not know if there is any particular need to weld these.


Hi Gustavo - can you please close Rhino, and run a repair on the WIP inastallation via the Windows control panel > Programs? Does that sort anything out for fbx?


Thank fixed it! Thanks!

I checked, Unwelded is a problem, look what happens when I import the unwelded version in Modo and switch between faceted/SubD:

So it looks like if you guys can fix the ‘ngons sometimes’ problem and we uncheck normal map when we export OBJ things come in well for Modo:

…also the subD control cage option allows me to skip the extract control polygon, that’s nice!

I just wish we had a better Rhino<>Modo link. I need to explore some other options.



RH-58695 is fixed in the latest WIP