Effect of Onset Position of Ray Casting in Virtual Reality

Effect of ray casting’s onset positions (i.e., starting position) in virtual reality has been paid little attention. The endpoint of the ray is determined by its onset position; therefore, it can affect users’ pointing and selection process. This paper explores its effects on pointing performance. We conducted a multi-directional tapping task with different onset positions of the ray. Both metrics, endpoint distribution and effective throughput, did not show any universal effects according to the onset position of the ray across 18 participants. However, complex differences for both metrics were found at different onset positions within participants. We found that each participant had an optimal onset position, with an average improvement of 34% in effective throughput. We expect that our findings will enable the establishment of better user interfaces in various 3D interactive systems that employ ray casting techniques.