Reflection Bumpmapping artifacts / clip off in highres renders.

[mdskay]

Hi together. I have a problem right at the moment, where i don't find a quick solution for, but maybe someone knows that issue or maybe its a bug, that is already fixed or not. Just need a idea from you pals, what that problem may come from.

I'm currently working on a print campaign render in 6k resolution and getting some strange artifacts in my reflection on a bumpmapped silverstrip and other regions. i have done all my test renders in 3k so the problem was never visible.

Here is a graphic with a cropped and downscaled region, to show up that issue.



I tried already decreasing all the cutoff values in different sections of vray settings and shaders. but nothing really changed. its always the same thing. It's also interesting that the artifacts are getting more dense and details when i scale up the bump texture to 200%.

I did'nt check yet the latest nightly version, if the issue still remain. At the moment I'm rendering with the release version of VRay 2.0

[2013/May/4|10:05:00] V-Ray: V-Ray for Maya version 2.20.01 from Feb 1 2012, 17:09:48
[2013/May/4|10:05:00] V-Ray: V-Ray core version is 2.00.01

Maybe someone knows that problem and can give me a hint who to get rid off it?
Anyway i will check one of the latest nightly versions.

Thx and Cheers,
Kay

[vlado]

Have you tried bicubic or biquadratic texture filtering (when you add the V-Ray texture filtering attributes to the File node)?

Best regards,
Vlado

[mdskay]

I tried it now. But the results are not really changing with bicubic or biquadratic texture filtering and smooth with mipmaps. the result are really changing a lot when i change the texture filter to SAT or Nearest. But the results both filters are not good for what i need or expect.

Still trying it on the VRay 2.0 Release Version.

[mdskay]

Ok! I think the problem is solved for now.

Looks like the reason for that previous results are the delta scale attribute in the bump section of the shader. I increase the value from default 1.0 to 2.5 and it smooth out the bumpmapping. I should say, its pretty much obviously, but never had something like that before...

here is the result. its better then before, thats for sure. for better quality i just need to scale up the texture res around 200% to smooth out the rest of the thiny bumps that are happen because of less pixel information right at the moment

Delta Scale 1.0 / Gaussian Texture Filter


Delta Scale 2.5 / Mipmap Texture Filter


but thx anyway for your help vlado.

Cheers,
Kay

[vlado]

Yes, that you have been my second guess, although ideally you should not have needed to change that. I would still like to take a look at that scene, if possible.

Best regards,
Vlado

[mdskay]

can't send you a pm. but i will come back to this in a few days. ok?

[Dariusz Makowski (Dadal)]

Jusging by your 1st post images this is normal in renderers. MR/Vray both has it everywhere I tested.

The moment u hit high res+very tiny and stong bump raytracers fail to get good bumping in reflections. I've posted it a while back and bugged people about it... its not something that is getting fixed as far as I can see... most visible issues where u can find them is car paints and bump based flakes etc etc...

At the end you just have to find that tiny line at which you can still render it without reflection issues.

Render the same thing in MR ull end up with similar results.

Not sure about second image.