The visual meshes

    roqsim_sensors/models/mid360/meshes/mid360_body.obj  (grey housing + M12 connector)
    roqsim_sensors/models/mid360/meshes/mid360_dome.obj  (laser dome window)

are derived from Livox's own Mid-360 CAD model: the official STEP assembly
`mid-360-asm.stp` (ISO-10303-21, Creo/PTC export; header FILE_NAME 'MID-360_4_ASM',
2023-01-06, author dale.chen) for the housing/dome -- published by Livox Technology among
the Mid-360 product resources at https://www.livoxtech.com/mid-360 .

The sensor's FOV is NOT a mesh here: `spawn_sensor` synthesises it at build time as a
translucent angular sector (a 360deg dome, elevation -7deg..+52deg) from the datasheet
angles in mid360.manifest.yaml, so no FOV geometry is derived from or redistributed with
the CAD.

Conversion pipeline (no geometry authored by hand):

    STEP -> OBJ    Open CASCADE tessellation via `cascadio`
                   (tol_linear=0.1 mm, tol_angular=0.5 rad)
    OBJ  -> OBJ    Blender: joined, split by CAD material into dome (Livox 'mat_2') and
                   the rest, scaled mm -> m, base dropped to z=0 (housing centred on
                   x=y=0), decimated (body ~6.5k tris, dome ~0.9k tris), exported axes
                   1:1 with Z up.

The underlying CAD geometry is Livox Technology's and its copyright remains with Livox.
Because redistribution of the derived meshes is not clearly permitted, they are generated
locally and git-ignored (external/external_assets.yaml), and mid360.xml does not reference
them: the device's housing is primitives sized from the dimensional drawing in Livox's
Mid-360 User Manual, so the model compiles in a checkout without these files. Refer to
Livox's terms before redistributing the .obj files.