Open Source

Ptex

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.

Motivation

There were many drawbacks to traditional texture mapping methods that led to the development of Ptex:

UV assignment was a tedious task, and making good UVs on complex models was difficult.
Texture seams could produce visible artifacts especially with displacement maps.
Large numbers of texture files were required creating a significant I/O bottleneck.

Ptex addresses all these issues by eliminating UV assignment, providing seamless filtering, and allowing any number of textures to be stored in a single file.

Ptex has been used on virtually every surface of every Walt Disney Animation Studios production since 2008.

Features

Supports Catmull-Clark subdivision surfaces (including quad and non-quad faces), Loop subdivision surfaces, and polymeshes (either all-quad or all-triangle).
Several data types are supported including 8 or 16-bit integer, float, and half-precision float.
An arbitrary number of channels can be stored in a Ptex file.
Arbitrary metadata can be stored in the Ptex file and accessed through the memory-managed cache.

File Format

Ptex uses a custom file format that is designed specifically for efficient rendering. A Ptex file can store an arbitrary number of textures along with mipmaps and adjacency data used for filtering across face boundaries.

References

See the paper, Ptex: Per-Face Texture Mapping for Production Rendering, Brent Burley and Dylan Lacewell, Eurographics Symposium on Rendering 2008.
View the slides from the Eurographics presentation as Powerpoint or pdf.
Watch a demonstration of the Ptex painting workflow.