Empirical Evaluation of Mapping Functions for Navigation in Virtual Reality using Phones with Integrated Sensors

Mobile phones provide an interesting all-in-one alternative for 3D input devices in virtual environments. Mobile phones are becoming touch sensitive and spatially aware, and they are now a crucial part of our daily activities. We present Phone-Based Motion Control, a novel one-handed travel technique for a virtual environment. The technique benefits from the touch capability offered by growing number of mobile phones to change viewpoint translation in virtual environments, while the orientation of the viewpoint is controlled by built-in sensors in the mobile phone. The travel interaction separates translation (touch based translation control) and rotation (steer based rotation control), putting each set of degrees of freedom (DOF) to a separate interaction technique (separability).

This paper examines, how many DOF are needed to perform the travel task as easy and comfortable as possible. It also investigates different mapping functions between the user's actions on the mobile phone and the viewpoint change in the virtual environment. For that purpose, four techniques are implemented: rotate by heading, rotate by roll, rotate by roll with fixed horizon and a merged rotation. Each technique has either 4 or 5 degrees of freedom and different mappings between phone and viewpoint coordinates in the virtual environment. We perform an extensive user study to explore different aspects related to the travel techniques in terms of degrees of freedom, mapping functions. Results of the user evaluation show that 4 DOF techniques seem to perform better the travel task. Even though, the results were not statistically decisive in favor of the usage of the mobile roll to control the viewpoint heading in the virtual environment despite the good results in terms of accuracy and time, there is a clear tendency from the users to prefer the mobile roll as the desired mapping.