Create albedo texture for a model from calibrated images

[ssheorey]

Create an albedo for the triangle mesh using calibrated images. The triangle mesh must have texture coordinates (texture_uvs triangle attribute). This works by back projecting the images onto the texture surface. Overlapping images are blended together in the resulting albedo. For best results, use images captured with exposure and white balance lock to reduce the chance of seams in the output texture. Two BlendingMethod s for overlapping images are supported:

• MAX: For each texel, pick the input pixel with the max weight from all overlapping images. This creates sharp textures but may have visible seams.
• AVERAGE: The output texel value is the weighted sum of input texels. This creates smooth blending without seams, but the results may be blurry.

TODO:

• [ ] Auto exposure / color balance between different input images.
• [ ] Fine-tune input camera poses.

Type

• [ ] Bug fix (non-breaking change which fixes an issue): Fixes #
• [x] New feature (non-breaking change which adds functionality). Resolves #
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

This feature can be used to create more realistic 3D models with Open3D, e.g. RGBD reconstruction pipeline currently creates a 3D mesh with per-vertex colors only. This adds high resolution textures for a more photorealistic appearance, even with simplified / low poly meshes.

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.

Example

Rendered images:

https://github.com/isl-org/Open3D/assets/41028320/be1fce42-4673-4666-8466-47af59cd452c

Created albedo:

[update-docs[bot]]

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