indirect lighting on ffx smoke

[bdemetz]

Is this supported? I'm looking for any way to get it working: light tracer, final gather, gi, final render, vray, however.

Thx a ton,

[Rif]

officially its not ..When tested , except the fact that your not getting hdr pixel distribution in color bleeding , the Ambiant coloring was much faster and was giving similar results.. that would be a work around atm ..

[bdemetz]

Hi Rif,

Sorry I don't quite follow the workaround you describe. I'm just trying to avoid creating a dome of lights to simulate a skylight in mR. So you're saying just raise the ambient color?

[Rif]

yes let say you have a redish "Oblivion Gate" like Environment Skylight or Phisical Sky in Fr .. Put the Ambiant a bit Redish toward skyish average color and you will get the coloration that , back in the days when tested , seemed to be fairly similar to indirect light bleeding on the smoke ..

[bdemetz]

Ah, I see what you're saying. I think what I'm really after is indirect ambient occluding 'shadows' from the smoke onto itself. A similar look if I put up 50 lights on a sky dome - Just want to avoid the shadow calculation time.

[Rif]

yes .. the shadows are indeed an issue.. it was my number 1 argument when trying to push it through ! .. i hope in the futur this will get back in testing..

[bdemetz]

Maybe a future FFX enhancement, if no skylight feature can be implemented, could be to add a setting to allow for soft/innaccurate shadows, so we could toss up a simple dome of a few shadow casting lights that wouldn't take too long to render. Even further, separate shadow softness control for each light would be awesome!

Another idea would be something I once did using Afterburn - I created a separate pass where I used white matte spheres locked to each particle where an Aburn puff was and did an AO pass, blurred it, then multiplied it over the smoke, didn't look half bad. Maybe something like that, but from within FFX - so the equivalent would be that FFX computes a rough/soft estimate of the voxels at low quality - maybe even skipping voxels (like a viewport preview), does some type of skylight shadow casting routine, and then multiplies that with the primary render pass.

Just a few thoughts. There's probably more gruvee ideas out there.

[bdemetz]

For now, an efficient method i've been using to fill in unshadowed areas of smoke with light is to go to each light and drop the shadow density from 1.0 down to .9 or so. Works so so - a decent work-around for now.

[sitnisati]

Brian,

Some hack could be done, but I think we will have to do it correctly for a production quality - which means multiple samples for each voxel. This can be optimized, of course, but it would still be very slow compared to polygon GI.

Kresimir

[jrand]

maybe a silly idea, but it would be cool if you could drop an environment map in the smoke>ambient color slot, you could then maybe fake it.

[bdemetz]

hacks, production quality - i'm game. thx for the information. i look forward and welcome any enhancements of course - but don't let me hold up being able to retime a sim

i'll have to try that idea of an 'env map for the ambient color' idea for adding varying color around the volume. thx for the tip.