Hey guys

I have seen a great video about making procedural rocks using Houdini VDB. I tried to do the same, but for me, Worley destroys the geo completely. The author says, he uses the volume sample node, I did also, and for a while, it kinda works, but it doesn't really give the result I'm looking for. I also tried another method, where I used surface (instead of fog) and in the VOP node I used bound parameters instead of the volume sample.

All in all, what's your VDB displacement method? I need a displaced surface, and I'd like to use VDB.

Anyway, I attached my scene, with the two solutions, and if anyone of you could take a look at it, and give me hint how to proceed, I'd really appreciate it

Cheers


Szabolcs

hello Szabolcs,
as you're noticed, modulating the SDF distance is different thing than displacement, if we are considering displacement as ‘pushing along normals’. In case of modulating the SDF distance, 3d procedural texture is shifting the zero threshold, used later for converting to polygons - however, texture is placed on volume, strong shift could create overlaps or some else strange thing.
Now if you want ‘pushing along normals’ this could be a VDB Reshape SOP with alpha mask, while texture has to be taken from something polygonal, to avoid volumic ‘overlaps’, like in attached file.
Anyway, once the plain pushing is enough, that is, you don't need cavities and such, it's a way faster (several times, probably) to do this on polygons, converted from VDB.

I'd like to achieve results similar to this:
https://vimeo.com/228238370 [vimeo.com]

And here the author says he uses SDF and also show his Volume VOP as well. The thing I want to avoid is the use of texture, and the issue present with polygonal objects around the corners.

szmatefy
I'd like to achieve results similar to this:
https://vimeo.com/228238370 [vimeo.com]

And here the author says he uses SDF and also show his Volume VOP as well. The thing I want to avoid is the use of texture, and the issue present with polygonal objects around the corners.

For his final ‘cliffs’ showed around 12.00 it seems he used polygons to ‘displaced edges’ phase, including that one. Something like scaled voronoi fracture, re-mesh and some noise over everything. A bit of noise is added to VDB at the end of the day, and imho exactly that phase is not looking very realistic, it's more like calcified mud ( Ok, technically this is stone as well).
Volume VOP I've noticed at 07.24, worley noise randomized by something and such trickery, seems to be more for basic formation, but not used for his cliffs.
All in all he got nice result, however, entire story is too much occasional, 90's style approach where certain popular method is looking like something in nature in certain case and it completely fails in another case, like specular shading pretending to be reflection. From something like Houdini I'd expect more ‘geologically plausible’ approach, let's say to start with constructive elements like calcification, erosion, abrasion, cracking…
Btw nothing wrong with Volume VOPs except they are slow as hell.