Locomotion Mechanics in Virtual Reality

Cover Image:  https://assets.wired.com/photos/w_1720/wp-content/uploads/2016/10/RoboRecall_TA.jpg

 

As Virtual Reality (VR) is becoming increasingly popular, the next step is to develop and perfect locomotion systems that eliminate the current issue of simulator sickness.  A major contributor to simulator sickness is vection, which HTC believes it can solve through real-world movement and the implementation of the Valve’s Lighthouse tracking and Cloudheads Blink mechanic.  The implementation of the teleportation locomotion mechanic also reduces the presence of vection as seen in games like Robo Recall and Doom VR.

Vection, being the ‘illusory perception of self-motion’ (Oculus, 2016), is the effect created when the users eyes and ears send ‘conflicting signals’ to the users brain resulting in simulator sickness (Unity Technologies, 2016). These signals are sent when the user’s avatar moves throughout a virtual environment while the user body remains in a stationary state (Oculus, 2016).   While Oculus focuses on providing VR experiences through artificial locomotion, allowing users to move throughout an environment through the use of gamepads or controllers while standing or sitting, HTC claims that ‘real-world movement is the best option for VR’ (Martindale, 2016). The HTC Vive in conjunction with Valve’s Lighthouse tracking system aims to provide users with the freedom to ‘explore both physical and virtual spaces’ (James, 2015) through their room scale tracking (Martindale, 2016).

As VR use is constrained by the user’s physical world space, solutions must be developed to allow users to move around in ‘a virtual space with boundaries beyond the physical environment’ (James, 2015).  The lighthouse tracking system works by ‘flooding a room with non-visible light’ to determine the position of tracking devices in 3D space (Buckley, 2015). Through the use of ‘area-sweeping lasers’ (Lang, 2016), the HTC Vive headset and controllers can be tracked throughout a physical space (Lang, 2016).  The lasers, sweeping both horizontally and vertically in the space, integrate data from sensors on the headset and controllers to ‘determine the rotation of the devices and position in 3D space’ with a ‘virtually imperceptible’ jitter of about 0.3mm (Lang, 2016).

Even with the implementation of room scale tracking, additional mechanics may need to be implemented in order to traverse virtual environments when users have play space restrictions.  Cloudhead Games, a Vancouver Island based developer, has introduced a Blink VR locomotion mechanic that enables users to ‘move through a dynamically scaling virtual space without feeling motion sickness’ (Cloudhead Games, 2016) (Game Press, 2016).

Blink mechanisms employ a ‘point, click and teleport system’ that solves the problem of movement throughout a virtual environment by instantaneously moving the user’s avatar to a position and orientation defined by the user (James, 2015).  This movement is accompanied by either fade to black transitions or the more complex blink transitions which simulates the action of blinking (Unity Technologies, 2016).  While employing the blink mechanic, it is imperative to maintain head tracking while fading in and out, or if using the blink transitions if you can match the speed of a human blink the user will stop seeing it (Oculus, 2014).

Cloudhead Games Blink mechanic offers three locomotion features, Cinematic Blink, Precision Blink, and Volume Blink, in addition to Volume Persistence and an Elastic Playspace system (Cloudhead Games, 2016).  Cinematic Blink allows the user to be teleported in the direction that they are looking, Precision Blink provides users with the ability to cast a blink point to a precise location, and Volume Blink allows users to ‘move and rotate their Roomscale volume to strategically maximise the functionality of their playspace’ (Cloudhead Games, 2016).  In addition, Volume Persistence provides users with ‘tangible references’ to their physical play space to encourage safe physical movement, and the Elastic Playspace system scales to the user’s physical playspace regardless of the size of the area (Cloudhead Games, 2016).

Virtual Reality games that employ the blink and teleportation mechanics include Epic Games’ Robo Recall, formerly the Bullet Train demo, and the Doom VR demo by Bethesda. The three games all utilise the Precision Blink mechanism that allows users to pin point the location which they want to teleport to (Cloudhead Games, 2016). Bullet Train and Robo Recall employ the blink mechanism and rely on teleportation as the methods to navigate the environments, utilising a fade-to-white effect which reduce the chance of motion sickness (Volpe, 2015).   The use of the Oculus Touch controllers allow users to set the direction they will face upon teleportation through the rotation of the controller’s left stick (Land, 2016).  The teleportation mechanism throughout Bullet Train and Robo Recall allow users to experience a ‘new level of mobility and interaction’ in the game environment (Nafarrete, 2015), allowing users to tactically teleport around enemies, or move to higher ground to gain an upper hand when fighting opponents (Kohler, 2016).

Doom VR also implements the handheld controllers to initiate teleportation, however in contrast to using Robo Recall’s fade-to-white technique, the world of Doom VR slows down when the user chooses where to teleport and then rushes past as the users is moved to the selected destination (Butterworth, 2016).  As the game does not implement a fade or blink transition, yet pushes the player from ‘slowed down bullet time’ to ‘breakneck speeds’ with remarkable fluidity (Khan, 2016), users do not lose their orientation throughout the process making it easy to continue gameplay immediately after teleportation (Gieselmann, 2016).  Another similarity both Doom VR and Epic Game’s VR creations share is the ability to wield a weapon while being able to initiate teleportation (Ingenito, 2016).

In conclusion, the implementation of a teleportation mechanic, with blink mechanisms employed, used in conjunction with HTC Vive hardware and Valve’s Lighthouse tracking system allow for the creation of a virtual reality game that greatly reduces the effect of vection providing users with an experience that does not ’cause motion sickness.

 

REFERENCES

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Butterworth, S. (2016) Doom May Have Solved VR’s Traversal Problem. Available at: http://www.gamespot.com/articles/doom-may-have-solved-vrs-traversal-problem/1100-6442439/ (Accessed: 12 December 2016).

Cloudhead Games (2016) VR Navigation. Available at: http://cloudheadgames.com/cloudhead/vr-navigation/ (Accessed: 11 December 2016).

Game Press (2016) Cloudhead games’ blink Locomotion technology makes VR nausea obsolete. Available at: http://www.develop-online.net/press-releases/cloudhead-games-blink-locomotion-technology-makes-vr-nausea-obsolete/0209954 (Accessed: 11 December 2016).

Gieselmann, H. (2016) Doom VR umgeht Simulatorkrankheit per Speed-Teleporting. Available at: https://www.heise.de/newsticker/meldung/Doom-VR-umgeht-Simulatorkrankheit-per-Speed-Teleporting-3300087.html (Accessed: 21 December 2016).

Ingenito, V. (2016) QuakeCon 2016: Movement takes doom VR to A new level. Available at: http://au.ign.com/articles/2016/08/04/quakecon-2016-movement-takes-doom-vr-to-a-new-level (Accessed: 21 December 2016).

James, P. (2015a) Cloudhead games’ ‘blink’ to bring nausea-free VR to HTC Vive this holiday. Available at: http://www.roadtovr.com/cloudhead-games-blink-to-debut-nausea-free-vr-on-htc-vive-this-holiday/ (Accessed: 11 December 2016).

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Khan, A. (2016) Doom VR Impressions: Teleport Strafing Behind the Back Like a Boss. Available at: http://www.shacknews.com/article/96187/doom-vr-impressions-teleport-strafing-behind-the-back-like-a-boss (Accessed: 21 December 2016).

Kohler, C. (2016) Epic’s VR Shooter Bullet Train Is Now the Wacky Robo Recall. Available at: https://www.wired.com/2016/10/epic-robo-recall-bullet-train/ (Accessed: 21 December 2016).

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Lang, B. (2016) Hands-on: Epic’s new action-packed ‘Robo recall’ FPS is beautiful, brutal arcade fun. Available at: http://www.roadtovr.com/epic-games-robo-recall-vr-oculus-touch-hands-on/ (Accessed: 21 December 2016).

Martindale, J. (2016) How should we move around in VR? Nobody has figured it out yet. Available at: http://www.digitaltrends.com/virtual-reality/vr-locomotion-movement-omni-hover-junkers/ (Accessed: 11 December 2016).

Nafarrete, J. (2015) ‘Bullet train’ made me believe I was A Superhero. Available at: http://vrscout.com/news/bullet-train-oculus-touch/ (Accessed: 21 December 2016).

Oculus (2014) Connect: Developing VR experiences with the Oculus rift. Available at: https://www.youtube.com/watch?v=addUnJpjjv4&feature=youtu.be&t=40m5s (Accessed: 12 December 2016).

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Volpe, J. (2015) Epic games’ new shooter is Oculus rift’s killer virtual reality gaming app. Available at: https://www.engadget.com/2015/09/25/epic-games-new-shooter-is-virtual-reality-killer-gaming-app/ (Accessed: 12 December 2016).

Unity Technologies (2016) Movement in VR. Available at: https://unity3d.com/learn/tutorials/topics/virtual-reality/movement-vr (Accessed: 11 December 2016).

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