Reflection and Lightcache problems.

[Robert]

I had a lot problems in reflection when using reflection on a 'single frame' bases. Hence in animations. So no store mode would work, also the camera path feature isn't working yet.
Anyhow I did wonder why there is so much flickering going on. The result was useless without a strong deflicker and denoising.
So I was testing what can be done and found why the result was so ugly. Beside the single frame mode, it was the 'Use for glossy rays' feature. Turning it off did the thing. Result was suddenly free of white spots and useful.
Downpoint are the render times, which doubled in some areas.
Now the question is, can't there be some further improvement to get render times back to be good? I mean double rendertimes do to some glossy reflections is hard.. Modo does that much faster and cleaner.

[Robert]

After further examing the Problem, it get quit clear that it is related to blend shaders, or alshader with multi roughness reflection. So if I just have one layer of reflection with no roughness it renders all well. But once I mix shaders V-Ray will always optimize the Lightcache in a fixed value of rougness. So lets say I have a GGX with 3% roughness, which is really subtile I get still tood results, but once I blend a 20% ward roughness with a clearcoat, V-Ray will optimize the Lightcache based on the max roughness, hence why it ruin the clearcoat result. So a possible bug could be that blend shader not get detected. In which case V-Ray should look at the lowest percentage Roughness not to the highest.
The effect on render time to my project when turning off the feature is about 20-30% higher rendertime. I'm not sure how much a further optimization would bring in the end, but I think this bug should be fixed anyway.

[vladimir.nedev]

Can you post a scene or part of it that shows the problem ? Or send it to my e-mail ?

Greetings,
Vladimir Nedev

[Robert]

Sure. Will do.