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Garret Walter avatar image
Garret Walter asked

Houdini VDB fireball in C4DtoA

I've been feeling for awhile I'm doing some wrong when trying to render blackbody flames in C4DtoA. I've been working on a shot with 2 fireballs. I rendered out VDBs from Houdini but when I try and render in C4D the temperature VDBs seem to be way to high I end up getting these wayyyy to blown out values. Check out the attached images.

If I really lower the emission or intensity values I can end up getting the flames less blown out, but then I lose tons of details that I want to see. I've tried putting on a volume_sample_float to map my values better but it still seems to lose a ton of detail.

It seems like my temperature values are always super crushed in the very high end instead of being more evenly distributed and I'm struggling in finding a way to remap them.

I also included a second image that shows lowering the temperature significantly but also shows how much detail I end up losing.

Does anyone have any advice on how they set these up? Thanks.

c4dtoahoudinivolumetricsvdb
screen-shot-2018-08-28-at-105919-am.png (73.5 KiB)
screen-shot-2018-08-28-at-110316-am.png (143.7 KiB)
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Peter Horvath avatar image
Peter Horvath answered

Maybe it' something to do with scaling, I'm not sure. Does the render look correct if you render from Houdini with HtoA?

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Garret Walter avatar image
Garret Walter answered

I haven't tested it in HtoA, but I can get good results with Mantra. Interestingly it's almost entirely opposite compared to C4DtoA volume render. In Houdini I have to push the intensity quite a bit, in C4DtoA I have to turn the intensity down super low, to something like .001 in many cases to get anything even remotely similar.

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