7. Glossary

Voxel block grid

A voxel block grid is a globally sparse and locally dense data structure for representing 3D scenes. It is globally sparse, as the surfaces of 2D objects generally occupy a small part of 3D space; it is locally dense, to represent contiguous surfaces.

To represent such a structure, we first roughly divide 3D space into grids of blocks. Blocks containing surfaces are organized in a hash map by 3D coordinates (globally sparse), and are then divided into dense voxels that can be accessed by array indices (locally dense). The reason we don't maintain a hash map of Dong 2021