It is difficult to interact with computer displays that are across the room. A popular approach is to use laser pointers tracked by a camera, but interaction techniques using laser pointers tend to be imprecise, error-prone, and slow. Although many previous papers discuss laser pointer interaction techniques, none seem to have performed user studies to help inform the design. This paper reports on two studies of laser pointer interactions that answer some of the questions related to interacting with objects using a laser pointer. The first experiment evaluates various parameters of laser pointers. For example, the time to acquire a target is about 1 second, and the jitter due to hand unsteadiness is about ±8 pixels, which can be reduced to about ±2 to ±4 pixels by filtering. We compared 7 different ways to hold various kinds of laser pointers, and found that a laser pointer built into a PalmOS device was the most stable. The second experiment compared 4 different ways to select objects on a large projected display. We found that tapping directly on a wall-size SmartBoard was the fastest and most accurate method, followed by a new interaction technique that copies the area of interest from the big screen to a handheld. Third in speed was the conventional mouse, and the laser pointer came in last, with a time almost twice as long as tapping on the SmartBoard

We describe our system which facilitates collaboration using multiple modalities, including speech, handwriting, gestures, gaze tracking, direct manipulation, large projected touch-sensitive displays, laser pointer tracking, regular monitors with a mouse and keyboard, and wireless networked handhelds. Our system allows multiple, geographically dispersed participants to simultaneously and flexibly mix different modalities using the right interface at the right time on one or more machines. We discuss each of the modalities provided, how they were integrated in the system architecture, and how the user interface enabled one or more people to flexibly use one or more devices.