Reflection dim not working for deep reflection depths

[Micha]

Hi,

I have a scene where the two mirrors cause a lot interreflections. I hope to blend out the reflections by the dim function, but it doesn't work at the mirrored mirror.

For example if the distance is set to 700mm than the mirrored mirror is blend out. OK. Than I set 720mm and mirrored mirror is visible, because the mirrored mirror is within below the dim radius. OK. But the scene at the mirrored mirror shouldn't be visible, since ray should be much longer than 720mm.

-Micha

[Zahari.Ivanov]

Hello Micha

Would it be alright for you to share with us a sample scene like the one you described, so that we can investigate this behavior accurately with the same scene setup as yours? If that's alright with you, please use the V-Ray > Pack Project function and send it to our support email as an attachment or through a file-sharing service of your choice.

Thank you in advance!

[Micha]

Here an example with file. Two walls with a mirror. The distance between the walls is ~100 units. I miss that I adjust the dim distance and I can see like reflection levels are dimmed. My goal was to set a dim fall of so that at deeper level the reflection mute out. It doesn't work in CPU and GPU mode.
(My project scene was a little airplane lavatory.)

[Micha]

... I found that the dim falloff works for the first reflection level, but only in CPU mode (I have a lot GPU power, but not CPU.) So, two problems - dim distance over several reflection level (CPU/GPU) and dim fallof (GPU).

[konstantin_chaos]

So, two problems - dim distance over several reflection level (CPU/GPU) and dim fallof (GPU).

I can confirm that you've correctly identified both limitations.

A new feature request for the dim falloff on GPU has been logged a while back as VGPU-3568.

As for the dimming in secondary reflections - it might be possible but it might also look strange.
Keep in mind that the Dim Distance effect fades straight to the scene environment and might lead to very unnatural results.
Can you explain what exactly you're after?
There might be a different way to achieve it.

Konstantin

[Micha]

It's frustrating that GPU rendering doesn't support the same features like CPU. It would be great if both engines would allow to use all features at the same level. The limited dim functionality of the CPU mode would be better than nothing. Here a part of my project scene - all the reflection level cause a to complex look. Ideally I would like to see the first reflection level complete clear and deeper levels dimmed like by fog.

An other way would be to set an exit color and limit the reflection depth to 3 or 4. But it looks like the exit color options is gone. Is is missing at 3dsmax too?

[konstantin_chaos]

I would approach this as follows:
Add a reflection override material for the mirror - one which is less reflective:


The material that I've used is also attached:
Mtl_RecursiveMirror.zip

Konstantin

[Micha]

Cool workaround! Thank you.