xiaolin liu

JordanWalsh
So I'm back on this issue after a while!!
So how can I bring in the sdf and densities of the volume to sample in the shader in the same way as a volume sample from file node?

Render that vdb directly,and volume sample from file in shaders (surface shader and light shader and/or disp shader), i think.

fxrod
Hi Xiaolin:
Also, vdb does not use an octree structure. :wink:

Ah, i thought it was a impl of sparse voxel octree. can you tell what acc structure it actually used?BVH?
Also,i think might this case vex v proc always faster than vdb.
and flexible use micropoly engine to get the same blurry effect.

fxrod
Hi Guys:

I've been mulling over the pros & cons of using vdb vs cvex vol procedural for rendering a field of thin mist in mantra pbr. Although sparse volumes are very fast to generate, I wonder if a cvex/vol procedural setup would yield better detail, since the noise is sampled at rendertime and is only limited by step size. Also, does anyone know if rendertimes are faster with a procedural?

Thanks in advance!

In your case
VDB = cached volume procedural.
in general VDB = calc once,vex volume proc = calc every frame,so vdb must faster than vex a lot?
These two use both octree accelerating structure.
Vex volume procedural's parm “Octree” need about 256 in my experience,a 2k pic can takes only 1min(Vex v proc) in my experience.
But VDB slower than vex v proc in the same detail. i think maybe that is bcz the contents you rendered are not continuous. :roll: