Smartphone touch screens are potentially attractive for interaction in virtual reality (VR). However, the user cannot see the phone or their hands in a fully immersive VR setting, impeding their ability for precise touch input. We propose mounting a mirror above the phone screen such that the front-facing camera captures the thumbs on or near the screen. This enables the creation of semi-transparent overlays of thumb shadows and inference of fingertip hover points with deep learning, which help the user aim for targets on the phone. A study compares the effect of visual feedback on touch precision in a controlled task and qualitatively evaluates three example applications demonstrating the potential of the technique. The results show that the enabled style of feedback is effective for thumb-size targets, and that the VR experience can be enriched by using smartphones as VR controllers supporting precise touch input.
The ACM CHI Conference on Human Factors in Computing Systems (https://chi2021.acm.org/)