A Flexible File Format for Solid Freeform Fabrication

A flexible file format for Solid Freeform Fabrication data is presented which significantly improves on the de-facto industry standard STL format. The new format removes the redundancy present in STL files and can contain topological information. Its specification flexibility allows users to balance storage and processing costs. Since facet boundary models currently provide the greatest common denominator for data exchange between many CAD systems, they are supported by this format. Additionally, representation of CSG primitives is provided, as are capabilities to represent multiple instances of both facet and CSG solids. Format extensibility, without obsoleting existing programs, is made possible by interleaving the format schema with the data. User data can be added to existing entities, or new entities can be created. This allows the addition of NURBS based geometries in the future.