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roboverse_data_wuji

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SomaStacks Inc 9

Add the Isaac Sim USD for local_bottle_cap, so hand_track.open_bottle_cap can render.

metasim's IsaacSim handler spawns an ArticulationObjCfg from a USD, never from the MJCF, and
this asset shipped MJCF + URDF + .obj meshes only. Every IsaacSim run of the task therefore died
in check_assets before Kit booted. MuJoCo is unaffected (it ignores usd_path).

Generated from the MJCF — not the URDF twin, which cannot express the screw coupling — with:

python scripts/mjcf_screwcap_to_usd.py \
    --mjcf roboverse_data/assets/local_bottle_cap/bottle_cap.xml \
    --out  roboverse_data/assets/local_bottle_cap/usd/bottle_cap.usd --spawnable

Self-contained (no configuration/ sublayers), so the on-demand downloader — which walks MJCF
references but NOT USD sublayers — needs no extra_resources.

Contents: 4 meshes + 1 water cylinder, ArticulationRootAPI on the root rigid body, 3 rigid
bodies (bottle / cap_screw / cap), and the two joints under their MJCF names cap_slide +
cap_twist, chained bottle -> cap_screw -> cap. The intermediate link is what makes it a TREE:
MuJoCo allows both cap DOFs on one body, but a USD/PhysX articulation with two joints between one
body pair is a closed loop that PhysX refuses outright. The screw pitch survives as
wuji:screwPitchMPerRad customData on the prismatic joint.

Materials follow the MJCF: transmissive glass wall (ior 1.52, opacity 0.30) over a blue water
cylinder (ior 1.333), opaque plastic cap.

Verified by rendering the task end to end on Isaac Sim 5.0.0 + IsaacLab 2.2.0 with RTX Real-Time
2.0, 300 frames, in a kujiale apartment: bottle visible and held, cap present, frame mean 134.1
(healthy band 65-140).

Code side: somastacks/WUJI_SimBench PR #114.