A wall-sized display covers a large portion of a wall, typically by tiling images created by multiple projectors. For instance, one display at the University of Kansas measures 25 x 6 feet, covers 120 of the visual field, and provides a 5,760 x 1,200 pixel resolution (Color Plate 25.2). As with desktop displays, wall-sized displays can often be viewed without any special devices (e.g., the head tracker and eyeglasses mentioned later for the CAVE). Although a traditional keyboard and mouse can be used to interact with a wall-sized display, other control devices either are being used or are in the process of being developed. For instance, Guimbretiere et al. (2001) and Davis and Chen (2002) described pen- based and laser pointer approaches, respectively. Such novel control devices are essential, given the varied distances of users from the display and the need to handle simultaneous users. An overview of technical issues associated with wall-sized displays (e.g., combining images from multiple projectors) can be found in the July/August 2000 issue of IEEE Computer Graphics and Applications