Hermes (formerly Sparc3D SDF)

A fast SDF preprocessing library for meshes built on the ops provided in Kaolin, and referencing the approach described in Sparc3D.

This originally a reference implementation using Kaolin based on the Sign distance field preprocessing described in the Sparc3D paper / arXiv (which had/has not released their code, 2025-09-13).

Installation:

See INSTALL.md

Usage

Example script: scripts/sdf.py.

python scripts/sdf.py -i assets/plane.obj --N 1024 -o plane_1024.obj

Calculates the SDF for the provided assets/plane.obj from Objaverse at $1024^3$ in under $30$ s with less than 16 GB VRAM.

Open TODOs

[ ] Render refinement? [ ] Improve the flood-fill extraction, see https://github.com/isl-org/unifi3d/blob/374201a23f2a3c36c8e595eec9431b77df8c08fa/scripts/compare_sdf.py#L31

## Opinions on the Sparc3D method My implementation of the flood-fill step the most conservative approach. The Intel Labs / Unifi3d version (which was just released now) is a much more nuanced approach:

1. Identify the barrier based on distance to mesh being < cell size in all 3 axes independently.
2. Average See also my notes on why the Sparc3D displacement step was unneccessary and harmful: https://ben-kaye.github.io/projects/1_sparc3d/