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URDF Export Extension [isaacsim.asset.exporter.urdf]#

URDF Exporter API#

The URDF exporter provides a Python API for converting USD articulated robots to URDF format. Below is a sample demonstrating how to export a robot from an open USD stage.

 1import omni.usd
 2from isaacsim.asset.exporter.urdf import UsdToUrdfConverter
 3
 4# Get the current stage.
 5stage = omni.usd.get_context().get_stage()
 6
 7# Configure and export.
 8converter = UsdToUrdfConverter(
 9    stage=stage,
10    root_prim_path=None,       # Uses the default prim
11    mesh_dir_name="meshes",
12    mesh_path_prefix="./",
13)
14
15output_path = converter.convert("/tmp/my_robot.urdf")
16print(f"Exported URDF to: {output_path}")
class UsdToUrdfConverter(
stage: Usd.Stage | str | os.PathLike,
root_prim_path: str | None = None,
mesh_dir_name: str = 'meshes',
mesh_path_prefix: str = './',
visualize_collision_meshes: bool = False,
variant_selections: dict[str, str] | None = None,
)#

Convert a USD stage’s articulated robot to URDF.

Discovers robot structure from physics graph, reads link/joint/material data, exports meshes to OBJ, and writes URDF XML.

Parameters:

  • stage – An open Usd.Stage or a file-system path (str / os.PathLike) to a USD file (.usd, .usda, .usdc). When a path is given the stage is opened with Usd.Stage.Open.

  • root_prim_path – Prim path of the articulation root. None uses the stage default prim.

  • mesh_dir_name – Subdirectory name for exported mesh files.

  • mesh_path_prefix – Path prefix written into URDF mesh references.

  • visualize_collision_meshes – If True, duplicate collision meshes as visual geometry.

  • variant_selections – Optional mapping of variant-set names to variant selections to apply on the root prim before conversion. For example {"Physics": "PhysX", "LOD": "high"}. Selections are applied before robot discovery, so the chosen composition arcs determine which links, joints, and meshes are exported. Variant sets that already have a selection are overridden.

Initialize the converter; see class docstring for parameter descriptions.

convert(output_path: str | None = None) → str#

Convert the USD stage to URDF and write to output_path.

When output_path is None the URDF is written next to the source USD file using the same base name (robot.usd -> robot.urdf). For stages loaded from omniverse:// URLs, omni.client is used to parse the source path; if the source is remote the current working directory is used as the output location.

Raises:

ValueError – If output_path is None and no source path can be determined from the stage.