Using custom transformation axes for mid-air manipulation of 3D virtual objects

Virtual Reality environments are able to offer natural interaction metaphors. However, it is difficult to accurately place virtual objects in the desired position and orientation using gestures in mid-air. Previous research concluded that the separation of degrees-of-freedom (DOF) can lead to better results, but these benefits come with an increase in time when performing complex tasks, due to the additional number of transformations required. In this work, we assess whether custom transformation axes can be used to achieve the accuracy of DOF separation without sacrificing completion time. For this, we developed a new manipulation technique, MAiOR, which offers translation and rotation separation, supporting both 3-DOF and 1-DOF manipulations, using personalized axes for the latter. Additionally, it also has direct 6-DOF manipulation for coarse transformations, and scaled object translation for increased placement. We compared MAiOR against an exclusively 6-DOF approach and a widget-based approach with explicit DOF separation. Results show that, contrary to previous research suggestions, single DOF manipulations are not appealing to users. Instead, users favored 3-DOF manipulations above all, while keeping translation and rotation independent.