OpenVDB
Sparse volume data structure and tools
OpenVDB is an open-source C++ library for storing and manipulating sparse volumetric data on three-dimensional grids. It was originally developed by DreamWorks Animation for volumetric work in feature film production. The project centers on a hierarchical data structure that keeps large empty regions efficient while still supporting detailed volume information. It includes tools for creating, editing, transforming, filtering, rendering, and exchanging volume data.