V-ray Distributed Render - Normal maps/bump maps problem

[devailo]

Hello again. This time the problem we are wrestling is when we render a big scene using distributed rendering, Some buckets appear with slightly different colors. If one computer renders the whole image there are no problems, But wit DR the problem occurs. The buckets from different computers make the image appear slightly different and in an animation it looks like its boiling. Just a slightly different tint of the color and separated in the bucket squares. All the maps are on a server and its mapped in the same way on all computers. So its not a texture or HDRi problem. This only happens with the normal bump and we are using VrayNormalMap for bump. Any help would be greatly appreciated

We are using Vray 3.60.01, 3ds Max 2017 SP3. Some computers are on Windows 7 and some are on windows 10.

p.s. It happens mostly on VrayFastSSS2 but also on normal vray material.

[nikolay.kusht]

I cannot seem to repeoduce the issue on our side. Could you set up a simple test scene and send us to support@chaosgroup.com for further investigation.

[devailo]

Hello, well this happens mostly on heavier scenes, i will try to replicate it on a simpler scene but look at what i incidentally found and it is, i believe the same thing. In the V-ray Denoiser tutorial video https://www.youtube.com/watch?v=z-Vu5UcMuF4 at exactly 3:03 you can briefly see in the lighting pass the same different brightness buckets. I am attaching a print screen just to be easier.

In my case, the problem occurs in Shadows pass or reflections pass or lighting pass, mostly over geometry with normal bump added to it. As you can see its strongly apparent in one of these passes but in the beauty render its not visible. But in animation those slight slight differences are more apparent and it starts "boiling"

I dont know if you have acces to that tutorial scene, but i will try to supply a scene with the problem, in order to clear this mistake.

Also in the tutorial it is not distributed rendering, but still the different shaded buckets appear in the lighting pass. I am starting to wonder if it is a bug in V-ray.

[nikolay.kusht]

Thank you for the provided details. Although the issue from the tutorial video seems to look similar to your issue they might not be the same and we further look into it.

What kind of normal bump maps are you using?
Are you using Bercon maps in the bump slot as well?

[devailo]

Hello, we are not using bercon maps. We are using the vray normal map with a jpg or tiff or png for the main bump and another jpg or png for the additional bump. We tried all formats and different sizes, but the result was always the same. When we switch the map channel to 2 or 3, the render outcome is different and with some tweaks we can make it look close to the original but not the same. And the darker buckets disappear that way. This is our current solution.

Can you explain to me about this map channel ? i cant understand how it works and why

[devailo]

Hello, i am ashamed to say that the problem was that my computer had a newer version of v-ray compared to the other in the distributed render. Last month when my GPU died, the ITs re-installed my computer and all the software and a newer V-ray without telling us and thats why we missed it. So for now all is good.