Shading Normals

[john_barclay]

Hello. I'm trying to shade flat polys with very specific normal direction (in this example (0,1,0)). I was expecting the polys to shade consistently and I've used this technique before in Mantra and tested this with MaterialX in Karma. Sadly with Vray I'm finsding that there is variation in the shading across the different polys. Is there any explanation as to what might be causing this and/or a way to consistently shade surfaces with a user normal direcion?

SOPs point normals



Render with Karma


Vray render


V-Ray for Houdini number:22758 hash:ddb9fef from 19 Sep 2024 02:48
V-Ray Core 6.20.23 [e22648ee] from 12 Sep 2024

[bdancer]

> Is there any explanation as to what might be causing

From what I see V-Ray result matches your viewport screenshot - so viewport is also wrong?

[john_barclay]

>
From what I see V-Ray result matches your viewport screenshot - so viewport is also wrong?

Try to ignore the black backfacing sides, that is something else. What I'm referring to is that I was expecting the the lit (green) sides to shade with no variation. Karma shades with no variation, Vray has slight differences, which is not what I'm looking for. Looking at normals AOV you can tell tehy are not all the same.