The U3D File Format

The U3D standard defines the syntax and semantics of the Universal 3D file format, an extensible format for downstream 3D CAD repurposing and visualization, useful for many mainstream business applications. Salient features of the U3D file format described in this document include: execution architecture that facilitates optimal run-time modification of geometry, continuous-level-of-detail, domain-specific compression, progressive data streaming and playback, free-form surfaces, key-frame and bones-based animation, and extensibility of U3D format and run-time.  The U3D file format specification does not address issues regarding rendering of 3D content.