tried to export a USD mesh from Solaris to Zbrush and you can see in the images below the results that I got. I tried changing the normal, I tried different subdivision algorithms but neither of those worked. Any idea what's the difference in the way these applications are handling the meshes? this also happened when I exported USD from Solaris to substance painter, but once I add a subdivision attribute to the mesh it works as expected so I'm really not sure what the issue is.

When you say "I tried changing the normals" do you mean you reversed the winding order of the mesh (reverse sop), or just flipped the direction of "N" (normal sop).

Houdini orientation is leftHanded and it might be that zbrush is assuming rightHanded and ignoring the left handed orientation that lops/sops typically authors onto gprims. If that's the case I would expect reversing the winding order to work, but not reversing the normals.

Subdivision shouldn't be influencing the orientation at all afaik.

antc
When you say "I tried changing the normals" do you mean you reversed the winding order of the mesh (reverse sop), or just flipped the direction of "N" (normal sop).

Houdini orientation is leftHanded and it might be that zbrush is assuming rightHanded and ignoring the left handed orientation that lops/sops typically authors onto gprims. If that's the case I would expect reversing the winding order to work, but not reversing the normals.

Subdivision shouldn't be influencing the orientation at all afaik.

Yes, your suggestion worked! No idea why adding the subdiv schema solved the problem in painter. But reversing the winding order does work for both zbrush and painter.

traileverse
No idea why adding the subdiv schema solved the problem in painter.

Maybe the subdivision code path in painter made the surface double sided for some reason. It’s fairly common for there to be bugs handling orientation, sides, normals etc in these applications when dealing with edge cases (like Houdini being left handed, and USD defaulting to single sided when many apps assume double sided as the default).