Add ColorHashTSDFVolume implementation #27823
# Add ColorHashTSDFVolume implementation [[#25155](https://github.com/opencv/opencv/issues/25155)]
## Description
Added a new ColorHashTSDFVolume implementation that combines the benefits of HashTSDFVolume's efficient spatial hashing with color support. This provides memory-efficient RGB-D fusion with better performance compared to regular ColorTSDFVolume.
### Key Features
- Hash-based spatial data structure for efficient storage
- Color integration during volume updates
- Raycast with color interpolation
- Compatible with existing TSDF interfaces
- CPU implementation with parallel processing support
### Implementation Details
- Added new ColorHashTSDFVolume class with create() factory method
- ColorVoxel structure combining TSDF and RGB data
- Spatial hashing for efficient voxel lookup
- Weighted running average for color updates
- Trilinear interpolation during raycasting
- Unit tests for basic operations and edge cases
### Files Modified/Added
- modules/3d/src/rgbd/color_hash_volume.hpp - New header defining ColorHashTSDFVolume interface
- modules/3d/src/rgbd/color_hash_volume.cpp - Implementation of ColorHashTSDFVolume
- modules/3d/test/test_color_hash_volume.cpp - Unit tests
### Performance
The implementation uses spatial hashing to only store voxels near surfaces, significantly reducing memory usage compared to regular ColorTSDFVolume while maintaining similar processing speed.
### Testing
Added unit tests that verify:
- Basic integration and raycasting operations
- Empty volume handling
- Memory usage patterns
### Future Work
- GPU/OpenCL implementation
- Additional color interpolation methods
- Extended comparison tests with other volume types
Dedicated pointcloud module #29224
OpenCV contrib: https://github.com/opencv/opencv_contrib/pull/4134
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
Arman Rostami
Alexander Smorkalov