Implementation:ARISE Initiative Robosuite USDObjects

Knowledge Sources	ARISE_Initiative_Robosuite
Domains	Robotics, 3D Rendering, USD Export
Last Updated	2026-02-15 07:00 GMT

Overview

The USDObjects module defines the object hierarchy for representing MuJoCo scene geometry as USD primitives, including abstract base objects, meshes, primitive shapes, and tendons.

Description

This module contains four classes that form the core object model for the USD exporter. The abstract base class USDObject defines the shared interface for all USD scene objects, including transform operations, visibility management, material attachment (both image-textured and solid-color), and per-frame animation updates. It creates a USD Xform node for each object and manages transform and scale operations.

Three concrete subclasses implement specific geometry types. USDMesh handles predefined mesh geometries loaded from the MuJoCo model, extracting vertex positions, face indices, and UV texture coordinates directly from the model's mesh data arrays. USDPrimitiveMesh handles primitive shapes (boxes, spheres, cylinders, etc.) by generating triangle meshes from configuration dictionaries using the shapes module. USDTendon handles tendon visualization as composite objects made of multiple sub-meshes (typically a cylinder with hemisphere caps), with independent scaling and translation for each component part.

All three subclasses support both image-based textures (with full UV mapping, BSDF shaders, and texture repeat settings) and solid-color materials with configurable metallic/roughness properties derived from the MuJoCo geom's shininess value.

Usage

Use these classes when building USD scenes from MuJoCo simulation data. They are instantiated internally by the USDExporter class and are not typically used directly. They are useful for understanding how MuJoCo geometry is mapped to USD representations.

Code Reference

Source Location

Repository: ARISE_Initiative_Robosuite
File: robosuite/utils/usd/objects.py

Signature

class USDObject(abc.ABC):
    def __init__(
        self,
        stage: Usd.Stage,
        model: mujoco.MjModel,
        geom: mujoco.MjvGeom,
        obj_name: str,
        rgba: np.ndarray = np.array([1, 1, 1, 1]),
        texture_file: Optional[str] = None,
    )

class USDMesh(USDObject):
    def __init__(
        self,
        stage: Usd.Stage,
        model: mujoco.MjModel,
        geom: mujoco.MjvGeom,
        obj_name: str,
        dataid: int,
        rgba: np.ndarray = np.array([1, 1, 1, 1]),
        texture_file: Optional[str] = None,
    )

class USDPrimitiveMesh(USDObject):
    def __init__(
        self,
        mesh_config: Dict[Any, Any],
        stage: Usd.Stage,
        model: mujoco.MjModel,
        geom: mujoco.MjvGeom,
        obj_name: str,
        rgba: np.ndarray = np.array([1, 1, 1, 1]),
        texture_file: Optional[str] = None,
    )

class USDTendon(USDObject):
    def __init__(
        self,
        mesh_config: Dict[Any, Any],
        stage: Usd.Stage,
        model: mujoco.MjModel,
        geom: mujoco.MjvGeom,
        obj_name: str,
        rgba: np.ndarray = np.array([1, 1, 1, 1]),
        texture_file: Optional[str] = None,
    )

Import

import robosuite.utils.usd.objects as object_module
# or
from robosuite.utils.usd.objects import USDObject, USDMesh, USDPrimitiveMesh, USDTendon

I/O Contract

Inputs

Name	Type	Required	Description
stage	Usd.Stage	Yes	The USD stage to add objects to
model	mujoco.MjModel	Yes	MuJoCo model instance
geom	mujoco.MjvGeom	Yes	MuJoCo visualization geom to represent
obj_name	str	Yes	Unique name for the USD object
dataid	int	Yes (USDMesh only)	Mesh data ID in the MuJoCo model
mesh_config	Dict[Any, Any]	Yes (USDPrimitiveMesh, USDTendon)	Configuration dictionary for generating primitive meshes
rgba	np.ndarray	No	RGBA color array (default: [1,1,1,1])
texture_file	Optional[str]	No	Path to texture file for image-based materials

Outputs

Name	Type	Description
usd_mesh	UsdGeom.Mesh	The USD mesh geometry representation
usd_xform	UsdGeom.Xform	The USD transform node for positioning
last_visible_frame	int	Track the last frame where the object was visible (for visibility animation)

Usage Examples

# USDMesh is typically created internally by USDExporter._load_geom()
# Example of how a mesh geom is loaded:
usd_geom = USDMesh(
    stage=stage,
    model=model,
    geom=geom,
    obj_name="robot_arm_id5_geom",
    dataid=model.geom_dataid[geom.objid],
    rgba=geom.rgba,
    texture_file=texture_files[geom.texid],
)

# Update the object position/orientation for a given frame
usd_geom.update(
    pos=geom.pos,
    mat=geom.mat,
    visible=True,
    frame=10,
)

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