CoACD (Collision-Aware Approximate Convex Decomposition)

A tool that automatically slices a mesh into a set of convex chunks for use as a physics engine's collision shape.

CoACD is an open-source approximate convex-decomposition tool from Hao Su's group at UC San Diego (Wei et al., SIGGRAPH 2022). Physics engines compute collisions fastest against convex shapes, but simulation assets are usually arbitrarily shaped triangle meshes, which are slow and unstable to use directly; the older, commonly used V-HACD tends to fill in important concave structures — a cup's rim, the gap of a drawer — making grasping and insertion tasks impossible to simulate correctly. CoACD explicitly accounts for collision-aware concavity during decomposition and uses a tree search to choose where to cut, preserving those structures. In practice, an OBJ or STL is run through the tool once, and the resulting set of convex pieces is written into a URDF's or MJCF's collision fields.

ExampleBefore importing a cup or piece of furniture's mesh into MuJoCo or Isaac Sim, run it through CoACD first to generate convex collision geometry, so the gripper doesn't fail to fit into the cup's opening.

Also called

CoACD

Related

Convex Decomposition · Collision Geometry (Collider) · Simulation Assets · Mesh File (STL / OBJ / DAE / glTF) · Unified Robot Description Format · MJCF (MuJoCo XML Format)

Sources

CoACD - GitHub