Virtual Object Grasping in Augmented Reality: Drop Shadows for Improved Interaction

This paper presents the use of rendered visual cues as drop shadows and their impact on overall usability and accuracy of grasping interactions for Augmented Reality (AR). We report on two conditions; grasping with drop shadows and without drop shadows and analyse a total of 910 grasps. We report on the accuracy of Grasp Aperture (GAp), Grasp Displacement (GDisp), completion time and usability metrics from 30 participants. A comprehensive statistical analysis of the results is presented giving comparisons of the inclusion of drop shadows in AR grasping. Findings showed that the use of drop shadows increases usability of AR grasping while significantly decreasing task completion time. Furthermore drop shadows also significantly improve user's depth estimation of AR object position. However, this study also shows that using drop shadows does not improve user's object size estimation, which remains as a problematic element in grasping AR interaction literature.