BRL-CAD is a powerful cross-platform open source combinatorial Constructive Solid Geometry (CSG) solid modeling system that includes interactive 3D solid geometry editing, a network-distributed symmetric multiprocessing high-performance ray-tracer, network-distributed framebuffer support, image and
... [More] signal-processing tools, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, numerical processing libraries, a system performance analysis benchmark suite, an embedded scripting interface, and a robust high-performance geometric representation and analysis library.
BRL-CAD is extensively cross-platform supporting Windows, Mac OS X, Linux, BSD, IRIX, Solaris, and more. BRL-CAD's development heritage of more than 20 years continues to grow. [Less]
MeshLab, a mesh processing system, for user assisted editing, cleaning, filtering and rendering of large unstructured 3D triangular meshes (typical 3D scanning meshes). The system relies for mesh processing tasks on the gpl VCG library (vcg.sf.net).
The xBIM Tookit (eXtensible Building Information Modelling) is an open-source, software development BIM tool that supports the BuildingSmart Data Model (aka the Industry Foundation Classes IFC).
xBIM allows developers to read, create and view Building Information (BIM) Models in the IFC format.
... [More] There is full support for geometric, topological operations and visualisation.
In other words, xBIM can be used to create BIM (Building Information Modelling) applications, such as Autodesk Revit Architecture [Less]