Export vdb voxel size.

Started by xuanprada, May 01, 2019, 12:55:08 pm

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xuanprada

Hello,

Is there any way to control the voxel size for exported vdb clouds.
At the moment I'm increasing like crazy the voxel count, which gives me a reasonable quality in the vdb, but I realized that the voxel size is quite big and consequently I'm losing detail on my clouds. Is there any way to control this? Or is there any other approach to keep as much detail as possible in the exported vdbs?

I would like about the workflow that other people are using to export vdbs, specially for large surfaces
.

Thanks.

Matt

Hi, and welcome to the forum.

The size of the voxels depends on the size of the volume and the number of voxels. There isn't any other way to control this. In future we might add a feature to export subsections of the volume, or different sections at different resolutions.
Just because milk is white doesn't mean that clouds are made of milk.

xuanprada

Got it, thanks.
There are details that happen at render time that don't get exported as VDB no matter how much I increase the voxel resolution, right?
If so, is that some kind of procedural noise that I can re-create somehow in a 3D application? I'm already displacing the volumes with noises and that helps, but I'd like to get closer to what I can produce with Terragen.

Thanks!

Matt

You might be able to get good results by adding noise at render time in your application, but we don't do that so I don't really know what advice to give. Because of the resolution problem, our renderer simply doesn't use the voxel buffer at all for primary rays.

The voxel buffer is generated from the same procedural function that is used at render time. It is intended to be the best possible copy of what's rendered, at that resolution.
Just because milk is white doesn't mean that clouds are made of milk.

xuanprada

I see, thanks for the explanation.
I'm going to keep adding voxel resolution, even if I'm already adding a lot, there is plenty of room to add more, the vdb files are still quite small and render times are super fast.
Cheers.

paq

Hi Matt,

So to have a better preview of the real detail I will get with the .vdb export, can I rely on the <visualize voxels> option form optimization tab ? Or will the final VDB capture more detail than that ?
Gameloft

Matt

Quote from: paq on May 19, 2019, 01:02:18 am
So to have a better preview of the real detail I will get with the .vdb export, can I rely on the <visualize voxels> option form optimization tab ? Or will the final VDB capture more detail than that ?


They are fairly similar in terms of resolution. But the shape of the voxels may not be the same. The VDB voxels are axis-aligned whereas the Terragen render allows voxels to follow the curvature of the planet.
Just because milk is white doesn't mean that clouds are made of milk.

paq

Gameloft