Playing with Delay: an Interactive VR Demonstration

Playing with delay: An interactive VR demonstration Kjetil Raaen Ragnhild Eg Ivar Kjellmo [email protected] [email protected] [email protected] Kristiania Universiy College Kristiania Universiy College Kristiania Universiy College Oslo, Norway Oslo, Norway Oslo, Norway Figure 1: This demo invites participants to play squash in Virtual Reality, and to explore the feel and eect of delay. ABSTRACT ACM Reference Format: Virtual reality is now used across a range of applications, from Kjetil Raaen, Ragnhild Eg, and Ivar Kjellmo. 2019. Playing with delay: An interactive VR demonstration. In entertainment to clinical purposes. Although the rendered visu- 11th International Workshop on Immer- sive Mixed and Virtual Environment Systems (MMVE ’19), June 21, 2019, alisations have better temporal and spatial resolutions than ever, Amherst, MA, USA. ACM, New York, NY, USA, 3 pages. https://doi.org/10. several technological constraints remain – and people still suer 1145/3304113.3326114 side-eects. With this demonstration, we address the temporal constraints of virtual reality. We invite participants to play a game where they are in charge of the presented delay, facilitating their 1 INTRODUCTION AND BACKGROUND rst-hand experience of the consequences of delay. Furthermore, Virtual Reality (from now on VR) often refers to the use of stereo- the demonstration serves as a platform for future explorations into scopic head mounted displays (HMD) that cover the entire eld of short- and long-term eects of virtual reality constraints. view, where the view tracks the user’s head motion. This creates an extremely immersive experience. However, to achieve high quality CCS CONCEPTS of experience, the technical requirements are high. The experience also needs to be well designed to avoid discomfort. One important • → ; Human-centered computing Virtual reality Empirical contributor to discomfort is delay. If you turn your head, and the . studies in HCI world follows later, the world will feel unstable [1]. There is lim- ited research on exactly what is considered fast enough tracking, KEYWORDS but one study points to a limit somewhere between 180 ms and virtual reality, perception, cyber sickness, delay, game 220 ms [1]. (Note that this number is often cited as 50-90 ms. Such a reading ignores the reported inherent latency in the tested system of 122 ms [1].) This contrasts sharply with best practices in the commercial industry, where recommendations are a maximum of Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed 20 ms latency [13], though without citations or apparent empirical for prot or commercial advantage and that copies bear this notice and the full citation data. Resolving this discrepancy will require systematic qualitative on the rst page. Copyrights for components of this work owned by others than the and quantitative studies using modern equipment. author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specic permission This demonstration is the rst step towards mapping out the and/or a fee. Request permissions from [email protected]. constraints of VR technology, and the subjective consequences MMVE ’19, June 21, 2019, Amherst, MA, USA of delayed VR interactions. In a game environment that can be © 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM. ACM ISBN 978-1-4503-6299-3/19/06...$15.00 used as a test platform for future experiments on VR interactions, https://doi.org/10.1145/3304113.3326114 we allow participants to experience the perceptual, and possibly MMVE ’19, June 21, 2019, Amherst, MA, USA K. Raaen, R. Eg, I. Kjellmo physical, consequences of delays in virtual reality. The purpose of correspondence between displays, controllers and audio devices. this demonstration is to gather feedback on the experience and the Moreover, sensorimotor adaptation follows interactions between methodology, laying the ground for future studies on the eects of physical movements, typically head and hand movements, and delay and possibly other technical factors that may inuence the corresponding virtual actions. This type of sensory adaptation is quality of VR experiences. vulnerable to spatial and temporal artefacts, particularly when it comes to inertial cues [19]. 1.1 Challenges The industry has come a long way in rening spatial and temporal 1.3 Individual dierences parameters in VR. Earlier works show that the Oculus Rift allows Motion sickness and simulator sickness have more than symptoms minimum latencies below 10 ms [15], and the upper bound for HTC in common. They both vary in occurrence and severity across indi- Vive is estimated at 22 ms [12]. According to specications from viduals. It seems some tolerate virtual sensations better than others, the manufacturers1 [13], both the HTC Vive and the Oculus Rift just like some can go from one ride to the next in an amusement sport 110° eld-of-view, 90 Hz refresh rate, and a binocular total of park. These individual dierences have also been noted for other VR 2160x1200 pixel resolution. Although the industry has come a long experiences, such as navigation, task performance, and information way, many solutions are established without transparency. That is, organisation [17]. Others have touched upon the background of par- manufacturers have insight about the limitations and requirements ticipants and stressed the importance of understanding individual of their technology, but this insight is not necessarily available to characteristics, ranging from spatial understanding and memory to researchers. Furthermore, some challenges are only moderated, and motor and verbal skills, even gender and personality [4, 11, 17]. Yet new ones are discovered along the way. VR set-ups like Oculus Rift we still lack a comprehensive understanding of the characteristics and HTC Vive come with high temporal resolutions and minimal that aect both simulator sickness and usability factors, and how delays in motion tracking, which has alleviated associated conse- experience and adaptation can serve as mediators [3]. quences, but certainly not removed them. The applications that run in VR require additional processing capacities, and the demands 2 DEMONSTRATION SETUP increase as applications become more advanced. Furthermore, new This demonstration introduces a VR environment with direct con- interaction modes introduce new challenges, such as tracking limi- trol over the motion tracking delay. The environment itself is a tations in VR controllers, uncovered by a team at Valve software. simple VR game running on state-of-the-art VR equipment. Par- Apparently, some players exhibit preterhuman-like capabilities in ticipants play single player squash, shown in gure 1, attempting icking their wrists [14]. to keep the ball in play. With direct control over delays in the VR Other past challenges that remain unsolved include spatial reso- scene, participants can experience rst-hand the consequences of lution, ickering, mis-matches between physical and visual motion a fully immersive virtual environment that gradually moves away (vection/optical ow), and mis-representations of depth cues or from a familiar physical law. elds of view [4, 5, 10, 13]. Along with temporal resolution and delays, these are well-studied causes for simulator sickness. 2.1 Equipment 2 1.2 Side eects and usability The game is developed in the Unity game engine using the Open VR framework3. In terms of content, we present players with a So-called simulator sickness, or cyber sickness, bears many simi- realistic rendering of a squash court. The hand-held controller is larities to motion sickness. They are both attributed to the discor- displayed in the game as a racket, tracking the user’s hand. Using dance between visual and vestibular signals, and they share symp- the option for room-scale VR, participants are free to move around toms [7], including nausea, disorientation, sweating and oculomotor the court to hit the ball. Movement of the ball is simulated using symptoms such as dizziness, vertigo and visual disturbances [9, 16]. approximations of real physics. Among these, nausea-related symptoms are typically the ones re- For VR display and interactions we use Vive Pro4. The system ported by participants who need to abandon an experiment [2]. used for running the game has yet to be decided, but we will make Sickness is not the only side eect that follows the technical sure to use hardware that introduces as little delay as possible. With limitations that still aect VR technology. The virtual experience the tested setup5, this VR game has a an average delay of 38 ms itself is shaped by restrictions posed by the technology that pro- before we add any experimental delay, as measured using the setup duces, conveys and renders the VR environment, from graphics, described in Raaen and Kjellmo[15]. design and layout to sounds and tactile feedback. The somewhat undened notion of immersion is dependent on the visual world 2.2 Demonstration that unfolds in VR [8], but also on other sensory experiences. For The demonstration invites participants to rst explore the virtual en- instance, real locomotion is a usability issue that researchers are vironment, and the game itself. When they have become acquainted addressing, aiming to tip the immersion scale [18]. Captivating with the

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