This slide was presented at SIGGRAPH 2017 Student Research Competition (SRC) finalist presentation. http://s2017.siggraph.org/acm-student-research-competition ReverseCAVE: Providing Reverse Perspectives for Sharing VR Experience https://doi.org/10.1145/3102163.3102208 【Project page】 http://digitalnature.slis.tsukuba.ac.jp/2017/05/reversecave/ 【Project movie】 https://www.youtube.com/watch?v=GUVOxQkkZ_0 【Presenter】 Akira Ishii (石井晃), Masaya Tsuruta (鶴田真也) University of Tsukuba Graduate School of Systems and Information Engineering Master's Program in Computer Science Digital Nature Group (Yoichi Ochiai Lab.) https://akira.io/ https://www.iplab.cs.tsukuba.ac.jp/~tsuruta/ 【Abstract】 Virtual reality (VR) with HMD is closed experience among those who are experiencing the VR, and can only be individually experienced by the specific person. We call this “perspective gap.” These perspective gaps exist in many situations. To address these problems, we present “ReverseCAVE”, a system for sharing the experiences of people in VR with others (observer). As another application, it is possible to visually recognize the actual appearance of the person performing the act at the motion capture studio and the superimposed character at the same time. ReverseCAVE has four translucent screens surrounding the player. VR environment that the player is experiencing is projected onto the screens. By this, the observer can see both the physical player and the VR environment experienced by the player simultaneously. Also, in the motion capture system, when viewing the actor from the observer outside of ReverseCAVE, the character is superimposed to the actor. This makes it look as if the actor is the actual character from the observer. ReverseCAVE enhances the observers’ experience.

1. ReverseCAVE Providing Reverse Perspectives for Sharing VR Experience
Akira Ishii Masaya Tsuruta Ippei Suzuki Shuta Nakamae Tatsuya Minagawa Junichi Suzuki Yoichi Ochiai
U n i v e r s i t y o f Ts u k u b a , Yo i c h i O c h i a i L a b o r a t o r y

3. Awesome SIGGRAPH Experiences

4. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Current Awkward VR Scenes…

5. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Introduction
Observers can also enjoy the attraction.

6. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Goal
Incomprehensible Understandable

8. Object in VR
Observer
VR player
Projector
Cubic
Screen

9. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Key Implementation
Position of Cameras
== Tracked observer’s position
FoV of Cameras
== Width(height) of each wall
Virtual Cameras
Front wall
Rightwall
Leftwall Back wall
Four cameras
(Observer s position)
Front wall
Rightwall
Leftwall
Back wall
Four cameras
(Observer s position)
Front wall
Rightwall
Leftwall
Back wall
Four cameras
(Observer s position)

10. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Key Implementation
Foreground/Background
Front wall
Rightwall
Background
forprojection
Foreground
forprojection
Leftwall
Back wall
Observer
Player
Front wall
Rightwall
Leftwall
Back wall
Four cameras
(Observer s position)

11. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Usage
So you can install ReverseCAVE program to Unity games !! !
ReverseCAVE is made with Unity!

12. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result

13. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
VR Gamer
Observer

14. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result

15. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Preliminary Experiment I
Purpose
To investigate whether the participants can understand the situation
experienced by the VR player.
Conditions
With ReverseCAVE / Without ReverseCAVE
Participants
8 participants (19-23 years old)
Procedure
1) Observe the VR player for 30 seconds under each condition using 2 VR games.
2) Describe what the VR player is doing.

16. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
The number of participants who could understand
correctly what VR gamer was playing.
with
without
100%88%
25% 25%

17. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Preliminary Experiment II
Purpose
To investigate the influence of the observer tracking on the ability
to understand the situation.
Conditions
With tracking / Without tracking
Participants
8 participants (19-23 years old)
Procedure
1) Observe the VR player for 30 seconds under each condition.
2) Answer 5-point Likert scale styled questionnaires related to understanding.

18. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
How well did you understand the relationship
between the VR player and the content?
(1: did not understand at all, 5: completely understood)
There is NO significant difference.
with Tracking
without Tracking
3.50
2.63
M
0.87
0.86
SD
1 2 3 4 5

19. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
How well did you understand the situation?
(1: did not understand at all, 5: completely understood)
There is NO significant difference.
with Tracking
without Tracking
4.13
3.13
M
0.93
1.17
SD
1 2 3 4 5

20. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
How immersive was the experience?
(1: non-immersive, 5: high immersive)
There is a significant difference.
with Tracking
without Tracking
3.50
2.63
M
0.87
0.86
SD
1 2 3 4 5
p < 0.05

21. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Result
• With tracking, the participants felt higher
immersive sense.
• But, the observer tracking did not relate to
the understanding of the VR situation.
Multiple people can see ReverseCAVE simultaneously
and understand what is happening.

22. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Future Work
[1] https://twitter.com/nyutandon/status/892815825136218112/
[2] Hafu Walks The Plank in VR - Vive Prank - YouTube https://www.youtube.com/watch?v=-o7cyzcTLOQ
[3] Jan G., Evgeny S., Julian F., and Enrico B.. ShareVR: Enabling Co-Located Experiences for Virtual Reality between HMD and Non-HMD Users. CHI’17.
[1] [2] [3]
Comparing with other methods
Chroma key Floor projectionLarge display

23. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Interacting w/ VR Player
Interaction
VR Player Observers Players

24. VR Village at SIGGRAPH 2017“Digital Playgroundz: Demonz I.” VR Village at SIGGRAPH 2017

25. Copyright ReverseCAVE team, jiseCHI, INNOLAB, University of Tsukuba.
Contribution
1. Proposed new approach for sharing VR.
2. Presented the proof-of-concept implementation.
3. Investigated the effect of ReverseCAVE and
the influence of the observer tracking
in term of Sharing VR.

26. ReverseCAVE Providing Reverse Perspectives for Sharing VR Experience
Akira Ishii Masaya Tsuruta Ippei Suzuki Shuta Nakamae Tatsuya Minagawa Junichi Suzuki Yoichi Ochiai
U n i v e r s i t y o f Ts u k u b a , Yo i c h i O c h i a i L a b o r a t o r y
Team