Object Bin Packing (IRO bin_pack harmonizer)

Purpose

Procedurally pack many 3D objects into a cuboid bin (bin / pallet / container / carton) and render synthetic data (RGB, 2D/3D boxes, segmentation) — a focused specialization of object-simulation-sdg built on IRO's bin_pack harmonizer (isaacsim.replicator.object). Placement is gravity-stable: boxes are placed bottom-up and only where they rest on the bin floor or are supported from below, so no box floats in mid-air.

Read object-simulation-sdg first (the description-file schema, run modes, output layout) and action-and-event-data-generation for the launcher and env contract. This skill covers only the bin-packing specialization on top of them.

Limitations

• Requires isaacsim.replicator.object (IRO); packing runs inside a live Isaac Sim, not offline.
• bin_pack places objects gravity-stable inside a container; it does not simulate the packing motion, so it produces end-state layouts rather than a manipulation trajectory.
• Layouts vary run to run unless the config pins a seed.
• Only the scripts/bin_pack_config.py generator is offline-validated here; a live headless IRO render depends on the box set produced by demo_bin_pack.

When to use (vs siblings)

• Use this to densely pack/stack static objects into a bin by their bounding boxes — warehouse parcels, palletized cartons, shipping totes.
• For general randomized scatter placement (not packed), a table drop, or non-box geometry, use object-simulation-sdg directly.
• For moving people/robots use actor-simulation-sdg; for rare events (topple/spill) use event-generation.

Prerequisites

• Installed Isaac Sim with the Action and Event Data Generation app ($ISAAC_SIM_DIR), including isaacsim.replicator.object.core. Gravity-stable packing and fill_ratio are assumed; both are present in the build this app pins.
• NVIDIA GPU + current driver for an actual render (the offline generator needs neither).
• Env contract from isaac-sim-orchestrator: $ISAAC_SIM_DIR, $WORKSPACE_DIR, $AEDG_OUTPUT.

Available scripts

The generator packs SimReady cardboard boxes streamed from the content server — no local assets, no PATH_TO_BOXES. It derives the config version from your build with --from-ext so it stays in sync, defines the content-server macro chain inline (self-contained for a headless run), and writes a camera + dome light + output switches so the config renders as-is.

# generate a runnable config (version matched to your build)
python3 scripts/bin_pack_config.py --from-ext "$ISAAC_SIM_DIR" \
    --output-path "$AEDG_OUTPUT/iro_bin_pack" > scene_bin_pack.yaml

# partially loaded bin (~60% of bin volume), bigger bin, scale the box counts
python3 scripts/bin_pack_config.py --from-ext "$ISAAC_SIM_DIR" --output-path "$AEDG_OUTPUT/iro_bin_pack" \
    --bin-size 500 250 250 --fill-ratio 0.6 --scale-counts 1.5 > scene_bin_pack.yaml

# offline gate: confirm the config is runnable on IRO (no launch) — prints OK / problems
python3 scripts/bin_pack_config.py --from-ext "$ISAAC_SIM_DIR" \
    --output-path "$AEDG_OUTPUT/iro_bin_pack" --validate

From agent runtimes with skill-execution helpers: run_script("scripts/bin_pack_config.py", args=["--help"]).

The bin_pack harmonizer

A harmonizer correlates how multiple mutables randomize together. bin_pack packs every geometry group that references it into one cuboid, by each object's axis-aligned bounding box:

isaacsim.replicator.object:
  version: EXT_VERSION            # from the installed extension; derive with --from-ext
  # ... settings, camera, light ...
  bin_pack_H:
    harmonizer_type: bin_pack
    bin_size: [400, 200, 200]     # cuboid dimensions
    fill_ratio: 0.6               # optional (0, 1]: cap packed volume at this fraction of the bin

  boxes:
    count: 16
    type: geometry
    subtype: mesh
    tracked: true                 # only tracked mutables appear in labels/segmentation/3D boxes
    transform_operators:
    - transform:                  # <-- placement comes from the harmonizer
        distribution_type: harmonized
        harmonizer_name: bin_pack_H
        pitch: local_aabb
    - scale:
        distribution_type: range
        start: [1.2, 1.2, 1.2]
        end:   [1.25, 1.25, 1.25]
    usd_path: $[/cardboard_boxes_root]/White_A/WhiteCorrugatedBox_A08_30x30x30cm_PR_NVD_01.usd

Key behaviors:

• Gravity-stable placement — deepest-bottom-left-fill with a base-support + center-of-mass constraint; boxes rest on the floor or on boxes below them and never float.
• fill_ratio (optional, (0, 1]) — cap the total packed box volume at this fraction of the bin, for partially loaded bins. Invalid values are rejected at load.
• Layout diversity — placement is seeded, so it is reproducible per seed but varies frame to frame; different seeds give different packings.
• Overflow — objects that do not fit are moved out of view (they still exist in the stage).
• Size variety comes from choosing differently sized assets, not per-axis scale hacks; the generator curates a brown/white box set spanning ~15 cm flats to ~77 cm cubes.

Run (headless)

cd "$ISAAC_SIM_DIR"
./isaac-sim.sh --no-window --allow-root \
  --enable isaacsim.replicator.object.core \
  --/log/level=warn --/windowless=True \
  --/config/file="$PWD/scene_bin_pack.yaml"

Or in the Object SDG panel (enable isaacsim.replicator.object.core + .ui): pick demo_bin_pack from the dropdown below Simulate (it needs no local assets) and click Simulate. Extension log lines are tagged [METROPERF][isaacsim.replicator.object.core:<version>].

Verify it worked

IRO writes one folder per enabled output switch under output_path (NOT per-camera):

for d in images labels segmentation; do
  n=$(ls "$AEDG_OUTPUT/iro_bin_pack/$d" 2>/dev/null | wc -l); echo "$d: $n files"
done

A non-empty images/ with boxes packed into the bin (and, on inspection, no magenta/black boxes and no floating boxes) means it worked. An empty images/ means the run captured nothing — check tracked: true on the groups and that the version matches your build.

Integration points

• Consumes: SimReady cardboard boxes from the content server ($[/cardboard_boxes_root]/...); or your own usd_path box USDs.
• Produces: RGB + 2D/3D boxes + segmentation under output_path; can also emit captions in-run via caption_writer: CombinedIROSceneGraphWriter (see vlm-scene-captioning).
• Parent: object-simulation-sdg (schema, run modes) → action-and-event-data-generation.

Troubleshooting

• Boxes float in mid-air — the packer fell back to intersection-only checks, which means the resolved isaacsim.replicator.object.core predates gravity-stable packing. Run the app whose .kit pins the extension rather than an ad-hoc --enable.
• Magenta or near-black boxes — a White_A/Flat_A box asset attaches materials via a payload and was instanced through the scene_instance cache. The pinned build auto-disables instancing for such assets; if you still hit it, set is_instance: false on that box group.
• Bin looks sparse — the object footprints are large relative to bin_size; either enlarge --bin-size, raise --scale-counts, or add smaller box assets (unfittable boxes are teleported out of view, so raising counts alone does not densify).
• Layout not preserved after physics — physics: rigidbody makes boxes fall/reorder, discarding the bin-pack layout; omit physics to keep the packed arrangement.
• PATH_TO_BOXES errors — the shipped demo_bin_pack.yaml and this generator need no local assets; other demos (demo_bins_of_bins*, demo_table) still require PATH_TO_BOXES.
• version mismatch — set version to the installed isaacsim.replicator.object.core (use --from-ext "$ISAAC_SIM_DIR"); shipped samples can lag.