OpenVDB
Sparse volume data structure and tools
...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. The repository also includes related components such as OpenVDB AX, NanoVDB, command-line tools, and integrations for production workflows. Because it is maintained under the Academy Software Foundation, it is especially relevant for visual effects, animation, simulation, rendering, and technical graphics pipelines.