render artefacts - seeing wireframe?

[johnjoe]

Hi, has anyone had this happen to them and found a solution?

I'm using triplanar textures mapped to a vray shader an getting artefacts.

It looks almost like a normals issue however these are fine..!?

please see attached.

Massive thanks in advance,

Joe

[vlado]

Can you post that part of the mesh here or send it vraymaya@chaosgroup.com so that we can take a look?

Best regards,
Vlado

[johnjoe]

Hi Vlado, that's done.

Thanks so much,

Joe

[johnjoe]

Hi Vlado, any joy?

I think this has something to do with the bump..?

[max@mfx]

We are seeing this exact same error on the exact same application actually, a beige car inner ceiling!

Is there any solution to this?

We have seen this in a lot of cases before but have always been able to retouch or work around the issue. Now with animation it's a whole different matter...

Our geometry is flawless but as soon as a VRayMtl with a heavy bump comes on the wireframe becomes visible like above. Attached is a freshly created VRayMtl, the only modification is adding a bump texture. The same thing happens when using normal maps.



Max

[Morbid Angel]

that really shouldnt happen just curious your uv's are welded? alternativly have you tried different filtering on your bump texture?

[max@mfx]

Yep, they are welded, and I have tried every type of filtering possible. The problem is even there when using a procedural, so filtering isn't really the fault here.

I also tried creating a new small object matching it to a part of the original and snapped the vertices and UVs by hand, just to have nothing from the old object. Still the same.

I have also tried with and without all kinds of GI, using the DMC sample and the subdivision sampler. I have tried a lot!

Max

[Morbid Angel]

what vray build are you working with?

[Morbid Angel]

I was able to reproduce the issue. If you increase the shadow bias of your light (in my case dome light) it should solve your problem (worked for me anyway).

[max@mfx]

That actually works, at least for this particular type of faceting/wireframe defect. Thanks!

There are other types of faceting when it comes to glossy reflections + bump/normal mapping...

[Dariusz Makowski (Dadal)]

That is something I was bugging chaos a while back.

Basically if u have insaneally tiny bump and a sharp reflections. The bump will break the normal smoothness (in max/maya/MR/Vray as far as I tested) and u end up with faced square/triangle/ngomz ble reflections. Only sollution was to increase the bump tile size (make less tiles I guess)...

Let me know if there is any solution on that issue from chaos side...

[max@mfx]

Yep, it's definitely what you describe, but it doesn't really belong in this thread as it's another type of faceting than the thread author describes. I will keep researching the issue though!

[vlado]

Did you send us a scene for the wireframe issue already?

Best regards,
Vlado

[Morbid Angel]

Did you send us a scene for the wireframe issue already?

Best regards,
Vlado

Its easily reproducible. Create a vray mtl and apply it to a surface that has some curvature, add vray noise max tex to the bump make it really small and fine and crank the bump mul, create a dome light and render, you should see some wireframe appear in the curved areas.

[Dariusz Makowski (Dadal)]

It appears in reflections or in diffuse?

If reflections than that is known issue and happens across many platforms/renders...