Estimating and using absolute and relative viewing distance in interactive systems.

In this paper we explore and validate the merits of using absolute and relative viewing distances from the screen as complementary input modalities for interactive systems. We motivate the use of viewing distance as a complementary modality by first mapping out its design space and then proposing several new applications that could benefit from it. We demonstrate that both absolute and relative viewing distance can be reliably estimated under controlled circumstances for both desktop and mobile devices using low-cost cameras and readily available computer vision algorithms. In our evaluations we find that viewing distance is a promising complementary input modality that can be reliably estimated using computer vision in environments with constant lighting. For environments with heterogeneous lighting conditions several challenges still exist when designing practical systems. To aid practitioners and researchers we conclude by highlighting several design implications for future systems.