Audio, visual, and audio-visual egocentric distance perception by moving participants in virtual environments

International audienceA study on audio, visual, and audio-visual egocentric distance perception by moving participants in virtual environments is presented. Audio-visual rendering is provided using tracked passive visual stereoscopy and acoustic wave fi eld synthesis (WFS). Distances are estimated using indirect blind-walking (triangulation) under each rendering condition. Experimental results show that distances perceived in the virtual environment are accurately estimated or overestimated for rendered distances closer than the position of the audio-visual rendering system and underestimated for distances farther. Interestingly, participants perceived each virtual object at a modality-independent distance when using the audio modality, the visual modality, or the combination of both. Results show WFS capable of synthesizing perceptually meaningful sound fields in terms of distance. Dynamic audio-visual cues were used by participants when estimating the distances in the virtual world. Moving may have provided participants with a better visual distance perception of close distances than if they were static. No correlation between the feeling of presence and the visual distance underestimation has been found. To explain the observed perceptual distance compression, it is proposed that, due to con flicting distance cues, the audio-visual rendering system physically anchors the virtual world to the real world. Virtual objects are thus attracted by the physical audio-visual rendering system

Audio, visual, and audio-visual egocentric distance perception in virtual environments.

International audiencePrevious studies have shown that in real environments, distances are visually correctly estimated. In visual (V) virtual environments (VEs), distances are systematically underestimated. In audio (A) real and virtual environments, near distances (2 m) are underestimated. However, little is known regarding combined A and V interactions on the egocentric distance perception in VEs. In this paper we present a study of A, V, and AV egocentric distance perception in VEs. AV rendering is provided via the SMART-I2 platform using tracked passive visual stereoscopy and acoustical wave field synthesis (WFS). Distances are estimated using triangulated blind walking under A, V, and AV conditions. Distance compressions similar to those found in previous studies are observed under each rendering condition. The audio and visual modalities appears to be of similar precision for distance estimations in virtual environments. This casts doubts on the commonly accepted visual capture theory in distance perception

Perceptual Requirements for World-Locked Rendering in AR and VR

Stereoscopic, head-tracked display systems can show users realistic, world-locked virtual objects and environments. However, discrepancies between the rendering pipeline and physical viewing conditions can lead to perceived instability in the rendered content resulting in reduced realism, immersion, and, potentially, visually-induced motion sickness. The requirements to achieve perceptually stable world-locked rendering are unknown due to the challenge of constructing a wide field of view, distortion-free display with highly accurate head- and eye-tracking. In this work we introduce new hardware and software built upon recently introduced hardware and present a system capable of rendering virtual objects over real-world references without perceivable drift under such constraints. The platform is used to study acceptable errors in render camera position for world-locked rendering in augmented and virtual reality scenarios, where we find an order of magnitude difference in perceptual sensitivity between them. We conclude by comparing study results with an analytic model which examines changes to apparent depth and visual heading in response to camera displacement errors. We identify visual heading as an important consideration for world-locked rendering alongside depth errors from incorrect disparity

Shaping the auditory peripersonal space with motor planning in immersive virtual reality

Immersive audio technologies require personalized binaural synthesis through headphones to provide perceptually plausible virtual and augmented reality (VR/AR) simulations. We introduce and apply for the first time in VR contexts the quantitative measure called premotor reaction time (pmRT) for characterizing sonic interactions between humans and the technology through motor planning. In the proposed basic virtual acoustic scenario, listeners are asked to react to a virtual sound approaching from different directions and stopping at different distances within their peripersonal space (PPS). PPS is highly sensitive to embodied and environmentally situated interactions, anticipating the motor system activation for a prompt preparation for action. Since immersive VR applications benefit from spatial interactions, modeling the PPS around the listeners is crucial to reveal individual behaviors and performances. Our methodology centered around the pmRT is able to provide a compact description and approximation of the spatiotemporal PPS processing and boundaries around the head by replicating several well-known neurophysiological phenomena related to PPS, such as auditory asymmetry, front/back calibration and confusion, and ellipsoidal action fields

Optimizing vision and visuals: lectures on cameras, displays and perception

The evolution of the internet is underway, where immersive virtual 3D environments (commonly known as metaverse or telelife) will replace flat 2D interfaces. Crucial ingredients in this transformation are next-generation displays and cameras representing genuinely 3D visuals while meeting the human visual system's perceptual requirements. This course will provide a fast-paced introduction to optimization methods for next-generation interfaces geared towards immersive virtual 3D environments. Firstly, we will introduce lensless cameras for high dimensional compressive sensing (e.g., single exposure capture to a video or one-shot 3D). Our audience will learn to process images from a lensless camera at the end. Secondly, we introduce holographic displays as a potential candidate for next-generation displays. By the end of this course, you will learn to create your 3D images that can be viewed using a standard holographic display. Lastly, we will introduce perceptual guidance that could be an integral part of the optimization routines of displays and cameras. Our audience will gather experience in integrating perception to display and camera optimizations. This course targets a wide range of audiences, from domain experts to newcomers. To do so, examples from this course will be based on our in-house toolkit to be replicable for future use. The course material will provide example codes and a broad survey with crucial information on cameras, displays and perception

A multi-projector CAVE system with commodity hardware and gesture-based interaction

Spatially-immersive systems such as CAVEs provide users with surrounding worlds by projecting 3D models on multiple screens around the viewer. Compared to alternative immersive systems such as HMDs, CAVE systems are a powerful tool for collaborative inspection of virtual environments due to better use of peripheral vision, less sensitivity to tracking errors, and higher communication possibilities among users. Unfortunately, traditional CAVE setups require sophisticated equipment including stereo-ready projectors and tracking systems with high acquisition and maintenance costs. In this paper we present the design and construction of a passive-stereo, four-wall CAVE system based on commodity hardware. Our system works with any mix of a wide range of projector models that can be replaced independently at any time, and achieves high resolution and brightness at a minimum cost. The key ingredients of our CAVE are a self-calibration approach that guarantees continuity across the screen, as well as a gesture-based interaction approach based on a clever combination of skeletal data from multiple Kinect sensors.Preprin

Sonic Interactions in Virtual Environments: the Egocentric Audio Perspective of the Digital Twin

The relationships between the listener, physical world and virtual environment (VE) should not only inspire the design of natural multimodal interfaces but should be discovered to make sense of the mediating action of VR technologies. This chapter aims to transform an archipelago of studies related to sonic interactions in virtual environments (SIVE) into a research field equipped with a first theoretical framework with an inclusive vision of the challenges to come: the egocentric perspective of the auditory digital twin. In a VE with immersive audio technologies implemented, the role of VR simulations must be enacted by a participatory exploration of sense-making in a network of human and non-human agents, called actors. The guardian of such locus of agency is the auditory digital twin that fosters intra-actions between humans and technology, dynamically and fluidly redefining all those configurations that are crucial for an immersive and coherent experience. The idea of entanglement theory is here mainly declined in an egocentric-spatial perspective related to emerging knowledge of the listener's perceptual capabilities. This is an actively transformative relation with the digital twin potentials to create movement, transparency, and provocative activities in VEs. The chapter contains an original theoretical perspective complemented by several bibliographical references and links to the other book chapters that have contributed significantly to the proposal presented here.Comment: 46 pages, 5 figures. Pre-print version of the introduction to the book "Sonic Interactions in Virtual Environments" in press for Springer's Human-Computer Interaction Series, Open Access license. The pre-print editors' copy of the book can be found at https://vbn.aau.dk/en/publications/sonic-interactions-in-virtual-environments - full book info: https://sive.create.aau.dk/index.php/sivebook

Inattentional Blindness for Redirected Walking Using Dynamic Foveated Rendering

Redirected walking is a Virtual Reality(VR) locomotion technique which enables users to navigate virtual environments (VEs) that are spatially larger than the available physical tracked space. In this work we present a novel technique for redirected walking in VR based on the psychological phenomenon of inattentional blindness. Based on the user's visual fixation points we divide the user's view into zones. Spatially-varying rotations are applied according to the zone's importance and are rendered using foveated rendering. Our technique is real-time and applicable to small and large physical spaces. Furthermore, the proposed technique does not require the use of stimulated saccades but rather takes advantage of naturally occurring saccades and blinks for a complete refresh of the framebuffer. We performed extensive testing and present the analysis of the results of three user studies conducted for the evaluation