Bilateral filter for point clouds

[overriden-sfdd]

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves Request to add bilater filtering for PointCloud #6729 Bilateral Filters in PointClouds #6891
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

A bilateral filter for point clouds is a basic noise-reducing smoothing filter algorithm requested by some users.

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[ssheorey]

Hi @overriden-sfdd thanks for this useful feature! Please add:

• C++ unit tests.
• Python bindings.

[overriden-sfdd]

@ssheorey, hey. I will be on vacation until the end of the next week. I plan to finalize the feature as soon as I come back. There is still some local integration testing I want to do. Also, we probably want to enable omp for this filter. This is the next step I've planned after the tests. Unless you suggest to create another issue and address it in another PR

[ssheorey]

Sounds good, thanks! I would suggest using TBB instead of OpenMP - we are slowly replacing OpenMP with TBB as much as possible due to better platform support for TBB and also composable parallelism. See here for a simple way to use TBB to parallelize a for loop:

Open3D/cpp/open3d/ml/contrib/IoU.cpp

Line 23 in 083210b

tbb::parallel_for(0, num_a, [&](int idx_a) {

[overriden-sfdd]

I have very little free time lately, so if anybody wants to contribute to my implementation, feel free to do so. I'm following https://www.ipol.im/pub/art/2017/179/revisions/2022-01-01/article.pdf
Currently my implementation has issues with vanishing weights. I debug this problem when I can.

[hans-hc]

Thanks for the awesome documentation, going to try and take a look at this!