I tried to render a model imported from Maya. Before rendering, I want to make sure the normal directions are consistent. This is what I did: First, I added the point node and the facet node to the file node. Then, I used the point node to get rid of point normal and used the facet node to check the Orient Polygons. Thirdly, I attached a shader, which has a twosided node with default setting, to verify the consistency of the normal directions. I thought we could tell the normal directions were consistent if the model renderer had the same color, Sadly, the model was rendered out in different colors, which means, as I understand, the normal directions were inconsistent.

Pls see the attachment. I want to find out what is wrong. How exactly does the facet node work when “Orient Polygons” is checked?

Orient polys in the facet sop isn't 100% for complex meshes. I would just use an attribute sop after your file sop and delete any point normals and then turn on primitive normal display in the viewport. This will give you an idea of whether the prim normals are pointing in or out. If they are pointing in then add a reverse sop. If some are in and some are out then orient polys might help but very often you will still need to manually fix troublesome ones.

If the Maya model is good then they should all be consistent, either in or out and just need flipping or not.

Thank you very much for your suggestion. I want to know whether there is an attibute, the value of which can tell the direction of prim normals, namely pointing in or pointing out.
Many thanks!
:?: