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How to multiple falloff FOG masks in VDB?

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Andr
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I want to scatter in space a bunch of spheres, each one being a different FOG volume with a falloff density.
I want then use them all together as single mask in a “VDB reshape” node.

I tried 3 different ways, from left to right:
1) It works but it's much inefficient: too many points.
2)It works but it's SUPER inefficient. Too many volumes are being created.
3) Another approach, it doesn't work but I can already see it would be SUPER inefficient. Again, too many volumes.

Please have a look at the project file!

I guess there's very simple way I'm completely missing :p


Thanks!
Edited by Andr - Aug. 10, 2018 17:55:54

Attachments:
Q_multipleFallofMasks.hiplc (169.2 KB)

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jsmack
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I think you will find the volume rasterize tools useful. I have attached your scene modified with some examples.

Attachments:
Q_multipleFallofMasks_edit.zip (36.7 KB)

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Andr
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Hey jsmack, thanks a lot for the effort you put into it!
Very very helpful and I got to learn few more nodes (-:

cheers
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Andr
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ps. I'm using the mask for a ‘VDB smooth’ node and I'm noticing that the whole Geo is getting a really small amount of blurriness outside the mask (even outside the bound of the FOG vdb used as mask, which don't cover the whole Geo, as shown in the picture).
This very little overall smoothing is not a big deal, but I'm curious to know why it's happening outside the mask.

Any idea? (-:

I attached a simple project file that shows this small issue.
Edited by Andr - Aug. 12, 2018 15:24:37

Attachments:
referenceWireframe.JPG (93.7 KB)
Q_smoothMaskEverything.rar (434.7 KB)

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tamte
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it seems to be doing it even when you plug in completely empty mask VDB volume, seems like a bug or maybe some limitation
Tomas Slancik
FX Supervisor
Method Studios, NY
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Andr
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ok, thanks for checking it. I've sent an email to SESI support, will report back here
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Andr
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A Houdini developer clarifies:

“The SDF smoothing tools rebuild the SDF. This always adds some smoothing everywhere, not just at the boundaries.”
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