# Description

With at least Isaac Sim 2023.1 (not checked on 2022.2.1), the URDF
importer from Isaac Sim seems to save the material paths as absolute
when trying to save the asset in its instanceable format. The material
paths are relative when the USD is generated as non-instanceable.

This MR fixes this behavior by adding a post-processing step that
iterates over the instanced mesh file and resolves all paths to become
relative.

You can use the tool by running the following:

```bash
./orbit.sh -p source/tools/convert_urdf.py ~/git/anymal_d_simple_description/urdf/anymal.urdf source/extensions/omni.isaac.orbit_assets/data/Robots/ANYbotics/ANYmalD/anymal_instanceable.usda --merge-joints --make-instanceable
```

## Type of change

- Bug fix (non-breaking change which fixes an issue)
- New feature (non-breaking change which adds functionality)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file