Multiple Fume Boxes- render artifacts (FumeFX 3.5.2)

[rconover]

I used to use multiple fume boxes with max and windows (scanline and v-ray) all the time with no issue.
The issue seems to be Maya (and Linux) and mental ray.
I get random-certain frames-but not all 'tile-like' squares or 'squares with noise'
when the render camera has to render two (or more) fume boxes at once. They do not have to physically overlap-or visually either; on the frames it happens i can orbit around with the perspective camera and see a variation of the bug from all angles. But if i hide the multiples till one box remains-it renders as expected.

-the sim is fine-I can get correct sequence renders one-box-at-a-time.
-not shadow or light map related
-happens w/without Maya Volume Sampling
-alpha is effected as well.
-the artifact occurs with visible fume boxes whose simulation begins many frames later as well. If the box/grid is visible 'at all' it seems to be enough for the bug.

This feels like the classic (I saw this with Softimage in the '90s and multiple volume lights) mental ray multiple volume render bug. Pretty well known/documented issue for mr I believe. Its just that this one renders 'most frames in a sequence' fine. But the ones that don't render correctly-never will. Its like it 'almost works'-but isn't quite there.

Is this known?

Like i said i do this often and it will get tedious (rendering as many passes) to render with say arrays of fume boxes; for example a row of guns all firing together as a volley.

[sitnisati]

Hello,

Could you please post a scene so we can check your mental ray settings?
In scenes with multiple grids, AutoVolume is a must.

Regards,

Kresimir Tkalcec

[rconover]

Yes I tried that and was hopeful. But when (on the frames) the issue is apparent 'Autovolume' just seems
to make the artifact more visible/larger. No real improvement with sampling set 1 or 200 (max of slider).
Meanwhile unchecked Autovolume returns the artifact back to what it was. Unexpected?

I've made a scene-but have to wait till next week to get it approved for sending. The random nature of the bug
today has it only visible from the perspective window on the frame I expect the issue. But I can still repro.

[sitnisati]

Hello,

Can you maybe make some simple/small scene so we can repro ?
Maybe if you keep lights, camera and FumeFX grid and use only Simple Source the effect would still be visible?

Regards,
Kresimir Tkalcec

[rconover]

I was able to make one from scratch (attached). You'll need to make a local version of the cache for
'fumeFX1'. Then get the boxes 'fumeFX2' and 'fumeFX3' to use the same result cache.
I rendered via the perspective camera and could see the issue via the UI renderview and with render batch.

[rconover]

From here it doesn't look like the attachment worked.
Not sure how to do it (so it works). No error.

EDIT .zip files are the answer.

[sitnisati]

Hello,

That you for the sample scene.
I was able to reproduce few white alpha channel pixels artifacts, but if I increase sampling level to 1 or more, the problem is gone.
Can you please post an image so I can see exactly what to look for ?

Please let me know if sampling level fixes the issue on your side.

Regards,

Kresimir Tkalcec

[rconover]

Typing all this again. I did an edit that seems to fry the reply.
Seems to be 'more repro' with render batch.
But try frame '7'. Better yet render all 19 frames with render batch.

Here is my frame 14 (attached) The rightmost fume box is 97% obscured by 'black tiles'.

For me Render Settings>Features>Volume Samples and/or Auto Volume (checked) only seems to increase the amount of 'black tile'.

[sitnisati]

Hello,

It renders fine on Windows and Linus here with the upcoming FumeFX 3.5.3. We were fixing few shader issues for this update and it seems we've fixed this as well.

FumeFX 3.5.3 should be available by the end of the month.

Thank you.

Kresimir Tkalcec

[rconover]

Fingers crossed.
I'll test it again with that drop.