The Influence of Gravity-adapted Target Resizing on Direct Augmented Reality Pointing under Simulated Hypergravity.

The performance of Augmented Reality direct object selection coded outside of the human egocentric body frame of reference decreases under short-term altered gravity. Therefore adequate countermeasures are required. This paper presents the results of a proof-of-concept (POC) study to investigate the impact of simulated hypergravity on the size and distance of a given target. The POC study is divided in a case study and a user study, whereby hypergravity was induced by a long-arm human centrifuge and additional arm weighting. For gravity-dependent resizing and –positioning we used the Hooke’s law that resulted in two techniques of target deformation (compression, elongation) and compared both methods with normal sized targets. Besides common metrics to measure the performance, we additionally evaluated the physiological strain by the heart rate variability and the speed-accuracy tradeoff of the resizing techniques according to Fitts’ law. The study showed that the online adaption of the present gravity load to targets' size and distance influences the performance of direct AR direct pointing. The results revealed that the pointing performance benefits from elongation target deformation by increased target sizes and distances.