CALIBRATION REQUIREMENTS AND PROCEDURES FOR A MONITOR-BASED AUGMENTEDREALITY SYSTEM

Augmented reality entails the use of models and their associated rende rings to supplement information in a real scene, In order for this inf ormation to be relevant or meaningful, the models must be positioned a nd displayed in such a way that they blend into the real world in term s of alignments, perspectives, illuminations, etc, For practical reaso ns the information necessary to obtain this realistic blending cannot be known a priori, and cannot be hard-wired into a system, Instead a n umber of calibration procedures are necessary so that the location and parameters of each of the system components are known, In this paper we identify the calibration steps necessary to build a computer model of the real world and then, using the monitor-based augmented reality system developed at ECRC (GRASP) as an example, we describe each of th e calibration processes, These processes determine the internal parame ters of our imaging devices (scan converter, frame grabber, and video camera), as well as the geometric transformations that relate all of t he physical objects of the system to a known world coordinate system.