Frustum VDBs in Karma

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Hi!

Will it be possible to support camera frustum VDBs in Karma? They are essential for water fx work when rendering whitewater, it'd be great to be able to render them.

Thanks!

Miguel
Edited by Megalis - Jan. 31, 2021 06:25:18
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I think this is a critical feature for Karma to have. It enables many great techniques to get high quality volumes rendered in a fast and efficient manner!
Edited by MattPuchala - Feb. 2, 2021 14:50:23
Matt Puchala
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I never thought to try this with karma. Are they currently broken? I haven't used frustum vdbs in a few years.
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Yes, right now trying to render one gives a black frame.

In our case, we always render whitewater as a frustum VDB, and many fire/smoke sims get rendered the same to do operations that push the detail and for the great speed up in rendering you can get, so it is a big feature needed if we want Karma to render fx elements.
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Just out of interest, 'camera frustum VDBs' Is this culling the VDB by the camera's frustum at render time, or something more complex?
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daviddeacon
Just out of interest, 'camera frustum VDBs' Is this culling the VDB by the camera's frustum at render time, or something more complex?

Not specifically, no. However, they will not contain anything outside the frustum by their nature. A frustum volume is a volume grid that is frustum-shaped, instead of box-shaped, and hence all the voxels are frustum shaped. This has the property where voxels closer to the camera are smaller than those far away, leading to the volume containing just the right amount of information for maximum detail.
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Does someone know how to use : "VDB Rasterize Frustum geometry node" ? What are differences with other vbd nodes ?
Thank you.
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