Popping in - I have to read all this more carefully.

But just quickly, the Maya cylinder normals were not the average of all the adjacent faces. Only when I imported in Blender did it look that way.

In the Maya cylinder, each vertex had two different normals. The average of two side faces was used for a side face normal (basically pointing straight out along the radius). But the same vertex was specified as [0, 1, 0] (straight up) when using it in the cap.

If you think about it, that's reality, right? If you're going to use a single vertex to represent the corner of a pair of adjacent side quads, that doesn't have any Y component - it is horizontal. Whereas, the same point on the upper cap should be [0, 1, 0] all the way out to the edge.

In this type of model, we're asking the render to just ignore the common point. It's not REALLY the same point. In reality, it is impossible for the same point on a cylinder to simultaneously have a VN pointing up and a VN pointing out. But that's what is recorded in the file.

I don't think there is a legit way to interpret that.

In any case, if you don't have VN data in your OBJ at all, then there can be no VN contradictions., Then Poser will calculate the exact same normals, based on crease angle. That's why deleting the VN data works (I think) for the Maya cylinder.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)