This article presents the use of rendered visual cues as drop shadows and their impact on overall usability and accuracy of grasping interactions for monitor-based exocentric augmented reality (AR). We report on two conditions, grasping with drop shadows and without drop shadows, and analyze a total of 1620 grasps of two virtual object types (cubes and spheres). We report on the accuracy of one grasp type, the Medium Wrap grasp, against Grasp Aperture ($GAp$GAp), Grasp Displacement ($GDisp$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 times. 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.

中文翻译：

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增强现实中虚拟对象抓取的投影评估

本文介绍了渲染视觉线索作为阴影的使用及其对基于监视器的外中心增强现实 (AR) 的整体可用性和抓取交互准确性的影响。我们报告了两种情况，有阴影和没有阴影的抓取，并分析了两种虚拟对象类型（立方体和球体）的 1620 次抓取。我们报告了一种抓握类型（中等包裹抓握）的准确性，针对抓握孔径（$GAp$GAp）、抓握位移（$GDisp$GDisp）、完成时间和来自 30 名参与者的可用性指标。对结果进行了全面的统计分析，比较了 AR 抓取中包含的阴影。结果表明，阴影的使用增加了 AR 抓取的可用性，同时显着减少了任务完成时间。此外，阴影还显着提高了用户对 AR 对象位置的深度估计。然而，这项研究还表明，使用阴影并不能改善用户对对象大小的估计，这仍然是掌握 AR 交互文献的一个有问题的元素。