Help with fireflies

[borisquezadaa]

Hi guys.
I was playing with CoronaVolumeMtl  and i'm getting a horde of fireflies.

Its a simple scene, no fancy stuff.

Check this out, as you can see the fireflies does not go away, instead keeps appearing (default settings even after 4000 passes).


Attached is the max scene and some renders at 20- 40- 80 passes so you better see. (Max 2014). If any want to take a look at it, most apreciated.

Maybe some bug?

(Corona A7.1-MAX 2014)
Greeting from Chile.

[maru]

I don't know what's the exact cause of this but it's probably related to the fact that volumetric effects are at very early stage of development. :)

[Ondra]

There are some precision issues in the scene, because there are very fine details, so some rays go through and cause the dots. You can somehow improve the situation by setting enviro distance (in devel/debug tab) to 0

[maru]

I tried with a default sphere and the same thing happened.

[PROH]

Hi. Found this "Firefly removal Max script" on the Iray dev blog http://blog.irayrender.com/post/91961451241/firefly-removal-max-script

According to a user on Maxunderground, it works with Vray as well. So I thought it might work with Corona to (haven't tried it myself).

I know it's not a "solution", but it if it works, it could maybe help anyway.

[borisquezadaa]

Awesome!... i can confirm that setting the enviro distance= 0 works like a charm!.

It renders pretty fast indeed and the fireflies are gone.

Also i can render a RealFlow .bin sequence with corona (using Frost) with no hassle! (So that known issue/restriction for Corona no longer exists).

Thank you very much!.

This is the effect i was after.

Out of curiosity, what that parameter (enviro distance by default 1000) does?.

[Ondra]

it limits they distance when computing ray scattering/emission/absorption for enviro rays. The problem in your scene is that either entering or exit face is missed for some rays, leading to the ray not exiting the medium before going into the environment - so the distance applies to it. If the parameter is high, a bright spot will be produced because you have volumetric emission set up