Spherical transformation error

[maxim0815]

Checklist

• [X] I have searched for similar issues.
• [X] For Python issues, I have tested with the latest development wheel.
• [X] I have checked the release documentation and the latest documentation (for master branch).

Describe the issue

Hey,

within the following examle:

https://github.com/isl-org/Open3D/blob/9238339b99afea902fb2e4a5c614699fd97f6b02/examples/python/geometry/voxel_grid_carving.py#L12

the calculation seems to be wrong. The angle calculation is:

    r_x = np.arccos(y / r)
    r_y = np.arctan2(z, x)

But shouldn't it be:

    r_x = np.arccos(z / r)
    r_y = np.arctan2(y, x)

Or am I missing something?

Steps to reproduce the bug

Calculation is wrong.

Error message

No response

Expected behavior

No response

Open3D, Python and System information

- Operating system: Ubuntu 20.04
- Python version: Python 3.8
- Open3D version: 0.15.2
- System architecture: x86
- Is this a remote workstation?: yes
- How did you install Open3D?: build from source
- Compiler version (if built from source): gcc 9.4

Additional information

No response

[nfinitedesign]

Furthermore, the example script doesn't produce the expected output anymore when using Open3D 0.17: