Motion Vectors of Images and Cybersickness Tohru Kiryu Graduate School of Science and Technology, Center for Transdisciplinary Research Niigata University
T. Kiryu, Niigata University Physiological Background Motion sickness Simulator sickness vestibular stimulation postural control otolith-sympathetic reflex vestibular system proprioceptive inputs real and virtual visual input vestibular autonomic regulation Cybersickness cardiovascular responses active and passive MSNA: muscle sympathetic nerve activity Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Approaches �� Database of Biosignals under Vection-Induced Images �� Featuring the Components of Image by Motion Vectors �� Analysis by Synthesized Images (random dot pattern) �� Estimation of System Function by Multivariate ARX Model Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Rating of Image Strength of Sickness under Vection-Induced Images � = ( prediction - required level for images ) targets for evaluation ( experience for image contents ) � �������� ( brightness, frame size, and frame rate etc. ) � Hierarchy of Image Components visual characteristics prediction brightness brightness Motion Vector color scenario (scene) resolution filtering frame rate Specification of Display Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Overview watching biosignal biosignal extraction extraction motion vector motion vector real image real image synthesis synthesis biosignal biosignal watching random dot image by CG random dot image by CG Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Quantization of Image by Motion Vector Local Motion Vector Global Motion Vector Local Motion Vector Global Motion Vector Local Motion Vector Global Motion Vector pan zoom distant view camera tilt motion of camera local motion in a screen local motion in a screen Post frame y Current frame y tilt Bottom up approach x x Block matching method Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Experiments under Real Images real images real images subjects subjects ten healthy young subjects (eight males and two Parachute ten healthy young subjects (eight males and two female from 21 to 24 yrs. old) female from 21 to 24 yrs. old) Bobsleigh boat boat Go cart Hang glider Measured Biosignals Measured Biosignals Mountain-bike Mountain-bike ECG : chest ECG : chest Car race Car race Respiration : tube sensors around the chest Bungee jump Respiration : tube sensors around the chest and the abdomen diving diving and the abdomen Blood Pressure : tonometry method Blood Pressure : tonometry method Bike race Bike race Blood flow : Laser Doppler at thumb sphere of Blood flow : Laser Doppler at thumb sphere of Vehicle left hand left hand experiencing video Perspiration : Capsule type sensor at thumb Perspiration : Capsule type sensor at thumb sphere of left hand sphere of left hand at Niigata University � December, 2002 � Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Correlation between Pan and Right/Left (1,1) (1,2) (1,3) (1,4) (1,5) (2,1) (2,2) (2,3) (2,4) (2,5) (3,1) (3,2) (3,3) (3,4) (3,5) (4,1) (4,2) (4,3) (4,4) (4,5) (5,1) (5,2) (5,3) (5,4) (5,5) bobsleigh time [sec] Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Correlation between Pan and Right/Left (1,1) (1,2) (1,3) (1,4) (1,5) (2,1) (2,2) (2,3) (2,4) (2,5) (3,1) (3,2) (3,3) (3,4) (3,5) (4,1) (4,2) (4,3) (4,4) (4,5) (5,1) (5,2) (5,3) (5,4) (5,5) mountain-bike mountain-bike time [sec] Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Info. on Autonomic Nervous Activity 2 LF power HF time-frequency R-R interval 1 representation 120 0 20 40 60 80 100 time[sec] - LF component (0.04-0.15[Hz]): Mayer Wave related band - HF component (0.15-0.45[Hz]): Respiratory Sinus Arrhythmia related band 1. Estimating the averages of LF and HF components under a target image for each subject. 2. Determination of the intervals for sickness. ( RR LF 120% < RR LF ) � ( RR HF 80% > RR HF ) Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Specification of Trigger Points 2 RR LF RR LF 120% < RR LF ( RR LF 120% < RR LF ) � ( RR HF 80% > RR HF ) 1 triggered times triggered times A A 2 B B 1 D D power E E 2 subjects subject F F 1 G G H H 2 J J 0 20 40 60 80 100 120 0 20 40 60 80 100 120 1 time [sec] time [sec] 0 20 40 60 80 100 120 time [sec] Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Time-Frequency Representation of GMVs bobsleigh zoom 15 zoom frequency [Hz] 0 15 15 pan frequency [Hz] 0 10 15 tilt 5 0 time [sec] 20 40 60 0 0 mountain-bike 20 22 24 26 15 time[sec] zoom frequency [Hz] 0 specific frequency band: 15 specific frequency band: pan 0.1-3.0 [Hz] 0.1-3.0 [Hz] 0 15 tilt 0 time [sec] 0 20 40 60 80 100 Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Cases for Random Dot Patterns task 1 task 2 task 3 task 4 task 5 task 6 task 7 S S PT S ZPT S ZT S ZPT S ZP S ZPT S S: still, Z: zoom, P: pan, T: tilt task 3 subject G F C D C I B G time [sec] 11.7 47.8 66.9 92.7 104.0 106.7 114.3 115.3 task 5 subject C B I J H E C 14.7 54.2 57.8 90.2 103.3 110.4 118.8 time [sec] task 7 subject J B G D F C G 7.1 17.5 66.4 78.4 85.1 86.9 106.2 time [sec] - Sickness was evoked for 22 epochs for 9 subjects. - 14 of 22 epochs showed the same time-frequency representation of motion vector for real images Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Validation of Sickness Evoked Intervals task 1 task 2 task 3 task 4 task 5 task 6 task 7 S S PT S ZPT S ZT S ZPT S ZP S ZPT S S: still, Z: zoom, P: pan, T: tilt Power of the frequency band (0.1 – 3.0 Hz) of a zoom component 1 power 0.5 0 20 40 60 80 100 120 time [sec] Sequences of sickness evoked intervals task 3 task 5 task 7 Real Image Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
Discussion T. Kiryu, Niigata University – prediction of traveling direction by motion vectors – zoom component affected on autonomic regulation, referring to the experimental results. zoom component might be used for zoom component might be used for motion [a.u.] prediction of traveling direction prediction of traveling direction zoom zoom 1.1 1.0 0.9 Quick vibration appeared in motion frequency [Hz] vector could disturb prediction 10 8 6 4 2 time [sec] 50 55 60 65 70 Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Process of Cybersickness vestibular autonomic regulation 2 LF power HF delay 1 exposure time 120 0 20 40 60 80 100 time[sec] visual input zoom 0.16 vestibular system 0 - frequency band -0.16 - power 20 30 40 50 60 70 - delay frequency band & power - exposure time Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
T. Kiryu, Niigata University Conclusion - We studied influences of vection-induced images in the relationships between autonomic nervous activity related indices and motion vectors of images. - Autonomic nervous activity was evaluated from R-R interval, blood pressure, and respiration. The motion vectors including global and local motion vectors were estimated by the data compression technique. - According to the time-varying behavior of motion vectors, the specific frequency band (0.1 – 3.0 Hz) of a zoom component possibly caused cybersickness. - However, we have not yet concluded whether the unpleasant feeling was caused by the content of the vection-induced image or the structure of the image scene (the frame rate, the vibration of objects, etc). - Moreover conditions of subjects should be evaluated at each experiment. Evaluating Risks of Vection-Induced images by Motion Vectors : Symposium at 43th JSMBE, Kanazawa, May 20, 2004
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