Propping Up Virtual Reality With Haptic Proxies.

Physical props serving as proxies for virtual objects (haptic proxies) offer a cheap, convenient, and compelling way of delivering a sense of touch in virtual reality (VR). To successfully use haptic proxies for VR, they have to be both similar to and colocated with their virtual counterparts. In this article, we introduce a taxonomy organizing techniques using haptic proxies for VR into eight categories based on when the techniques are deployed (offline or real-time), what reality is being manipulated (physical or virtual reality), and the purpose of the techniques (to affect object perception or the mapping between real and virtual objects). Finally, we discuss key advantages and limitations of the different categories of techniques.

Superhuman Hearing - Virtual Prototyping of Artificial Hearing: a Case Study on Interactions and Acoustic Beamforming.

Directivity and gain in microphone array systems for hearing aids or hearable devices allow users to acoustically enhance the information of a source of interest. This source is usually positioned directly in front. This feature is called acoustic beamforming. The current study aimed to improve users' interactions with beamforming via a virtual prototyping approach in immersive virtual environments (VEs). Eighteen participants took part in experimental sessions composed of a calibration procedure and a selective auditory attention voice-pairing task. Eight concurrent speakers were placed in an anechoic environment in two virtual reality (VR) scenarios. The scenarios were a purely virtual scenario and a realistic 360° audio-visual recording. Participants were asked to find an individual optimal parameterization for three different virtual beamformers: (i) head-guided, (ii) eye gaze-guided, and (iii) a novel interaction technique called dual beamformer, where head-guided is combined with an additional hand-guided beamformer. None of the participants were able to complete the task without a virtual beamformer (i.e., in normal hearing condition) due to the high complexity introduced by the experimental design. However, participants were able to correctly pair all speakers using all three proposed interaction metaphors. Providing superhuman hearing abilities in the form of a dual acoustic beamformer guided by head and hand movements resulted in statistically significant improvements in terms of pairing time, suggesting the task-relevance of interacting with multiple points of interests.

Auditory Feedback for Navigation with Echoes in Virtual Environments: Training Procedure and Orientation Strategies.

Being able to hear objects in an environment, for example using echolocation, is a challenging task. The main goal of the current work is to use virtual environments (VEs) to train novice users to navigate using echolocation. Previous studies have shown that musicians are able to differentiate sound pulses from reflections. This paper presents design patterns for VE simulators for both training and testing procedures, while classifying users' navigation strategies in the VE. Moreover, the paper presents features that increase users' performance in VEs. We report the findings of two user studies: a pilot test that helped improve the sonic interaction design, and a primary study exposing participants to a spatial orientation task during four conditions which were early reflections (RF), late reverberation (RV), early reflections-reverberation (RR) and visual stimuli (V). The latter study allowed us to identify navigation strategies among the users. Some users (10/26) reported an ability to create spatial cognitive maps during the test with auditory echoes, which may explain why this group performed better than the remaining participants in the RR condition.

Where would you like to eat? A formative evaluation of mixed-reality solitary meals in virtual environments for older adults with mobility impairments who live alone.

This paper reports the results from a formative evaluation of a mixed-reality (MR) eating prototype developed in collaboration with a restaurant for older adults in Holstebro, Denmark. The prototype is used to demonstrate to the older adults the idea of MR eating in two virtual environments. We use qualitative techniques to address the question: What virtual environment do mobility-restricted older Danish adults perceive as engaging and suitable for pleasurable, MR solitary meals? The participants repeatedly used the label "coziness" to describe their desired atmosphere for an eating environment. They critiqued the realism, color scheme and cleanliness of the presented virtual environments. Results from a card-sorting task where participants matched their preferred environments with specific meals, showed that their classifications were based on safety, realism, practicality, social acceptability, time, palatability, and indoor-outdoor considerations.

15 Years of Research on Redirected Walking in Immersive Virtual Environments.

Virtual reality users wearing head-mounted displays can experience the illusion of walking in any direction for infinite distance while, in reality, they are walking a curvilinear path in physical space. This is accomplished by introducing unnoticeable rotations to the virtual environment-a technique called redirected walking. This paper gives an overview of the research that has been performed since redirected walking was first practically demonstrated 15 years ago.

Establishing the range of perceptually natural visual walking speeds for virtual walking-in-place locomotion.

Walking-In-Place (WIP) techniques make it possible to facilitate relatively natural locomotion within immersive virtual environments that are larger than the physical interaction space. However, in order to facilitate natural walking experiences one needs to know how to map steps in place to virtual motion. This paper describes two within-subjects studies performed with the intention of establishing the range of perceptually natural walking speeds for WIP locomotion. In both studies, subjects performed a series of virtual walks while exposed to visual gains (optic flow multipliers) ranging from 1.0 to 3.0. Thus, the slowest speed was equal to an estimate of the subjects normal walking speed, while the highest speed was three times greater. The perceived naturalness of the visual speed was assessed using self-reports. The first study compared four different types of movement, namely, no leg movement, walking on a treadmill, and two forms of gestural input for WIP locomotion. The results suggest that WIP locomotion is accompanied by a perceptual distortion of the speed of optic flow. The second study was performed using a 4×2 factorial design and compared four different display field-of-views (FOVs) and two types of movement, walking on a treadmill and WIP locomotion. The results revealed significant main effects of both movement type and field of view, but no significant interaction between the two variables. Particularly, they suggest that the size of the display FOV is inversely proportional to the degree of underestimation of the virtual speeds for both treadmill-mediated virtual walking and WIP locomotion. Combined, the results constitute a first attempt at establishing a set of guidelines specifying what virtual walking speeds WIP gestures should produce in order to facilitate a natural walking experience.