Fix legacy OVRTX cloning of instanced geometry and unused variants

[ooctipus]

Legacy OVRTX cloning drops nested instanced geometry, leaving Franka robots visible only in environment 0. Expand instances in the renderer's temporary USD export, while preserving the simulation stage and the ovstage and single-environment paths. Export only clone-plan rows with active destinations: unused variants intentionally retain placeholder paths without spawning USD prims.

The production franka_panda.usda reported Last-Modified: Tue, 15 Sep 2026 22:49:27 GMT and switched from base.usda to compact collider payloads containing instanced visual groups. Export deinstancing directly reproduces and fixes the missing clones; attribution to that external asset publication is an inference from its composition and timing, and no asset source commit is available. The first fix in #7865, commit 3ce2ea18f, introduced the confirmed Kuka regression by expanding inactive source paths (/World/envs/env_4/Object with 16 variants and four environments); this change handles both cases at the renderer export boundary.

Validation:

• Red/green regression for 16 variant rows and four spawned environments; the legacy path failed on the absent fifth source before filtering, while the ovstage control passed.
• 52 USD export and clone-plan tests passed, including nested instances and unchanged input layers.
• All 16 legacy Newton/OVRTX rendering cases passed: 12 Franka cloth, soft-body and cable cases plus four heterogeneous Kuka cases. All 47 golden PNGs were verified against the base commit's LFS SHA-256 values; images and comparison thresholds are unchanged.
• uv run --no-sync isaaclab -f passed. GPU comparisons passed in 94.72 seconds with the existing shader cache; an initial cold-cache attempt reached its five-minute watchdog after two passing cases.

Local GPU validation uses the existing environment's Newton 1.6.0rc1; CI resolves stable 1.6.0.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge; the changed export behavior is narrowly scoped and covered by targeted regressions.

Summary

This PR repairs legacy OVRTX cloning of nested instanced USD geometry while avoiding exports of inactive variant placeholders.

• Filters clone-plan export sources to rows with at least one active destination.
• Expands nested instances only in the legacy renderer’s anonymous export stage.
• Preserves instancing in the simulation stage, ovstage path, and single-environment path.
• Adds regression coverage for inactive variants, nested instances, mode selection, and unchanged input layers.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Prepare simulation stage] --> B[Build active source list]
  B --> C{Multiple environments?}
  C -- No --> D[Export original stage]
  C -- Yes --> E{Legacy OVRTX path?}
  E -- Yes --> F[Expand source instances in anonymous session]
  F --> G[Keep environment-root placeholders]
  E -- No --> H[Retain source instancing]
  H --> I[Trim destination environment roots]
  G --> J[Export temporary USDA]
  I --> J
  J --> K{Renderer path}
  K -- Legacy --> L[renderer.clone_usd]
  K -- ovstage --> M[stage.clone]

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_{Reviews (1) · Last reviewed commit: "Preserve instanced visuals when cloning ..."}

[isaaclab-review-bot]

Isaac Lab Review Bot

The patch filters inactive clone-plan source rows before export and expands nested USD instances only in the temporary legacy OVRTX export. The live simulation stage, ovstage path, and single-environment export retain existing instancing behavior.

• Design and architecture: The de-instancing is appropriately confined to the existing legacy keep_env_roots branch and anonymous export session. The original clone plan remains intact for scale capture, clone queries, and backend row indexing.
• API: No public signature or default changes. export_stage_to_string retains its existing parameters and single-environment behavior, while its documentation and the isaaclab_ov changelog fragment describe the changed legacy export behavior.
• Implementation: The active-source filter removes all-false clone-mask rows before export, avoiding placeholder paths with no corresponding prim. Tests cover inactive variant rows in both renderer paths, nested-instance expansion only in legacy multi-environment exports, and preservation of the input stage. De-instancing may increase temporary USDA size for heavily instanced assets, but it is scoped to the affected legacy export path.

No blocking issues. No inline issue met the actionable-evidence threshold; the assessment above records the review feedback.

Automated review; human maintainers own approval decisions.

[maxkra15]

run-ci

[kellyguo11]

is this supposed to be required? does this happen pre or post cloning?

[maxkra15]

this is for legacy renderer.clone_usd() path, becuase it currently drops geometry beneath nested USD instances - instead we expand instances in the temporary export before OVRTX loads and clones it. it does not modify the simulation stage, and the ovstage path skips the workaround and retains instancing. this is pre cloning

[kellyguo11]

would it impact the rendering performance? if we make visual geometries not instanceable, it normally increases the memory usage quite a bit.

[maxkra15]

run-ci