Hi Jamie,

> I noticed that the vn entries in the blender file are
> shorter six figures after the decimal MoIs have eight.
> I have no idea if and why that would make a difference.

No, that shouldn't make any perceptible difference.

The difference between those files has more to do with the way faces are organized with points shared between them.

The MoI example one is made up of several separate mesh pieces that physically touch each other but don't have "welded" points in common.

But they do have the same vertex normals where they are physically touching, that's why they should appear to be smooth with one another despite being in separate chunks.

If they don't appear to be smooth with one another, then it means that the stored vertex normals are not being used for the shading.

Every other renderer that reads vertex normals from the OBJ file will render that segmented cylinder as a totally smooth object without seams between the segments, but something seems to be different in how Octane is handling vertex normals that makes it appear different in Octane from other renderers.

- Michael