Facets on mesh

[infographist]

Hello to all,

I am a junior imaging specialist, specialized in automotive design. My society is called RCD Except/Small Dots, and is located in the heart of the french automotive design, near Paris.
We decided to leave MR to use Vray (for Maya). This is a great rendering engine, but we have a recurrent problem, with interior automotive pictures, that does not appear with MR.

Let me show you two cases.



On this first example, I had to apply a bump on the material. But those facets appear. I thought it was because of my bump texture, but with a procedural texture (with a good repetition) it was the same. So I decided to do not apply bump just to see, but the facets were still here. So, I applied a vray subdiv on the mesh, but it did not really works and my rendering lapses time were long, too long. So I did not solve this problem.

Note that on this first image there is no bump



On this second example, it is the same problem. As you can see, there are facets on this mesh too. But here, the difference with the first example, is that when I disconnect the bump of my material, the facets disappear. It is present just when I connect the bump to my shader. Even though, I apply a bump procedural texture (so with a good repetition), the problem appears.

Note that on this second image there is a bump texture.

This problem is really recurrent, and does not appear with MR. We also tried with a more dense mesh, but the problem is still here. We tried to manipulate the normals of the mesh, but i didn't solve the problem.

So, we do not know what to do, and we want to stay on a vray worflow.

Someone has an idea ?

Thanks a lot for your attention.

Julien.

[Yannick]

Hi,
it might be worth checking the vertex normals of your geometry, they might be set to match the face normal. Also check you face normal are pointing outward. I am assuming your data is converted CAD data (with Autodesk Showcase?). We have this problem from time to time. if it is converted CAD data, maybe try to tesselate it again at a higher resolution.

Hope this helps.

Yannick

[infographist]

Hi Yannick,

Thanks for your answer.

The mesh come from CAD file (CatPart catia) and converted with Patchwork.

We have already checked all the normals, and what is unbelievable is that on the second example, the facets disappear when the bump map is off.
Anyway, I will check the normals one more time, but I think it won't work.

And we tried with a higher resolution mesh, but the problem is still here.

One thing, when I apply a simple materiel without any reflection, like a plaster or clay shader, there is no facets.

I really don't understand !

[ivaylo.ivanov]

Can you share some more information about your material and settings. If you can provide a stripped-down version of your scene we can find the problem easier.