[Bug Report] `convert_mesh.py` failed when `*.obj` file name starts with a number

[fan-ziqi]

Describe the bug

When using the convert_mesh.py script to convert .obj to .usd, if the obj file in this scene starts with a number(0c334eaabb844eaaad049cbbb2e0a4f2.obj), while the USD API prohibits names that start with a number Link. This issue is described in more detail here: Link.

Usd.Stage.Open(rootLayer=Sdf.Find('anon:0x23b593e0:tmp.usda'), sessionLayer=Sdf.Find('anon:0x23b3f000:tmp-session.usda'), pathResolverContext=<invalid repr>)
2024-10-22 11:14:00 [5,398ms] [Warning] [omni.usd] Warning: in SdfPath at line 81 of /builds/omniverse/usd-ci/USD/pxr/usd/sdf/path.cpp -- Ill-formed SdfPath </0c334eaabb844eaaad049cbbb2e0a4f2>: syntax error

Traceback (most recent call last):
  File "/home/ubuntu/workspaces/viplanner_ws/viplanner/../IsaacLab/source/standalone/tools/convert_mesh.py", line 177, in <module>
    main()
  File "/home/ubuntu/workspaces/viplanner_ws/viplanner/../IsaacLab/source/standalone/tools/convert_mesh.py", line 147, in main
    mesh_converter = MeshConverter(mesh_converter_cfg)
  File "/home/ubuntu/workspaces/viplanner_ws/IsaacLab/source/extensions/omni.isaac.lab/omni/isaac/lab/sim/converters/mesh_converter.py", line 58, in __init__
    super().__init__(cfg=cfg)
  File "/home/ubuntu/workspaces/viplanner_ws/IsaacLab/source/extensions/omni.isaac.lab/omni/isaac/lab/sim/converters/asset_converter_base.py", line 104, in __init__
    self._convert_asset(cfg)
  File "/home/ubuntu/workspaces/viplanner_ws/IsaacLab/source/extensions/omni.isaac.lab/omni/isaac/lab/sim/converters/mesh_converter.py", line 85, in _convert_asset
    asyncio.get_event_loop().run_until_complete(
  File "/home/ubuntu/anaconda3/envs/viplanner/lib/python3.10/site-packages/omni/extscore/omni.kit.async_engine/omni/kit/async_engine/async_engine.py", line 160, in run_until_complete
    return self.super_run_until_complete(future)
  File "/home/ubuntu/anaconda3/envs/viplanner/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/home/ubuntu/workspaces/viplanner_ws/IsaacLab/source/extensions/omni.isaac.lab/omni/isaac/lab/sim/converters/mesh_converter.py", line 223, in _convert_mesh_to_usd
    base_prim = temp_stage.DefinePrim(prim_path, "Xform")
pxr.Tf.ErrorException: 
	Error in 'pxrInternal_v0_22__pxrReserved__::UsdStage::_IsValidPathForCreatingPrim' at line 3340 in file /builds/omniverse/usd-ci/USD/pxr/usd/usd/stage.cpp : 'Path must be an absolute path: <>'

Perhaps we should modify the _convert_asset() function in convert_mesh.py script to throw a user-friendly warning when the mesh_file_basename does not comply with the USD file format.

This issue was first encountered in leggedrobotics/viplanner#32 (comment)

Checklist

• I have checked that there is no similar issue in the repo (required)
• I have checked that the issue is not in running Isaac Sim itself and is related to the repo