osgART is a cross platform toolkit for developing AR applications with the OpenSceneGraph API. osgART was invented by Julian Looser and then made by Raphael Grasset and Hartmut Seichter into a robust software framework with hundreds of useful features. The current working version is 2.x and is available from the osgART Website. osgART is been used in hundreds if not thousands of AR applications in research, education and commercial applications. It is most likely the most used open source AR application framework.