CTM (OpenCTM)

The CTM file format is a 3D triangle mesh format that contains 3D geometry such as vertices, faces, and face normals. The format was devised and released in 2010 with the intention of creating 3D models that could be compressed and easily distributed.

The compression methods employed by the CTM format can be lossy or lossless. The lossy compression will attempt to simplify the mesh vertices to reduce the space needed to store them, while the lossless method employs the LZMA compression library. The format has its own dedicated CTM viewer application, though the format is not well supported by other 3D modeling applications.