Virtual vs. Real-World Pointing

We are investigating the utility of a projection-based stereoscopic two-user system for applications in the automotive industry. In this paper we compare real-world pointing to pointing at virtual objects in a two-user scenario. In our study we investigated the following situation: One user points at an object while the second person has to guess the referenced object. Our results indicate that pointing at objects in a virtual world is much less precise than pointing in the real world even for a well calibrated stereoscopic two-user system. Pointing techniques like outlining an object or pointing from a distance produce more errors than the corresponding real-world techniques, but they are less error prone than interactions requiring to touch a virtual object. Our findings are a first step to qualify direct interaction techniques in a multi-user projection-based system.