Optimizing render performance on VRayEnvironmentFog-heavy-scenes

[Art48]

Hi,

I have a scene which makes use of VRayEnvironmentFog. I got no texture in it, just plain fog with a pretty high distance and it looks fine as is (apart from much noise since I use thresh. 0.08 for my 800px preview renders which is fine).
Now I want to set up a 6k rendering and noticed that my sampleRate element is VERY heavy on the red side (with min2 max 30, 0,025)

What is with the new shading technique/no more subdivs with the recent .3 update?
I've never rendered Fog before and I wonder if it is normal to have a red samplerate pass with the fog enabled and how I would go about optimizing such a scene. Just throw more max subdivs at it? I'm testing around currently but I would love the render to be completed over the weekend and while I think that may be unrealistic I still think I could optimize. But where would I have to dial? Fog subdivs? MSR? etc?

ALso I use BF/LC for GI in a dark cave-like scene and I am aware that it takes a hit on rendertimes. AFAIK I can't use any other engine since I rely on reflective GI caustics and IR doesn't support it.

[svetlozar.draganov]

Would it be possible to attach a scene so we could see why it reaches the Maximum Subdivisions with such high Color Threshold value?
Is everything else looks expected if the Fog is disabled or the Sampler Render element is still mostly in red?

[Art48]

Sure, if you can give me an FTP adress I can upload it. THe render is completed now bot took a week on 1 machine (and 2 on weekends)^^

[Zdravko.Keremidchiev]

If you send us an e-mail to support we will provide you with FTP credentials.

[Art48]

Hi,

uploading right now "fog_scene.rar", gonna take a while though.

[svetlozar.draganov]

Thanks for the scene.

We have rendered the scene with and without the Environment Fog and the Sampler Rare render element in both cases was mostly in red, when the Fog is active the element is a bit more reddish of course but what I would like to point our is that the not only the Environment Fog contributes to high amount of samples fired in the scene.

Have you tried to render the scene with new default 3.3 settings? The settings that you using are quite high which ensures very long render times so our advice is to re-load the default settings and to increase them only if needed.

[Art48]

I'll try, we got a custom startup scene though, is there a way to quickly reset to actual defaults or do you have them written down somewhere?

[joconnell]

Switch your production render to the scanline and back to vray! Or open up a new scene, save a render preset with the default settings then go into your main scene and load just the bits you want.