Target Acquisition with Camera Phones when used as Magic Lenses

When camera phones are used as magic lenses in handheld augmented reality applications involving wall maps or posters, pointing can be divided into two phases: (1) an initial coarse physical pointing phase, in which the target can be directly observed on the background surface, and (2) a fine-control virtual pointing phase, in which the target can only be observed through the device display. In two studies, we show that performance cannot be adequately modeled with standard Fitts' law, but can be adequately modeled with a two-component modification. We chart the performance space and analyze users' target acquisition strategies in varying conditions. Moreover, we show that the standard Fitts' law model does hold for dynamic peephole pointing where there is no guiding background surface and hence the physical pointing component of the extended model is not needed. Finally, implications for the design of magic lens interfaces are considered.