Usability of multiviewpoint images for spatial interaction in projection-based display systems.

In a common application scenario, large screen projection-based stereoscopic display systems are not used by a single user alone, but are shared by a small group of people. Using multiviewpoint images for multiuser interaction does not require special hardware and scales transparently with the number of colocated users in a system. We present a qualitative and quantitative study comparing usability and interaction performance for multiviewpoint images to non-head-tracked and head-tracked interaction for ray-casting selection and in-hand object manipulation. Results show that while direct first-person interaction in projection-based displays without head-tracking is difficult or even completely impractical, interaction with multiviewpoint images can produce similar or even better performance than fully head-tracked interaction. For ray-casting selection, interaction with multiviewpoint images is actually up to 10 percent faster than head-tracked interaction. For in-hand object manipulation in a simple docking task, multiviewpoint interaction performs only about 6 percent slower than fully head-tracked interaction.