Hi all.
OK, so I take a UVed multi-subdiv Zbrush model and export one of the lower levels, import into Max, then re-export without editing anything.
Now, if I import this new obj into Zbrush as a new tool then the UVs are fine, but if I import it back into the subdiv level of my original tool, it borks the UVs (they get flipped, but I don’t mean the whole UV space is flipped, I mean the indexes of each individual poly are flipped, so the UVs look OK until you apply a texture map or create a normal map and get what looks like facets, or re-export it and check it in another app and spot all the unwelded UVs). If I take my Max obj and check it in any other app the UVs seem to be just fine.
So now I try Maya instead of Max, and the problem disappears. So “yay”, I think, it’s an incompatibility between the Max obj exporter and the Zbrush importer, I can work around that.
Except that, if I export from Max, import into Maya (and confirm that the UVs are still fine at this stage), then re-export from Maya to Zb, the problem returns. So I can even use Maya to “clean” my obj in between Max and Zb.
So, to recap… there seems to be something in the Max obj format that Zbrush doesn’t like under one specific set of circumstances (but handles correctly under another), and whatever it is Maya can’t detect it but can somehow transmit it.
Any ideas? 