#proceduralmodeling

Development Project 2 — Houdini PCG Study: Starting with Rebelway’s “Advanced Asset Creation in Houdini”

This development project started differently from my Blast Furnace. I didn’t begin with a concept sheet because the goal here was learning-based: I wanted to understand procedural thinking in Houdini and how PCG workflows could help me build environment assets faster and more flexibly.

To structure the learning, I followed parts of Rebelway’s Advanced Asset Creation in Houdini playlist. The course is designed for a much longer timeline than I had, so I treated it like a guided lab: I focused on the sections that taught me the core Houdini logic (fracturing → VDB → displacement → remesh), and I skipped anything that didn’t fit my timeline or immediate goals.

First Houdini setup and initial exploration of the node workflow.

First Houdini setup (what I actually built)

My first “proper” Houdini outcome in this project was a cliff wall / rock wall study. The point was not to perfect art direction, but to learn how Houdini lets you go from simple shapes → controlled chaos → organic detail, all procedurally.

“VDB workflow” (in simple terms)

In Houdini, a VDB workflow is basically:

mesh → “digital clay” volume → noise/detail → mesh again

It’s useful for rocks/cliffs/ground because the VDB stage blends pieces smoothly and lets you add organic surface detail without sculpting every part manually.

The standard VDB workflow I followed (corrected + continuous)

1) Start with closed geometry + generate forms (SOP stage)

I began with simple shapes (like a box) and created variation using fracture-style workflows (Voronoi-style chunks / stacked blocks). This gave me the “big shapes” first.

2) Convert geometry into an SDF VDB

Once the blocky forms were working, I converted them into a volume using VDB from Polygons. This is the moment the mesh becomes “digital clay.”

Key idea:

Fill Interior ON (so it’s solid, not a hollow shell)

voxel size / bands matter (too tight = displacement clips)

3) Give the volume “room” for displacement

Before pushing detail, the VDB needs enough band width (“space”) so noise can push the surface outward cleanly without cutting off.

4) Compute Gradient (the direction for displacement)

I used VDB Analysis → Gradient. Gradient behaves like volume “normals”: it tells Houdini which direction is “out” from the surface so displacement is controlled, not random.

5) Displace with noise in Volume VOP

Then I used a Volume VOP to push the surface along the gradient using noise. This is where the wall stops looking like fractured blocks and starts reading as rock.

6) Convert back to polygons + cleanup

Finally, I converted the VDB back into polygons using Convert VDB. This is the “return to mesh” stage, where I can adjust how much detail is kept using ISO/threshold-like controls, and then clean up any unwanted floating pieces if needed.

Convert VDB back to mesh (final polygon output stage).

What I learned from this first VDB study

VDB is basically Houdini’s “procedural sculpting mode”: it helps fractured pieces blend into one believable rock mass.

Gradient is the key: once I understood gradient = displacement direction, the workflow became repeatable.

The best results came from doing things in layers: big shape first → VDB unify → surface detail second.

References

Ev. 25

Ev. 24