Orientation issue for small meshes

[snasiriany]

For models that have small meshes, I was seeing the issue Error: mesh volume is too small...

I'm able to make this issue go away by adding the following line to the body containing the meshes: <inertial pos="0 0 0" mass="0" diaginertia="0 0 0"/>

Adding this line resolves the error, but the offending small mesh is oriented incorrectly:

I've noted that the orientation issue goes away when I increase the scale parameter of the meshes to a large enough value:

Attaching a zip file with minimal models here: small_model_2.zip

To reproduce: python -m mujoco.viewer --mjcf small_model_2/model_small_scale.xml

I believe this is a bug.

• System information:
  • Operating system: both Mac (M1), Ubuntu
  • MuJoCo version: 2.3.7

[kevinzakka]

Add shellinertia=true to the Hood_light_2 geom and your problem should go away.

[snasiriany]

Thanks @kevinzakka! That did solve it, but it should only be used if the geom is small. In the larger model with 100x scale, I need to make that shellinertia=false. Is there a way to determine this automatically? Perhaps a good feature to implement in the future.

[quagla]

Why do you need to make it false? My intention was that shellinertia should only have been dependent on the mesh topology, not its size.