Voxel Hashing

A memory-efficient 3D representation that stores only occupied voxels in a hash table (keyed by integer 3D coordinates), rather than allocating the full 3D grid. Voxel hashing enables real-time, incremental 3D reconstruction at high resolution (1-5mm) from RGB-D data. InfiniTAM and Open3D implement voxel hashing for robot mapping.