Abstract. It is difficult to interact with computer displays that are across the room, which can be important in meetings and when controlling computerized devices. 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. Therefore, we have developed a new interaction style, where the laser pointer (or other pointing technique such pointing with a finger or even eye tracking) indicates the region of interest, and then the item there is copied ("snarfed") to the user's handheld device, such as a Palm or PocketPC handheld. If the content changes on the PC, the handheld's copy will be updated as well. Interactions can be performed on the handheld using familiar direct manipulation techniques, and then the modified version is sent back to the PC. The content often must be reformatted to fit the properties of the handheld to facilitate natural interaction.

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.

This paper reports on some fundamental parameters for the design of wall-based laser pointer interaction techniques. Ten users participated in this study and their laser points were tracked and recorded by a computer. The data collected were then processed and statistically analyzed to provide parameters like the size of the dwell of a laser point, the time taken to acquire a target and the time required to determine a dwell on a target. These numbers are needed when designing interaction techniques that use a laser pointer.

We describe our system which facilitates collaboration using multiple modalities, including speech, handwriting, gestures, gaze tracking, direct