Primvaria

Physics-ready variability for Physical AI, in OpenUSD.

Primvaria is a suite of procedural asset generators for the objects robots struggle with most: grains, cloth, cables and small mechanical parts. Every generator follows the same approach: distributions instead of one shape (no two generated instances are the same, and what was drawn is written down as ground truth), measured outputs (mass, shape, stiffness are measured on what was generated, not trusted from the inputs) and honest limits (each asset is checked in real engines, and what was not tested is said).

Every output is OpenUSD with standard UsdPhysics schemas, plus PhysX attributes for NVIDIA Omniverse and Isaac Sim: one file format for Blender, usdview, Omniverse and the other OpenUSD-aware tools, read back into MuJoCo for the checks. Each generator's README says in which engines its assets have been tested so far. Everything can run on CPU.

The name comes from primvar, OpenUSD's primitive variable, and varia, Latin for "diverse things".

The generators

	Generator	Assets	Physics
	Granulaire	sand, gravel, pebbles, seeds, fruit, pellets, packing peanuts; measured shapes, masses and moisture	rigid bodies; deformables for OmniPhysics (not tested yet)
	Maillage	towels, napkins, tablecloths, sheets, scarves, flags; real sizes, fabrics and masses	cloth meshes; drape test in Blender
	Filaire	standard cables with male and female connectors and the receptacles they plug into	rigid-segment chains with joints; drop, sag and insertion tests in MuJoCo
	Quincaillerie	metric screws, nuts and washers with modelled threads; battery cells and their holders	rigid bodies, springs and clips; drop, screwing and insertion tests in MuJoCo and Blender

Each generator is its own package, released on its own schedule. Primvaria installs them together and gives them one command line.

Installation

pip install primvaria             # the four generators
pip install "primvaria[all]"      # + renders, MuJoCo checks, MaterialX

Blender as a Python module is installed with pip install "maillage[blender]" (Python 3.13 only, as the bpy wheels exist for one Python version). Only one generator? Install it alone: pip install granulaire.

Usage

primvaria list                                   # generators and installed versions
primvaria granulaire generate --preset beach_sand
primvaria maillage generate --preset tea_towel
primvaria filaire generate --preset usb_c --length 2
primvaria quincaillerie generate screw M10 --with nut,washer --count 10

primvaria <generator> ... runs that generator's own command line: it is the same as typing granulaire ..., maillage ..., which keep working. From Python, import the generators directly:

from granulaire import generate_scene, write_outputs

write_outputs(generate_scene("beach_sand"), "output")

Development

The project follows GitHub Flow, like the four generators: main is protected, every change goes through a pull request from a short-lived branch (feat/<name>, fix/<name>, …), and CI must be green before merging. Enable the pre-push hook once per clone with git config core.hooksPath .githooks.

Releasing: on a chore/release-X.Y.Z branch, bump version in pyproject.toml and move the Unreleased entries of CHANGELOG.md under the new version; merge, then tag vX.Y.Z on main. The release workflow tests, builds, creates the GitHub release and publishes the package on PyPI through Trusted Publishing.

License

MIT © 2026 Daniel Régis Sarmento Caon