Adding Models to the Simulator

Uploading DAE Meshes from Polycam

Requirements:

  • Blender 2.8 or higher

  • bpy Python library (install with pip install bpy)

Tested with:

  • bpy==4.0.0

  • Blender 3.0.1

Some COLLADA (.dae) files, such as those downloaded directly from Polycam, may not be fully compatible with Gazebo. To ensure compatibility, we resave these files using Blender. This step is included in the load_model.sh script, but you can also do it manually by running the blender_resave.py script.

To resave a model, run the following command:

blender -b -P blender_resave.py -- /path/to/input_file.dae /path/to/output_file.dae

Steps

  1. Export Mesh from Polycam: Download the 3D model from Polycam, then export it as a MESH in DAE format. This will create a zip folder containing the mesh and texture files.

  2. Load the Model: Use the load_model.sh script to load the model into the description package. Example:

    cd cps-gazebo-sim
./scripts/load_model.sh [-n new_name] [-d destination_directory] <zip_path>

    • -n new_name: Optionally rename the model.

    • -d destination_directory: Optionally specify a different directory to load the model into. If not provided, the model will be loaded into multi_arm_lab_sim_description/models/ by default.

Creating and Viewing Worlds

  1. Modify the Configuration File: Loaded models are available for inclusion in a world, which is an environment that contains a number of models. Worlds are defined in the multi_arm_lab_sim_gazebo package and can be configured in the worlds_config.json file.

    For example, if you loaded models named lab and ur3e, you can include them in the world configuration as follows:

    {
    "worlds": [
        {
            "name": "lab",
            "models": [
                {
                    "source_model": "lab",
                    "pose": "0 0 0 0 0 -2.5"
                },
                {
                    "source_model": "ur3e",
                    "name": "robot",
                    "pose": "0.25 0 1.5 0 0 0"
                }
            ]
        }
    ]
}

    See worlds.schema.json for details on how to customize the setup of your worlds.

  2. Create the Worlds: To generate the worlds that you configured, run the create_worlds.py script. This will produce .sdf files in the multi_arm_lab_sim_gazebo/worlds directory:

    python scripts/create_worlds.py

  3. Launch the World: Once the worlds are created, they can be used in simulator launch files. To view the statically defined world after building, run:

    ign gazebo install/multi_arm_lab_sim_gazebo/share/multi_arm_lab_sim_gazebo/worlds/<world_name>.sdf