[OVPHYSX] SceneDataProvider

[AntoineRichard]

Summary

Implement OvPhysxSceneDataProvider for the OVPhysX backend, satisfying the BaseSceneDataProvider contract. Enables Newton-based visualizers (Rerun, Viser) to display OVPhysX simulations.

Scope

• ovphysx_scene_data_provider.py (~400 lines)
• Factory registration in scene_data_provider.py (~5 lines)
• Build Newton model from USD for visualization (share code with PhysX approach)
• Sync ovphysx body transforms into Newton state on each update

No OVPhysX API Blockers

Uses existing body transform bindings. No new ovphysx APIs needed.

Dependencies

• Requires PR ovphysx backend integration #4852 merged
• Independent of asset/sensor specs

Spec

Full design spec: docs/superpowers/specs/2026-04-20-ovphysx-scene-data-provider-design.md

Parent issue: #5315

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📋 Full Design Spec (click to expand)

OVPhysX SceneDataProvider — Design Spec

Issue: Needs creation — [OVPHYSX] SceneDataProvider
Date: 2026-04-20
Status: Draft

Summary

Implement OvPhysxSceneDataProvider for the OVPhysX backend, satisfying the BaseSceneDataProvider contract. This enables Newton-based visualizers (Rerun, Viser) to display OVPhysX simulations by providing body transforms and metadata.

The OVPhysX approach is closer to Newton's implementation (delegation to physics manager) than PhysX's (which builds its own Newton model from USD). OVPhysX has direct access to body transforms via TensorBindings and does not need Kit/Fabric.

Contract to Satisfy

BaseSceneDataProvider (source/isaaclab/isaaclab/physics/base_scene_data_provider.py)

Method	Signature	Purpose
update	(env_ids: list[int] | None) -> None	Refresh cached transforms
get_newton_model	() -> Any | None	Newton model handle (for viz)
get_newton_state	(env_ids) -> Any | None	Newton state handle
get_usd_stage	() -> Any | None	USD stage handle
get_metadata	() -> dict[str, Any]	Backend metadata
get_transforms	() -> dict[str, Any] | None	Body positions + orientations
get_velocities	() -> dict[str, Any] | None	Body velocities
get_contacts	() -> dict[str, Any] | None	Contact data (can return None)
get_camera_transforms	() -> dict[str, Any] | None	Camera transforms (can return None)

Architecture

File Layout

source/isaaclab_ovphysx/isaaclab_ovphysx/scene_data_providers/
├── __init__.py
├── __init__.pyi
└── ovphysx_scene_data_provider.py  (~400 lines)

Implementation Approach

OVPhysX's situation is unique:

• Like Newton: The physics engine is the source of truth for transforms (no Kit/Fabric layer)
• Unlike Newton: OVPhysX doesn't have a native Newton model — it uses PhysX underneath
• Like PhysX: It may need to build a Newton model from USD for visualization

Recommended approach: Follow PhysX's pattern — build a Newton model from the USD stage at initialization, then sync OVPhysX body transforms into Newton state on each update() call. This enables all Newton-based visualizers without requiring changes to the visualizer stack.

ovphysx_scene_data_provider.py:

1. __init__(stage, sim_context):

   • Store references to USD stage and OvPhysxManager
   • Lazy-build Newton model on first access

2. update(env_ids):

   • Read body transforms from ovphysx TensorBindings
   • Write transforms into Newton model state
   • For partial updates, only sync requested env_ids

3. get_newton_model():

   • Build Newton model from USD if not yet built (same as PhysX approach)
   • Return cached model

4. get_newton_state(env_ids):

   • Return Newton state (synced in update())
   • Filter for env_ids if specified

5. get_transforms():

   • Read body poses from ovphysx bindings
   • Return as {"positions": ..., "orientations": ...} dict

6. get_velocities():

   • Read body velocities from ovphysx bindings
   • Return as {"linear": ..., "angular": ...} dict

7. get_usd_stage():

   • Return the USD stage handle (OVPhysX loads from USD, so stage is available)

8. get_metadata():

   • Return {"physics_backend": "ovphysx", "num_envs": N}

9. get_contacts() / get_camera_transforms():

   • Return None (not supported initially)

OVPhysX API Requirements

API	Purpose	Notes
Body transforms	All body poses for visualization	Available via existing bindings
Body velocities	Optional velocity visualization	Available via existing bindings

No new ovphysx APIs needed for the core implementation.

Newton Model Building

The Newton model building logic can be shared with PhysX's implementation:

• Uses ModelBuilder to construct from USD
• Handles prebuilt artifacts for fast loading
• Maps body indices to environment indices

Consider extracting the Newton model building code from PhysxSceneDataProvider into a shared utility if significant code overlap exists.

Factory Registration

Add "ovphysx" to the factory dispatch in source/isaaclab/isaaclab/physics/scene_data_provider.py:

if backend_name == "ovphysx":
    from isaaclab_ovphysx.scene_data_providers import OvPhysxSceneDataProvider
    return OvPhysxSceneDataProvider(stage, sim_context)

Also update source/isaaclab/isaaclab/utils/backend_utils.py if needed.

Tests

No existing SceneDataProvider tests to copy. Write basic tests:

• Verify get_metadata() returns correct backend name
• Verify get_transforms() returns valid body poses after simulation steps
• Verify update() syncs transforms correctly

Dependencies

• Requires PR ovphysx backend integration #4852 merged
• No new ovphysx APIs needed
• Depends on Newton model builder (shared with PhysX)
• Independent of asset/sensor specs (reads from physics manager directly)

Estimated Scope

• ovphysx_scene_data_provider.py: ~400 lines
• Factory registration: ~5 lines
• Tests: ~100 lines