Fireflies with Environment Fog

[mikecampau]

Just curious what settings or ways to solve getting really bad fireflies from area and point lights when using V-Ray Environment fog? I tried all different AA samples and light cache settings but with little improvement. Not sure if this is a known issue, or if I'm missing something?

[vladimir.nedev]

Are the fireflies close to the light source ?
Or everywhere in the fog ?

Greetings,
Vladimir Nedev

[mikecampau]

Close to the light source and falloff pretty quickly

[vladimir.nedev]

I think this is a known issue and there were some plans to implement importance sampling for this to help it clear the noise faster.

For point lights, you can change Falloff Type from Inverse Distance Squared to Inverse Distance to reduce the noise.
But of course this changes the light distribution and is not physically accurate.

Or you can brute force it by increasing the Max Subdivs in the Image Sampler until the fireflies/noise is gone.

Increasing Min Shading Rate will also help, but it depends on your scene as a whole, what other sources of sampling noise it has.
If there is a lot of DOF / motion blur, then increasing Min Shading Rate might lead to worse render times over the whole scene.

Greetings,
Vladimir Nedev

[mikecampau]

Thanks Vladimir... All good info. I tried a variation of all of the above and was able to make some minimal improvements, but nothing eliminated it all together. Hopefully it will be improved on the next release!

[vladimir.nedev]

If you are able to, please send me the whole scene or the relevant portion of it to my e-mail address.

Greetings,
Vladimir Nedev

[mikecampau]

I will have to try and recreate it at another time... project is NDA and I'm in a crunch to get it done. I'll circle back to this and send you something. Thanks!

[Hesekiel2517]

Hey there,

i just tried V-RAY Next for Modo and get fireflies when i use Environment fog and ies lights. As you can see Point lights are fine, arealights show little Fireflies and Photometric lights are bad. I tried your suggestions in this thread, but nothing worked. If i increase the max subdivs its getting even worse. The more it renders the more fireflies appear. Is there a way to get rid of these?

Thank you in advance

[Hesekiel2517]

I'm also under the impression that if an arealight (which is excluded from the fog) is in front of the camera the noise increases

[Hesekiel2517]