Primitive Collision Proxy Storage Specification
Primitive collision proxies are derived assets. They are intended for thin rods, racks, grids, shelves, and slot-like structures where coarse convex decomposition can close functional gaps and very fine convex decomposition can create too many mesh collisions.
Do not overwrite raw meshes or upstream XML files.
Path layout
Store primitive proxy results under:
assets/<source>/derived/primitive_collision_proxies/<category>/<asset_id>/
Example for a RoboCasa dishwasher rack:
assets/robocasa/derived/primitive_collision_proxies/dishwashers/Dishwasher031_rack1_primitive_boxes_v1/
├── metadata.yaml
├── source_refs.yaml
├── README.md
├── REPORT.md
├── proxy/
│ └── primitive_collision_proxy.json
├── mjcf/
│ ├── primitive_geoms_include.xml
│ └── primitive_collision_include.xml
├── curobo/
│ └── primitive_world.yml
└── logs/
├── cuboids_summary.csv
└── proxy_generation.json
When to use this instead of convex decomposition
Use primitive proxies when the collision model must preserve gaps or slots:
- dishwasher racks
- wire baskets
- grilles
- thin support rods
- slot separators
For block-like meshes such as doors, panels, shells, and drawer fronts, prefer CoACD convex decomposition:
docs/convex_decomposition_spec.md
Source of truth
The canonical generated representation is:
proxy/primitive_collision_proxy.json
MuJoCo and cuRobo exports are generated from the same proxy JSON:
mjcf/primitive_geoms_include.xml
curobo/primitive_world.yml
This is important because simulation and planning should use the same collision approximation whenever possible.
Run primitive proxy generation
Basic command:
python scripts/run_primitive_collision_proxy.py \
assets/robocasa/raw/fixtures/dishwashers/Dishwasher031 \
--mesh visuals/rack1.obj \
--variant rack1_primitive_boxes_v1
Register a production-ready derived output in the manifest:
python scripts/run_primitive_collision_proxy.py \
assets/robocasa/raw/fixtures/dishwashers/Dishwasher031 \
--mesh visuals/rack1.obj \
--variant rack1_primitive_boxes_v1 \
--register-manifest
Do not use --register-manifest for temporary inspection runs.
Full script usage
Print current CLI help:
python scripts/run_primitive_collision_proxy.py --help
General form:
python scripts/run_primitive_collision_proxy.py <raw_asset_dir> \
--mesh <mesh_path_relative_to_raw_asset_dir> \
--variant <variant_name> \
[proxy options] \
[MJCF options] \
[repository options]
Required argument
| Argument | Meaning |
|---|---|
raw_asset_dir |
Raw asset directory under assets/<source>/raw/<asset_type>/<category>/<asset_id>/. |
Input selection
| Option | Default | Meaning |
|---|---|---|
--mesh <path> |
none | OBJ mesh to convert to primitive boxes. Path can be relative to raw_asset_dir or absolute. Repeat this option for multiple meshes. |
--mesh-glob <glob> |
visuals/rack1.obj |
Glob used when --mesh is omitted. Repeatable. |
The script currently parses OBJ geometry directly. Use OBJ input for this tool.
Repository/output options
| Option | Default | Meaning |
|---|---|---|
--variant <name> |
primitive_boxes_v1 |
Output suffix. The derived asset directory becomes <source_asset_id>_<variant>. |
--output-dir <path> |
canonical derived path | Optional explicit output directory for inspection. Do not use with --register-manifest. |
--overwrite |
false | Allow writing into an existing output directory. Use cautiously. |
--register-manifest |
false | Append the generated derived asset to manifest/assets.jsonl. Use only for outputs intended to be kept. |
Compatibility rule:
- Registered assets must use the canonical path under
assets/<source>/derived/primitive_collision_proxies/<category>/<asset_id>/. --output-diris for temporary inspection only and is rejected when combined with--register-manifest.
Proxy generation options
| Option | Default | Meaning |
|---|---|---|
--name-prefix <prefix> |
proxy |
Prefix for generated cuboid and MuJoCo geom names. |
--segment-length <float> |
0.03 |
Maximum segment length before splitting a connected component along its longest axis. Smaller values produce more/shorter boxes. |
--padding <float> |
0.001 |
Extra half-extent added to each generated cuboid. Larger values make collision more conservative. |
--min-half-extent <float> |
0.0015 |
Minimum half-extent per cuboid axis. Prevents zero-thickness boxes. |
--min-component-vertices <int> |
4 |
Discard connected components with fewer vertices. |
--min-segment-vertices <int> |
2 |
Discard split segments with fewer vertices. |
--allowed-contact-target X Y Z |
none | OBJ-local point used to mark nearby cuboids as allowed-contact. |
--allowed-contact-radius <float> |
0.03 |
Radius around allowed-contact target. Cuboids whose centers are inside this radius are marked as allowed_contact. |
The generated proxy categories are:
forbidden # exported to MuJoCo and cuRobo
allowed_contact # exported to MuJoCo for review, omitted from cuRobo forbidden world
Use allowed-contact marking for task-specific regions where contact is expected or permitted. Do not treat it as a full physical validation.
MJCF options
| Option | Default | Meaning |
|---|---|---|
--class-name <name> |
primitive_collision |
class attribute for generated <geom> entries. Empty string disables it. |
--rgba-forbidden "r g b a" |
0.8 0.1 0.1 0.45 |
RGBA for forbidden cuboids. |
--rgba-allowed "r g b a" |
0.1 0.6 1 0.45 |
RGBA for allowed-contact cuboids. |
--group <int> |
0 |
MuJoCo geom group. Empty string disables it. |
--contype <int> |
empty | MuJoCo contact type. Empty means use MuJoCo default. |
--conaffinity <int> |
empty | MuJoCo contact affinity. Empty means use MuJoCo default. |
Generated MJCF files:
mjcf/primitive_geoms_include.xml # include inside the target body
mjcf/primitive_collision_include.xml # standalone wrapper for preview/convenience
mjcf/preview_world.xml # MuJoCo preview scene with raw visual mesh + collision boxes
Recommended integration:
<!-- inside the object body that should receive primitive collision geoms -->
<include file="path/to/mjcf/primitive_geoms_include.xml"/>
For visual debugging in MuJoCo, open:
mjcf/preview_world.xml
This preview keeps the original visual mesh in gray and the primitive boxes in red.
By default, the red collision boxes are hidden. Press C in scripts/open_mujoco_preview.py to toggle them on and off.
Output files
proxy/primitive_collision_proxy.json
Contains:
- format marker
- generation params
- source mesh stats
- cuboid list
- each cuboid's name, source mesh, category, position, half-size, full dimensions, component index, and segment index
logs/cuboids_summary.csv
Tabular summary for inspection:
name
source_mesh
category
component
segment
pos_x / pos_y / pos_z
size_x / size_y / size_z # MuJoCo half-size
dim_x / dim_y / dim_z # full dimensions
Use this file to identify boxes that are too long, too thick, or unexpectedly spanning a slot.
curobo/primitive_world.yml
cuRobo cuboid fragment generated from forbidden cuboids only. allowed_contact cuboids are intentionally omitted.
REPORT.md
Human-readable generation report with mesh stats, cuboid counts, largest cuboids, and a review checklist.
Practical presets
Dishwasher rack first pass:
python scripts/run_primitive_collision_proxy.py \
assets/robocasa/raw/fixtures/dishwashers/Dishwasher031 \
--mesh visuals/rack1.obj \
--variant rack1_primitive_boxes_v1 \
--segment-length 0.03 \
--padding 0.001 \
--min-half-extent 0.0015
Finer boxes:
python scripts/run_primitive_collision_proxy.py <raw_asset_dir> \
--mesh visuals/rack1.obj \
--variant rack1_primitive_boxes_fine_v1 \
--segment-length 0.015 \
--padding 0.0005 \
--min-half-extent 0.001
Coarser boxes:
python scripts/run_primitive_collision_proxy.py <raw_asset_dir> \
--mesh visuals/rack1.obj \
--variant rack1_primitive_boxes_coarse_v1 \
--segment-length 0.06 \
--padding 0.0015 \
--min-half-extent 0.002
Review checklist
Before registering primitive proxies in manifest/assets.jsonl:
- Open or render
mjcf/primitive_geoms_include.xmlwith the visual mesh. - Confirm boxes do not bridge functional rack slots.
- Confirm boxes are not much thicker than the intended rod/wire collision margin.
- Confirm the chosen
segment-lengthis not creating too many boxes for MuJoCo or cuRobo. - Confirm allowed-contact cuboids, if used, are task-specific and documented.
- Run:
python scripts/validate_asset.py assets/<source>/derived/primitive_collision_proxies/<category>/<asset_id>
python scripts/validate_asset.py --all
Manifest rule
Primitive proxy results are real derived assets and must be indexed in:
manifest/assets.jsonl
Only register reviewed outputs that should be reused. Temporary trials should not be listed in the manifest.