Covaci, A

Ghinea, G

Hoermann, S

Lindeman, RW

Wheeler, SG

Brunel University Research Archive

Content-rich and Expansive Virtual Environments Using PassiveProps As World AnchorsSteven G. Wheelersteven.wheeler@pg.canterbury.ac.nzUniversity of CanterburyChristchurch, New ZealandSimon Hoermannsimon.hoermann@canterbury.ac.nzUniversity of CanterburyChristchurch, New ZealandRobert W. Lindemanrob.lindeman@canterbury.ac.nzUniversity of CanterburyChristchurch, New ZealandGeorge Ghineageorge.ghinea@brunel.ac.ukBrunel University LondonLondon, United KingdomAlexandra Covacia.covaci@kent.ac.ukUniversity of KentCanterbury, United KingdomFigure 1: A demonstration of the virtual world translating/rotating to align different virtual and real objects.ABSTRACTIn this paper, we present a system that allows developers to add pas-sive haptic feedback into their virtual reality applications bymakinguse of existing physical objects in the user’s real environment. Ourapproach has minimal dependence on procedural generation anddoes not limit the virtual space to the dimensions of the physicalplay-area.ACM Reference Format:Steven G. Wheeler, Simon Hoermann, Robert W. Lindeman, George Ghinea,and Alexandra Covaci. 2021. Content-rich and Expansive Virtual Environ-ments Using Passive Props As World Anchors. In 27th ACM Symposium onVirtual Reality Software and Technology (VRST ’21), December 8–10, 2021,Osaka, Japan. ACM, New York, NY, USA, 2 pages. https://doi.org/10.1145/3489849.34899471 INTRODUCTIONSince its inception, virtual reality (VR) has been primarily focusedon the visual and aural senses. To enhance the sense of presence ina virtual environment (VE), researchers have since investigated theaddition of touch via passive haptics [1, 2]. However, the creationof physical props to be used in VEs for providing passive haptics isoften an arduous and time-consuming task. This motivated recentresearch to focus on procedural generation of VEs using the user’ssurroundings as a template [4, 5]. While procedural generationremoves the need to make bespoke props, it adds limitations to thePermission to make digital or hard copies of part or all of this work for personal orclassroom use is granted without fee provided that copies are not made or distributedfor profit or commercial advantage and that copies bear this notice and the full citationon the first page. Copyrights for third-party components of this work must be honored.For all other uses, contact the owner/author(s).VRST ’21, December 8–10, 2021, Osaka, Japan© 2021 Copyright held by the owner/author(s).ACM ISBN 978-1-4503-9092-7/21/12.https://doi.org/10.1145/3489849.3489947development of rich, in-depth, story-driven experiences, lendingitself more to the creation of labyrinth-like, random experiences.Furthermore, using the user’s surroundings as a template for VEs,limits the virtual world to the size of the available physical space.We propose a solution for this limitation – Prop-Oriented WorldRotation (POWR) – which aims to assist developers in incorporatingpassive haptics into their VR applications with minimal relianceon procedural generation. While this technique only permits inter-action with a single real/virtual object pairing at any given time,the virtual world is not bound to the size and dimensions of thephysical play space as with related work [4, 5].2 SYSTEM OVERVIEWPOWR consists of a series of scripts that developers can add totheir Unity VR applications. For this, developers must define aset of virtual objects (by applying and configuring the relevantPOWR scripts) that they wish to be physically reinforced by objectsfrom the user’s real environment. Prior to starting the main VRapplication, the user enters a separate VR application – the POWRcalibration room – in which they define the real world objects theywish to be used to physically reinforce virtual objects in the VE.While loading the main application, all virtual objects that havebeen previously designated by the developer to be used by POWRwill be scaled to match the real world counterpart’s size and dimen-sions. Once loaded, a single virtual object (chosen by the developer)is aligned with its real world counterpart by rotating and translat-ing the entire VE (Figure 1). The user may then teleport to otherdesignated points around the VE which, once again, enables POWRto rotate and translate the VE to align a new virtual/real objectpairing.Currently, each designated teleportation point only has a singlereal/virtual object pairing assigned to it thus the user is only able© ACM, YYYY. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in VRST '21: Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology, Article No.: 59, December 2021, https://doi.org/10.1145/3489849.3489947VRST ’21, December 8–10, 2021, Osaka, Japan Wheeler et al.to interact with a single pairing at a time. Furthermore, due toPOWR requiring the real/virtual object pairings’ positions to besynchronized, movement around the VE is limited to physicallymoving around the immediate play-area or teleporting betweenthe designated points.To test the effects on the user’s feeling of safety and level ofpresence with and without POWR, we developed a demonstrationgame. Our game is divided into several areas where we placeddifferent virtual objects the player can use to hide behind whilefighting enemies. The player progresses through the game oncethey shoot all the enemies that are spawned in any given area.When the enemies are defeated, a teleportation point appears and,once players interact with it, the entire level is moved to align anew virtual object with its associated real object.0 50 100 150 200Control Non-ST (APO)POWR Non-ST (APO)POWR STControl ST (No Optimisations)Control ST w/Light BakingControl ST (APO)143.73141.0518.4117.6626.42142.52Average Frames Per SecondFigure 2: Chart of average frames per second of all tests. ST- Stress Test. APO - All Possible Optimisations (as per Unitydocumentation1).3 EFFECT ON PERFORMANCEDue to POWR continuously moving the VE, many objects in theUnity scene cannot be marked as static – a requirement of the Unityengine to apply a number of common performance optimisationssuch as Light Baking or Occlusion Culling. As such, to test thesignificance of lacking such optimizations, we conducted a "stresstest" in which we placed a very computationally demanding objectin the scene and measured the average frame rate with and withoutPOWR. The performance of both demos in the non-stress test scenehad negligible performance differences (Figure 2). However, duringthe stress test, the inclusion of Light Baking in the control demoincreased average frame rate significantly and with the inclusion ofOcclusion Culling performance was on par with the non-stress testscene thereby emphasizing the importance of such optimizations.4 USER STUDYWe conducted a user study where six participants experiencedour demo with and without POWR/passive haptics. In the POWRcondition, users were able to select two real world objects in theirsurroundings for in-game interaction. In the control condition, usersexperienced the game without haptic feedback but used the samedesignated teleportation points as the POWR demo (as opposedto being able to freely teleport anywhere in the scene). The meanage of the participants was 45, and four identified as male andtwo as female. The testing followed a within-subjects design witheach participant testing both conditions, (POWR and control), ina randomised order. Due to the COVID-19 pandemic, the studywas conducted remotely in three separate rooms with three par-ticipants in the first, a single participant in the second and two1"https://learn.unity.com/tutorial/optimizing-your-vr-ar-experiences#5e60ff9cedbc2a002071e0f5"participants in the third; each participant only experienced a singleroom. After completing each experimental condition, participantsfilled in a questionnaire consisting of the validated and widely usedIgroup Presence Questionnaire (IPQ) [3] and a customized safetyquestionnaire.G INV SP REAL−202421.13 1.1−0.531.25 1.7 0.88MedianScoreControl POWRFigure 3: Results of the IPQ Questionnaire – Generic pres-ence (G), Involvement (INV), Spatial Presence (SP), Realism(REAL)Participants reported an enhanced feeling of presence in thePOWR condition which is supported by the IPQ results (Figure 3)where the POWR condition had a higher median score than thecontrol for the generic feeling of “being there”, Spatial Presence andRealism and similar for the attention paid to the VE (Involvement).Regarding the feeling of safety experienced by participants inboth conditions, all but one user answered that they felt “verysafe” in the POWR condition. For the same question, only twoparticipants awarded a maximum score for their feelings of safety inthe control demo. This sentiment was reflected in the user feedbackin which participants expressed a “feeling of trepidation”, with somenoting they felt “afraid to move” despite the protection of the defaultChaperone system.5 CONCLUSIONPOWR is a solid proof of concept which can be applied to VR appli-cations, thereby allowing users to experience haptic feedback. Theuser evaluation was encouraging and the demo was successfullyplayed in three distinct rooms of different sizes and layouts, therebydemonstrating its robustness and versatility. Although POWR’s per-formance in the stress test was less than ideal, with additionaltime, future iterations could work around limitations of the Unityengine and incorporate custom optimisation scripts, such as provid-ing Occlusion Culling, which would significantly improve POWR’sperformance.REFERENCES[1] Ken Hinckley, Randy Pausch, John C. Goble, and Neal F. Kassell. 1994. Passive Real-World Interface Props for Neurosurgical Visualization. In Proceedings of the SIGCHIConference on Human Factors in Computing Systems (Boston, Massachusetts, USA)(CHI ’94). Association for Computing Machinery, New York, NY, USA, 452–458.https://doi.org/10.1145/191666.191821[2] H. G. Hoffman. 1998. Physically touching virtual objects using tactile augmentationenhances the realism of virtual environments. In Proceedings. IEEE 1998 VirtualReality Annual International Symposium (Cat. No.98CB36180). 59–63.[3] Holger Regenbrecht and Thomas Schubert. 2002. Real and illusory interactionsenhance presence in virtual environments. Presence: Teleoperators & Virtual Envi-ronments 11, 4 (2002), 425–434.[4] Adalberto L. Simeone, Eduardo Velloso, and Hans Gellersen. 2015. SubstitutionalReality: Using the Physical Environment to Design Virtual Reality Experiences. InProceedings of the 33rd Annual ACM Conference on Human Factors in ComputingSystems (Seoul, Republic of Korea) (CHI ’15). Association for ComputingMachinery,New York, NY, USA, 3307–3316. https://doi.org/10.1145/2702123.2702389[5] Misha Sra, Sergio Garrido-Jurado, and Pattie Maes. 2017. Oasis: ProcedurallyGenerated Social Virtual Spaces from 3D Scanned Real Spaces. IEEE transactionson visualization and computer graphics 24, 12 (2017), 3174–3187.

Content-rich and Expansive Virtual Environments Using Passive Props As World Anchors

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Content-rich and Expansive Virtual Environments Using Passive Props As World Anchors

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