Target simulators and exports

The Simulator global setting decides two things: which engine validates the asset, and which package format the export leads with. You can switch simulators on a finished asset and Reprocess; no regeneration needed.

Choosing

	Isaac Sim	MuJoCo	Newton
Package	USD (`.usd` / `.usdc`) with PhysX schemas	MJCF (`.xml`) + OBJ meshes	USDA with Newton physics schemas
Best for	NVIDIA stack, Isaac Lab, articulation validation, photoreal rendering	Fast RL, large parallel rollouts, contact-rich manipulation	Soft bodies, cloth, cables, deformables; Isaac Lab with Newton
Collision options	Convex (Low to Extra high) and SDF	Convex	Convex
Physics type	Rigid	Rigid	Rigid and Soft body
Articulation	Full (revolute, prismatic, fixed, continuous, drives)	Full	Full
Validation	Rest, joint range, penetration, drop	Rest, joint range, penetration	Rest, joint range, soft-body settle

Export package

Export on a READY asset downloads a ZIP. Contents are the same across simulators except for the lead package.

<asset_name>/
├─ sim/
│  ├─ <asset_name>.usd          # Isaac Sim  (or .xml for MuJoCo, .usda for Newton)
│  ├─ collision/                # per-part convex hulls (.obj) or SDF data
│  └─ textures/                 # PBR maps referenced by the package
├─ mesh/
│  ├─ <asset_name>.obj + .mtl   # visual mesh, real-world scale, authored up axis
│  └─ <asset_name>.glb
├─ textures/
│  ├─ <part>_diffuse.png, _roughness.png, _metallic.png, _normal.png
│  ├─ texture_manifest.json     # which map goes on which part
│  └─ materials_manifest.json   # material names and parameters
├─ physics.json                 # per-part mass, COM, inertia, friction, restitution, joints
├─ report.json                  # validation results and settings used
└─ preview.png

physics.json is the same data the Properties tab shows. report.json records the settings and validation checks associated with that export.

Exporting and downloading are free. After an asset has been exported, further in-place reruns show a quote before they run. Tokens.

Loading

Isaac Sim: File > Open the .usd, or reference it into your stage. Inspect the imported articulation and collision settings before running your simulation. Textures resolve relative to the USD.
MuJoCo: mujoco.MjModel.from_xml_path("sim/<asset>.xml"). Mesh and texture paths in the MJCF are relative to the sim/ folder; keep the folder structure.
Newton / Isaac Lab: load the .usda as a Newton asset; soft-body parts carry the Newton deformable schema.
Other engines: use the standard mesh, physics, and collision files as inputs to your engine-specific import workflow. Exact compatibility depends on the target engine.

Units and up axis

The package is written in the Units and Up direction from the pipeline settings. If your scene is Z-up metres and the export is Y-up centimetres, set those two settings and Reprocess rather than transforming in the target tool.

Common import problems

White asset in usdview / Blender / macOS Preview: those viewers don’t render MDL materials. The package includes a UsdPreviewSurface binding as well, so this should render textured; if not, check that textures/ travelled with the USD.
MJCF can’t find meshes: the ZIP was flattened. Keep sim/ and its subfolders together.
Object falls through the floor: units mismatch (a 1000x scale error) or collision hulls missing for a part. Check the Collision view before export.
Joint moves the wrong way: the joint axis is authored in the part’s local frame; re-check in the Physics view and edit the axis, then Apply Edits and re-export.