Abstract
An important problem for augmented reality is registration error. No system can be perfectly tracked, calibrated or modeled. As a result, the overlaid graphics will not align perfectly with objects in the physical world. This can be distracting, annoying or confusing. In this paper we propose a method for mitigating the effects of registration errors that enables application developers to build dynamically adaptive AR displays.
Our solution is implemented in a programming toolkit called OSGAR. Built upon OpenSceneGraph (OSG), OSGAR statistically characterizes registration errors, monitors those errors and, when a set of criteria are met, dynamically adapts the display to mitigate the effects of the errors. Because the architecture is based on a scene graph, it provides a simple, familiar and intuitive environment for application developers. We describe the components of OSGAR, discuss how several proposed methods for error registration can be implemented, and illustrate its use through a set of examples.

Reference:
Enylton Machado Coelho, Blair MacIntyre, and Simon Julier (2004) “OSGAR: A Scene Graph with Uncertain Transformations” To appear in International Symposium on Mixed and Augmented Reality (ISMAR04), November 2-5, 2004, Washington, D.C., USA.