Feat: VoxelGrid transform, rotate, translate and scale

[lmuffang]

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves Translate not implemented for VoxelGrid geometry #3361
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

It was not possible to move around this type of geometry before.

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

This pr implements the Transform, Rotate, Translate and Scale methods for the VoxelGrid object in cpp.
It introduces an origin_transform_ attribute to be able to rotate the grid origin easily and efficiently, keeping all voxels indexes the same.
Python bindings and docs seem to be already done for these methods.

[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.

[Copilot]

Pull Request Overview

This PR implements geometric transformation methods (Transform, Rotate, Translate, and Scale) for the VoxelGrid class, addressing issue #3361. The implementation introduces an origin_rotation_ attribute to efficiently handle rotations without modifying individual voxel indices.

Key changes:

• Added origin_rotation_ matrix attribute to VoxelGrid for tracking grid orientation
• Implemented Transform, Rotate, Translate, and Scale methods using lazy transformation approach
• Updated PLY I/O to serialize/deserialize the rotation matrix

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
cpp/tests/geometry/VoxelGrid.cpp	Added comprehensive unit tests for Scale, Translate, Rotate, and Transform operations
cpp/pybind/geometry/voxelgrid.cpp	Exposed origin_rotation attribute to Python API
cpp/open3d/visualization/shader/SimpleShader.cpp	Updated vertex calculation to incorporate origin rotation matrix
cpp/open3d/visualization/rendering/filament/FilamentGeometryBuffersBuilder.cpp	Updated mesh generation to apply rotation transformation
cpp/open3d/io/file_format/FilePLY.cpp	Added serialization/deserialization support for origin_rotation matrix
cpp/open3d/geometry/VoxelGrid.h	Declared new rotation attribute and GetAllVoxelCorners helper method
cpp/open3d/geometry/VoxelGrid.cpp	Implemented transformation methods and updated bound calculations

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[ssheorey]

Looks good! Thanks for adding this missing feature. Can you please rename origin_rotation_ to just rotation_ for clarity?

[ssheorey]

Thanks @lmuffang Looks good. We can merge once CI passes.