ARToolKit - Open Source Video Tracking

ARToolKit is a software library for building Augmented Reality (AR) applications. These are applications that involve the overlay of virtual imagery on the real world.

The ARToolKit video tracking libraries calculate the real camera position and orientation relative to physical markers in real time. This enables the easy development of a wide range of Augmented Reality applications. Some of the features of ARToolKit include:

• Single camera position/orientation tracking.
• Tracking code that uses simple black squares.
• The ability to use any square marker patterns.
• Easy camera calibration code.
• Fast enough for real time AR applications.
• SGI IRIX, Linux, MacOS and Windows OS distributions.
• Distributed with complete source code.

More information is available here.