Artifacts in VrayEnvironmentFog

[elivnA]

Hello,

I'm rendering an interior with 3dsmax 2016 SP4 and V-ray 3.50.03. I want to use Environmentfog to get some volumetric sunlight, so I made an all black Vray material and put that in the MtlOverride slot so I can add the volumetric light in post.

Lighting is done with an HDRI inside a Domelight. Mostly default settings. On the image there are black artifacts visible. Is this a known bug? Or am I doing something wrong? They show up in both progressive and bucket mode. I'm not rendering distributed. LC/BF, with everything set to defaults except the dyn. memory setting (set to 0).

[matanov]

Hi,

Try without Adaptive lights.

[vlado]

Before that though, try updating to 3.50.04 and see if it helps.

Another solution is to assign a VRayColor texture to the "fog color" slot of the VRayEnvironmentFog (it will also render cleaner).

Best regards,
Vlado

[LudvikKoutny]

Before that though, try updating to 3.50.04 and see if it helps.

Another solution is to assign a VRayColor texture to the "fog color" slot of the VRayEnvironmentFog (it will also render cleaner).

Best regards,
Vlado

This sounded very interesting, so I proceeded to try it, to see if it renders any faster, but it actually makes the environment fog render ultra-slow in my case :O

[vlado]

Increase the step size to make it faster.

In any case there will be a fix for this soon.

Best regards,
Vlado

[Macker]

Another solution is to assign a VRayColor texture to the "fog color" slot of the VRayEnvironmentFog (it will also render cleaner).

Out of curiosity more than anything, why is this the case?

[elivnA]

Thank you for your time guys! Would like to report back that turning to Full lights evaluation fixed the issue. Inserting a VrayColour map in the fog colour slot did not do anything. I will try to see if updating to 3.50.04 will fix it later on.

[vlado]

Out of curiosity more than anything, why is this the case?

It changes the way the fog is sampled when there is a texture map.

Best regards,
Vlado

[vlado]

Ok then. Just FYI, the issue is actually in the environment fog and I hope to have a fix for it soon.

Best regards,
Vlado

[LudvikKoutny]

I ran some more tests in the meanwhile, but still no luck. Stochastic sampling is still a lot faster than VrayColor raymarching. I tried even extreme step size values like 500cm, and both raising and lowering subdivs and texture samples, but no combination was even close to how fast it renders without VrayColor.

Now when I consider that in vast majority of my scenes, EnvironmentFog with stochastic sampling renders about twice as slow as ScatterVolume material, then there's definitely room for improvement

[vlado]

Ok, good to know - thanks for the feedback!

Best regards,
Vlado