Sketchfab Forum

Problem with PBR Light/normal/maps?

(Romainrevert) #1

Hello !

Mechanouille by romainrevert on Sketchfab

I have a problems with the PBR on the rear legs. The material is not the same as the front legs.
Everything look fine in Maya. Normals are ok, UVs too. Maybe I miss something.

I didn't found any solutions in other thread...
Thx for help ! :smile:

(Paul Sketch) #2

In editor, toggle "Double/Single Face", it should show that "back legs" seems to have different face orientation than the rest.

(Romainrevert) #3

Ok, I found a solution but it's strange. I flip the normals only on the rear legs. So, in Maya, the normals are in the wrong side but when I upload in Sketchfab, there back to the right side.

(Stephomi) #4

@romainrevert Ideally, you should just change the triangle ordering (flip triangle, change clock wise, etc..)
I don't know maya so I don't know how to do it.

Sometimes, mirror operators are the culprit when it comes to wrong normal/face consistency.


I don't know about Maya, but I've seen issues in Blender when using modifiers like Mirror.

(Shaderbytes) #6

@james , I cant recall the mirror "modifier" producing incorrect normals, my experience is the modifier is pretty robust.

Its when you use the mirror command (not modifier ) or scaling where you need to pay attention to whats happening.

In edit mode if you mirror or even scale by negative 1 via sort cut keys or menu options you need to flip the normals afterwards since they get inverted.

If these commands are performed in object mode it will appear fine as if not inverted because the scale is not uniform..but if/when the scale gets applied to the object the normals WILL then be inverted and you will have to flip them again.


@shaderbytes Ah ok thanks for clarification. This is me not knowing much about Blender :smile:

(Adeboye Grillo) #8

I've come across the same issue on 3ds Max.

When you use the mirror modifier or when you mirror objects in the view-port, the normals seem to have the right orientation while in 3ds max but it seems that at the moment it is being converted to fbx, the fbx miss-interprets the orientation by mirroring the orientation of normals along with the mirrored objects. This causes the bug on the Sketchfab viewer.

I experienced this with the 2010 version of the 3ds Max fbx converter. I've not noticed that bug on the 2014 version of 3ds Max and fbx converter that I've used in recent times.