Effects of User Perspective, Visual Context, and Feedback on Interactions with AR targets on Magic-lens Displays.

Performing tasks in a close range using augmented content or instructions visualized on a 2D display can be difficult because of missing visual information in the third dimension. This is because the world on the screen is rendered from the perspective of a single camera, typically on the device itself. However, when performing tasks using hands, haptic feedback supports vision, and prior knowledge and visual context affect task performance. This study rendered the world on a display from the user's perspective to re-enable depth cues from motion parallax and compared it with the conventional device perspective during haptic interactions. We conducted a user study involving 20 subjects and two experiments. First, the accuracy of touchpoint and depth estimation was measured under the conditions of a visual context and perspective rendering on a magic-lens display. We found that user-perspective rendering slightly improved the touch accuracy of targets on a physical surface; however, it significantly improved interactions without tactile feedback. This effect is relatively large when contextual information from the environment is absent, and it diminishes with increased haptic interactions. In the second experiment, we used a user-perspective magic lens to validate the proposed method in a practical needle injection scenario and confirm that the initial injections to virtual targets were more accurate. The results indicate that user-perspective rendering on magic lenses improves immediate performance in haptic tasks, suggesting they are particularly advantageous for frequently changing environments or short-duration tasks.