| # Objects |
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| Objects are USD assets used in manipulation tasks. Each object is a self-contained `.usd` or `.usda` file with physics properties (rigid body, collision, mass, friction) that make it graspable and simulatable in IsaacSim. |
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| RoboLab ships several object datasets in [`assets/objects/`](../assets/objects/): |
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| | Dataset | Description | |
| |---------|-------------| |
| | `ycb` | YCB object set | |
| | `hope` | HOPE household objects | |
| | `hot3d` | HOT3D objects | |
| | `handal` | HANDAL objects | |
| | `vomp` | VOMP object set | |
| | `fruits_veggies` | Fruits and vegetables | |
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| The full inventory is in [`assets/objects/object_catalog.json`](../assets/objects/object_catalog.json), and a visual table is in [`assets/objects/README.md`](../assets/objects/README.md). |
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| ## Creating New Objects |
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| This requires experience with the IsaacSim GUI and assumes you have object meshes ready. |
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| ### File layout |
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| Place objects under a dataset folder: |
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| ``` |
| assets/objects/ |
| my_dataset/ |
| banana/ |
| banana.usd |
| textures/ |
| banana_diffuse.png |
| mug.usd |
| ``` |
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| Use simple names (`object_name.usd`). Objects can either live directly in the dataset folder or in a subdirectory with a `textures/` folder alongside. |
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| ### USD requirements |
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| - **`defaultPrim`** — Must be the top-level prim, named the same as the file (e.g., `/banana` for `banana.usd`). |
| - **RigidBodyAPI** — Applied to `defaultPrim`. Only one prim in the entire tree should have `RigidBodyAPI`. |
| - **Collision** — Use `physxSchema` collision API with `convexDecomposition` (vertices: 256, shrinkwrap: 0.01). Do **not** use `UsdPhysics` collision API. |
| - **Mass** — Apply `MassAPI` to `defaultPrim` (use either density or mass). |
| - **Friction** — Static and dynamic friction from 2.0–5.0 for reliable grasping. |
| - **Attributes** — `defaultPrim` should contain `description`, `class`, and `dataset` attributes describing the object. |
| - **Textures** — All texture paths must be relative to the USD file. Do not use absolute paths or paths pointing outside the repo. |
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| ### Workflow |
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| After creating your objects: |
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| 1. **(Optional) Convert format** — Convert between binary and ASCII USD: |
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| ```bash |
| python assets/objects/_utils/convert_usd_format.py my_dataset --to-usda |
| python assets/objects/_utils/convert_usd_format.py my_dataset --to-usd |
| ``` |
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| 2. **Set physics properties** — Batch-update friction and restitution on all objects: |
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| ```bash |
| python assets/objects/_utils/update_object_properties.py assets/objects/my_dataset \ |
| --static 5.0 --dynamic 5.0 |
| ``` |
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| 3. **Generate the catalog** — Scan objects and build `object_catalog.json`: |
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| ```bash |
| python assets/objects/_utils/generate_catalog.py |
| python assets/objects/_utils/generate_catalog.py --objects assets/objects/my_dataset # specific directory |
| ``` |
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| 4. **(Optional) Generate screenshots** — Render preview images (requires IsaacSim): |
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| ```bash |
| python assets/objects/_utils/generate_object_screenshots.py --datasets my_dataset |
| ``` |
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| 5. **Generate the README** — Build the markdown table from the catalog: |
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| ```bash |
| python assets/objects/_utils/generate_readme.py --datasets my_dataset |
| ``` |
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| ### Inspecting the catalog |
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| List all semantic class labels: |
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| ```bash |
| python assets/objects/_utils/generate_catalog.py --list-classes |
| python assets/objects/_utils/generate_catalog.py --list-classes --by-dataset |
| python assets/objects/_utils/generate_catalog.py --list-classes --by-dataset --verbose |
| ``` |
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| ## Using Objects in Scenes |
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| Objects are placed into USD scenes by dragging them into the IsaacSim viewport (see [Scenes](scene.md)). When a task references objects via `contact_object_list`, the names must match the prim names in the scene. |
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| ## Utility Script Reference |
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| All scripts live in [`assets/objects/_utils/`](../assets/objects/_utils/README.md). |
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| | Script | Purpose | |
| |--------|---------| |
| | `generate_catalog.py` | Scan objects and build `object_catalog.json` | |
| | `generate_readme.py` | Build markdown README table from catalog | |
| | `generate_object_screenshots.py` | Render preview images (requires IsaacSim) | |
| | `update_object_properties.py` | Batch-update friction, restitution on USD files | |
| | `convert_usd_format.py` | Convert between `.usd` (binary) and `.usda` (ASCII) | |
| | `common.py` | Shared helpers (`iter_object_files`, `load_catalog`, etc.) | |
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| ## See Also |
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| - [Scenes](scene.md) — Creating USD scenes that contain objects |
| - [Tasks](task.md) — Defining tasks that reference objects via `contact_object_list` |
| - [`assets/objects/README.md`](../assets/objects/README.md) — Visual catalog of all objects |
| - [`assets/objects/_utils/README.md`](../assets/objects/_utils/README.md) — Quick reference for utility scripts |
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