<aside>

⚠️ Performance: Assume Uniform Radius is an optimization for large grain counts. For normal-sized sims, the difference is barely noticeable — so don't sacrifice varying @pscale just to save 0.0003 seconds, unless you're simulating half a beach.

</aside>

grains.mp4

SOP Base Geo

• Start with your base geometry.

SOP Points from Volume

• Create points.
• Enable Add pscale to give each point a radius.

SOP Attribute Randomize - or anything to create f@pscale variation

• Set to multiply
• Add variation

SOP Relax

• Set Relax in 3D Space.
• Relax by Scale so the spacing respects each grain's pscale.

(By default it will use @pscale)

SOP Vellum Configure Grain

• Default settings.

SOP Vellum Solver

• Advanced → Grains
• Disable Assume Uniform Radius ⚠️

Key idea

@pscale = individual grain radius.

If the grains have different radii, Assume Uniform Radius must be disabled.

Paint from Volume - Add Scale attribute to set pscale

Relax - Relax in 3D Space

Vellum Solver - Disable Asuume Uniform Radius