First-Person Locomotion in 3D Virtual Environments: a Usability Analysis

3D Virtual Environments (VE) are becoming popular as a tool for cognitive, functional and psychological assessment. Navigation in these environments is recognized as one of the most difficult activities in 3D Virtual Environments (VE). Users unfamiliar to 3D games, specially elder persons, get puzzled when they try to virtually move an avatar through these environments. Their inability to navigate prevents them from concentrating in the task and even to finish it. In this paper, we analyze the influence of different factors in locomotion control. We investigate the impact of having the cursor fixed at the camera center or leaving it free inside the current view. We also analyze the influence of the pitch angle on the camera control. In addition, we have designed an automatic locomotion system that we compare to user-controlled locomotion. We describe a virtual scenario and a test task that we have implemented to evaluate these different methods with users of diverse profiles. We conclude that, for non-casual gamers, automatic locomotion is the faster and preferred mode, whereas gamers prefer to control locomotion themselves. For nonautomatic locomotion, the performance is better when the cursor is fixed in the view center point during locomotion. On the contrary, for still positions, a free-cursor is preferable. Finally, restriction of the pitch angle in a solid angle that encompasses the objects related to the task is better than a free pitch angle rotation for still positions. During locomotion, fixing the pitch angle at the horizontal level enhances the locomotion.