Evaluation of Cursor Offset on 3D Selection in VR

Object selection in a head-mounted display system has been studied extensively. Although most previous work indicates that users perform better when selecting with minimum offset added to the cursor, it is often not possible to directly select objects that are out of arm's reach. Thus, it is not clear whether offset-based techniques will result in improved overall performance. Moreover, due to the difference in muscle requirements of arm and shoulder between a hand-held device and a motion capture device, selection performance may be affected by factors related to ergonomics of the input device. In order to explore these uncertainties, we conduct a user study to evaluate the effects of four virtual cursor offset techniques on 3D object selection performance using Fitts' model and ISO 9241-9 standard while comparing two input devices in a head-mounted display. The results show that selection with No Offset is most efficient when the target is within reach. When the target is out of reach, Linear Offset outperforms Fixed-Length Offset and Go-Go Offset on movement time, error rate and effective throughput, as well as subjective preference evaluation. Overall, the Razer Hydra controller provides better and more stable selection performance than Leap Motion.