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Optical Marionette: Graphical Manipulation of Human's Walking Direction - UIST 2016

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We present a novel manipulation method that subconsciously changes the walking direction of users via visual processing on a head mounted display (HMD). Unlike existing navigation systems that require users to recognize information and then follow directions as two separate, conscious processes, the proposed method guides users without them needing to pay attention to the information provided by the navigation system and also allows them to be graphically manipulated by controllers. In the proposed system, users perceive the real world by means of stereo images provided by a stereo camera and the HMD. Specifically, while walking, the navigation system provides users with real-time feedback by processing the images they have just perceived and giving them visual stimuli. This study examined two image-processing methods for manipulation of human's walking direction: moving stripe pattern and changing focal region. Experimental results indicate that the changing focal region method most effectively leads walkers as it changes their walking path by approximately 200 mm/m on average.

Paper (PDF): http://akira.io/papers/om_paper_uist16.pdf
Video: https://www.youtube.com/watch?v=RTGpr6p582o
Project page: http://digitalnature.slis.tsukuba.ac.jp/2016/06/moh/

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Optical Marionette: Graphical Manipulation of Human's Walking Direction - UIST 2016

  1. 1. Optical Marionette: Graphical Manipulation of Human’s Walking Direction Akira Ishii, Ippei Suzuki, Shinji Sakamoto, Keita Kanai Kazuki Takazawa, Hiraku Doi, Yoichi Ochiai (Digital Nature Group, University of Tsukuba, Japan)
  2. 2. Background | Redirected Walking n Manipulation technique of human’s walking direction for VR environment n Uses only visual feedback for the manipulation n Enables users to explore a virtual world that is quite larger than the real environment 2 Figure by Matsumoto et al. 2016
  3. 3. Introduction | Motivation n Suspected there are possibilities that human’s walking direction could be manipulated using only visual feedback in the real environment like a Redirected Walking in VR 3 To manipulate user’s walking direction using only visual feedback in the real environment Our goal
  4. 4. Introduction | To This End n Examined various image-processing methods to manipulate walking path n Investigated how to manipulate the walking path using the image-processing methods 4 We found effective reorienting method using an HMD in the real environment
  5. 5. Implementation n The camera is attached to the HMD n Users perceive the real world by video provided by an HMD and stereo camera n So we can coordinate users’ sight in this setup 5 HMD Stereo camera = See-through
  6. 6. Implementation | Hardware n HMD: Oculus Rift DK 2 n Stereo camera: Ovrvision 6 HMD Camera
  7. 7. Implementation | Hardware 7 User’s sight via HMD + camera while walking
  8. 8. Implementation | Flow 8
  9. 9. Implementation | Flow 9 Investigated effective image processing in a pilot study
  10. 10. Pilot Study n Purpose - To determine which of the image processing methods have the most effect on a human’s walking path n Participants - 5 participants (1 female); 18-22 ages n 6 image processing methods n Task - Walk straight 10 m for each image processing methods 10
  11. 11. Pilot Study | Result 11
  12. 12. Implementation | Changing Focal Region (CFR) 12 Raw video from camera Video that users see via HMD Crops the raw image Shifts the cropped area
  13. 13. Implementation | Changing Focal Region (CFR) 13 Raw video from camera Video that users see via HMD Crops the raw image Shifts the cropped area User is asked to go to the B, however, actually he is going to the A
  14. 14. Experiment 14 n Purpose -To determine how to control the walking direction using Changing focal region method n Participants -16 participants -Had not prior knowledge of our experiment n Task -Walk straight 24 m for each image processing
  15. 15. Experiment | Experimental Design n Image processing methods - No processing (raw video) - Magnification - Magnification was added to the image-processing methods for comparison because it is used in Changing focal region method. This enabled us to identify the effects of image magnification and to reveal the pure effects of changing the focal region (shifting images). - Changing focal region (slow / fast) - Scroll speed of the cropped area in the slow condition was 0.5 px/frame - In the fast condition, the scroll speed of the cropped area was twice the scroll speed in the slow condition 15 Magnification + Shifting Changing focal region
  16. 16. Experiment | Experimental Design n Locations -Hallway - Narrow - Several hints for spatial perception (such as walls) -Outside - Large space - No hint for spatial perception 16
  17. 17. 1. Completed pre-SSQ (Simulator Sickness Questionnaire) 2. Walked straight for 24 m each of image processing at 2 locations -At 4 m, guided to the left -At 14 m, guided to the right 3. Completed post-SSQ Experiment | Procedure 17
  18. 18. Result | Simulator Sickness Questionnaire n Analyzed the SSQ scores with t-test -No significant difference between pre-SSQ and post-SSQ -Pre-SSQ: 4.7 (SD = 4.7) -Post-SSQ: 6.7 (SD = 8.3) 18 I did not feel any motion sickness J
  19. 19. Result | No processing 19 Position of participants [m] Distance from starting point [m]
  20. 20. Result | Changing focal region (fast) 20 Position of participants [m] Distance from starting point [m]
  21. 21. Result 21 No processing Changing focal region No processing Changing focal region
  22. 22. Result | Hallway n Significant effect -No processing ― Changing focal region (slow/fast) -Magnification ― Changing focal region (slow/fast) n No significant effect -No processing ― Magnification 22 Position of participants [m] No processing Magnification CFR (slow) CFR (fast)
  23. 23. Result | Hallway n Amount of the manipulation for Changing focal region -Slow: 65.3 mm/m - If you walk 2 m, your position moves by 10 cm horizontally -Fast: 75.3 mm/m 23 No Amount of manipulation [mm] * guide to left ** guide to right
  24. 24. Result | Outside n Significant effect -No processing ― Changing focal region (slow/fast) -Magnification ― Changing focal region (slow/fast) n No significant effect -No processing ― Magnification 24 Position of participants [m] No processing Magnification CFR (slow) CFR (fast)
  25. 25. Result | Outside n Amount of the manipulation for Changing focal region -Slow: 105.2 mm/m -Fast: 199.2 mm/m 25 No Amount of manipulation [mm] * guide to left ** guide to right
  26. 26. Result | Pure Effect of CFR n No significant effect between No processing and Magnification -This indicates that the cropped image by itself did not affect the participants’ walking paths -It is clear that the participants’ walking paths were affected by movement of the cropped area of Changing focal region 26
  27. 27. Result | Hallway vs. Outside n Significant effect within the locations -The outside participants were affected more by the manipulation method - In the hallway, the participants could not move more than 1.1 m because the with of the hallway is 2.2 m - Thus, the mean value of the position change in the hallway was smaller than that in the outside 27
  28. 28. Result | Slow vs. Fast n Changing focal region (fast) was significantly more effective than the slow condition -Slow: 105.2 mm/m -Fast: 199.2 mm/m (at outside) 28
  29. 29. Discussion | Spatial Perception n Past research reported Changing the FOV has effects on spatial perception [1, 2] n No horizontal spatial perception effect on our result -because no significant difference between No processing and Magnification n By contrast, we could not determine whether there was any depth perception effect 29 In this study [1] Campos, J., Freitas, P., Turner, E., Wong, M., and Sun, H. The effect of optical magnification/minimization on distance estimation by stationary and walking observers. Journal of Vision 7, 9 (June 2007), 1028. [2] Kuhl, S. A., Thompson, W. B., and Creem-Regehr, S. H. HMD calibration and its effects on distance judgments. ACM Transactions on Applied Perception 6, 3 (September 2009), 19:1–19:20.
  30. 30. Discussion | Cognitive Resource n Conventional navigations require users to recognize information (go to the right) and then follow directions n Our method directly affects users’ bodies so that it can control them without requiring user recognition process 30 Does our method have lighter burden than conventional navigations?
  31. 31. Discussion | Cognitive Resource n Significant amount of cognitive resources is required for redirected walking in VR [3] Similarly, our method might require some cognitive resources 31 We plan to investigate how much cognitive resources are really required by users to follow the manipulation [3] Bruder, G., Lubas, P., and Steinicke, F. Cognitive resource demands of redirected walking. IEEE Transactions on Visualization and Computer Graphics 21, 4 (April 2015), 539–544.
  32. 32. Discussion | Feasibility n Demonstrated our method at SIGGRAPH 2016 E-Tech n Over 700 people were successfully manipulated 32 Direction: Go straight to B
  33. 33. Applications | AR Contents n In see-through AR contents, to control of human’s walking path is important because users might conflict each other 33
  34. 34. Applications | Walker Navigation n There is possibility of walker navigation system, if we can increase the amount of manipulation of users’ walking direction 34
  35. 35. Related Work | Galvanic vestibular stimulation (GVS) [4] n Administers electrical stimulation to the back of ears (the vestibules) n Controls the walker’s sense of balance 35 [4] Maeda, T., Ando, H., Iizuka, H., Yonemura, T., Kondo, D., and Niwa, M. Parasitic humanoid: The wearable robotics as a behavioral assist interface like oneness between horse and rider. In Proc. AH ’11, 18:1–18:8.
  36. 36. Related Work | Electrical Muscle Stimulation (EMS) [5] n EMS-based walker navigation system n Controls walker’s legs using EMS 36 [5] Max Pfeiffer, Tim Du ̈nte, Stefan Schneegass, Florian Alt, Michael Rohs. Cruise Control for Pedestrians: Controlling Walking Direction using Electrical Muscle Stimulation. CHI 2015, pp.2505-2514, 2015.
  37. 37. Related Work n These methods use electrical stimulation n Our method is vision-based manipulation technique of human’s walking direction using only visual feedback 37 [4] Max Pfeiffer, Tim Du ̈nte, Stefan Schneegass, Florian Alt, Michael Rohs. Cruise Control for Pedestrians: Controlling Walking Direction using Electrical Muscle Stimulation. CHI 2015, pp.2505-2514, 2015.
  38. 38. Optical Marionette: n We found effective image-processing methods for walker movement control with an HMD n We investigated of the effects of the image-processing methods via a user study n Changing focal region method was most effective, and changed walking path by about 200 mm/m 38 Akira Ishii, Ippei Suzuki, Shinji Sakamoto, Keita Kanai Kazuki Takazawa, Hiraku Doi, Yoichi Ochiai (University of Tsukuba) ishii@akira.io Graphical Manipulation of Human’s Walking Direction

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