# The Effects of Augmented Reality Interaction Techniques on Egocentric Distance Estimation Accuracy
## 5 Conclusions  
In this study, the effects of interaction techniques on the interaction performance of accuracy in performing a pointing/selection task within a stereoscopic environment were investigated. The influences of indices of difficulty and different egocentric distances on the accuracy of interaction performance were also examined. The results showed that accuracy in the selection of stereoscopic targets was significantly affected by the interaction technique. Moreover, we also found substantial effects of the distance at which a target was projected at a different level of difficulty within the negative parallax of the stereoscopic display. The indirect cursor technique was more accurate than the direct pointing technique. However, the results also showed that the throughput of the direct cursor technique was higher than that of the indirect cursor technique. This may have been caused by the ease of use and the naturalness of the direct cursor technique allowing faster target selection times, although the means of the task completion times between the direct pointing and indirect cursor techniques were not significantly different. Direct pointing could have interesting implications in VR. The results here suggest that the direct pointing technique may alleviate underestimation of distances in VE, despite the slight overestimation. Consequently, developers of VEs in which user task performance depends on accuracy (for instance, surgical training and simulations) should consider the relative advantages of the direct and indirect interaction techniques. In addition, the experiment revealed that targets displayed at 150 cm from the participant provided the most accurate distance judgment of all three egocentric distances. This result implies that the accuracy of target selection in a stereoscopic environment improves as egocentric distance increases. This result could also be used to enhance the understanding of the effective space during interaction with stereoscopic targets and to propose proper interaction distances with stereoscopic targets and displays. However, future research might be needed to determine how much distance judgment improves with changes in distance by considering targets at farther distances from participants. The present study examined task performance in the frontal plane under three egocentric distance conditions. However, performance in the lateral and transversal planes could be considered in future studies. In addition, the virtual target was displayed in a projection-based stereoscopic environment, and a particular tracking system and input device were employed. Future studies may use different virtual environment systems, such as head-mounted and wide-angle displays, to understand the generalizability of the results. In addition, a simple 3D pointing/selection task is commonly used to determine the effects of interaction techniques on egocentric distance accuracy. However, taking the growing interest in advanced forms of 3D virtual or augmented reality interactions into account, it may be necessary to consider a more complex task to show the performance of the interaction techniques. Therefore, further experimental investigations with a more complex task are recommended to clarify the performance of the interaction techniques. The results reported in this study provide useful information on how accuracy and throughput vary with different interaction (direct and indirect) techniques, levels of egocentric distances, and indices of difficulty in a stereoscopic display. Future studies on interaction in stereoscopic environments might be required to investigate user behaviors and kinematics by evaluating usability and analyzing the movements when different interaction techniques are employed. Conceptualization, C.J.L. and B.H.W. ; methodology, D.C. and B.H.W. ; software, D.C. and B.H.W. ; data collection, D.C.; statistical analysis, D.C.; writing--original draft preparation, D.C.; writing--review and editing, C.J.L. and B.H.W. supervision, C.J.L. and B.H.W.