Ptex is a texture mapping system developed by Walt Disney Animation Studios for production-quality rendering:
No UV assignment is required! Ptex applies a separate texture to each face of a subdivision or polygon mesh.
The Ptex file format can efficiently store hundreds of thousands of texture images in a single file.
The Ptex API provides cached file I/O and high-quality filtering - everything that is needed to easily add Ptex support to a production-quality renderer or texture authoring application.