Rendering for Head Mounted Displays (HMD) causes a doubled computational effort, since serving the human stereopsis requires the creation of one image for the left and one for the right eye. The difference in this image pair, called binocular disparity, is an important cue for depth perception and the spatial arrangement of surrounding objects. Findings in the context of the human visual system (HVS) have shown that especially in the near range of an observer, binocular disparities have a high significance. But as with rising distance the disparity converges to a simple geometric shift, also the importance as depth cue exponentially declines. In this paper, we exploit this knowledge about the human perception by rendering objects fully stereoscopic only up to a chosen distance and monoscopic, from there on. By doing so, we obtain three distinct images which are synthesized to a new hybrid stereoscopic image pair, which reasonably approximates a conventionally rendered stereoscopic image pair. The method has the potential to reduce the amount of rendered primitives easily to nearly 50 % and thus, significantly lower frame times. Besides of a detailed analysis of the introduced formal error and how to deal with occurring artifacts, we evaluated the perceived quality of the VR experience during a comprehensive user study with nearly 50 participants. The results show that the perceived difference in quality between the shown image pairs was generally small. An in-depth analysis is given on how the participants reached their decisions and how they subjectively rated their VR experience.

Interactive user interfaces in head-mounted Augmented Reality environments are not always projected onto a physical surface. However, operating such free-floating interfaces by touch gestures is challenging because they do not provide haptic feedback. Considering a pointing gesture, in this work we present a user study evaluating the benefits of increasing the arm position sense for operating non-haptic interface. Our findings confirm that haptic feedback is required and show that an increased arm sense compensates for the lack of haptic feedback. The results suggest that applying 0.3 times of the pointing arm’s weight significantly speeds up direct object selection for free-floating interfaces. We also show that the correction phase of the underlying pointing movement is affected by boosting the arm sense.

The performance of Augmented Reality (AR) direct object selection coded outside of the human egocentric body frame of reference is decreased under short-term altered gravity. Therefore an adequate countermeasure is required. This paper presents the results of a proof-of-concept (POC) study to investigate the impact of simulated hypergravity on target's size and distance. For gravity-dependent resizing and -positioning we used Hooke's law for the target deformation. The POC study was divided in two experiments, whereby hypergravity was induced by a long-arm human centrifuge and by weights attached to subjects' dominant arm. The study showed that at higher gravity levels larger target size and larger distance between the targets led to increased performance.

We present our current state in developing and testing of Augmented Reality supported spaceflight procedures for intra-vehicular payload activities. Our vision is to support the ground team and the flight crew to author and operate easily AR guidelines without programming and AR knowledge. For visualization of the procedural instructions using an HMD, 3D registered visual aids are overlaid onto the payload model operated by additional voice control. Embedded informational resources (e.g., images and videos) are provided through a mobile tangible user interface. In a pilot study that was performed at the ESA European Astronaut Centre by application domain experts, we evaluated the performance, workload and acceptance by comparing our AR system with the conventional method of displaying PDF documents of the procedure.