BRL-CAD is a powerful Combinatorial/Constructive Solid Geometry (CSG) solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, network-distributed framebuffer support, image and signal-processing tools, and an embedded scripting language. The package is a collection of over 400 tools and utilities across over 750,000 lines of source code. Included is support for various geometric data format conversions, image and signal processing capabilities, sophisticated ray-tracing based lighting models, network distributed ray-tracing, massively parallel ray-tracing, animation capabilities, data compression, image handling, and interactive 3-D geometric editing. Included is an implementation of Weiler's n-Manifold Geometry (NMG) data structures for surface-based solid models and photon mapping.