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Assessing the Zone of Comfort in Stereoscopic Displays using EEG  [PDF]
Jérémy Frey,Léonard Pommereau,Fabien Lotte,Martin Hachet
Computer Science , 2014, DOI: 10.1145/2559206.2581191
Abstract: The conflict between vergence (eye movement) and accommodation (crystalline lens deformation) occurs in every stereoscopic display. It could cause important stress outside the "zone of comfort", when stereoscopic effect is too strong. This conflict has already been studied using questionnaires, during viewing sessions of several minutes. The present pilot study describes an experimental protocol which compares two different comfort conditions using electroencephalography (EEG) over short viewing sequences. Analyses showed significant differences both in event-related potentials (ERP) and in frequency bands power. An uncomfortable stereoscopy correlates with a weaker negative component and a delayed positive component in ERP. It also induces a power decrease in the alpha band and increases in theta and beta bands. With fast responses to stimuli, EEG is likely to enable the conception of adaptive systems, which could tune the stereoscopic experience according to each viewer.
Estimating Visual Comfort in Stereoscopic Displays Using Electroencephalography: A Proof-of-Concept  [PDF]
Jérémy Frey,Aurélien Appriou,Fabien Lotte,Martin Hachet
Computer Science , 2015,
Abstract: With stereoscopic displays, a depth sensation that is too strong could impede visual comfort and result in fatigue or pain. Electroencephalography (EEG) is a technology which records brain activity. We used it to develop a novel brain-computer interface that monitors users' states in order to reduce visual strain. We present the first proof-of-concept system that discriminates comfortable conditions from uncomfortable ones during stereoscopic vision using EEG. It reacts within 1s to depth variations, achieving 63% accuracy on average and 74% when 7 consecutive variations are measured. This study could lead to adaptive systems that automatically suit stereoscopic displays to users and viewing conditions.
Experimental Verification of Correlation between Objective and Subjective Evaluation of Passenger Car Vibration Comfort  [cached]
Michael Valasek,Jan Pelikan,Jaroslav Ulehla,Ondrej Vaculin
Bulletin of Applied Mechanics , 2009,
Abstract: The paper deals with the experimental investigation of the correlation between objective and subjective evaluation of vibration comfort in passenger cars. The ride comfort plays an important role in the vehicle design as well as in vehicle judgment. Current standard approaches towards vibration comfort evaluation more or less focus on one-dimensional vibration evaluation of human body response. This paper describes the results of experimental verification of a new approach for vibration comfort in passenger cars. This new approach measures the influence of multiple vibration modes of a vehicle on the integral subjective human vibration perception. The experiments have verified that the correlation between the objective and subjective vibration comfort evaluation is almost 1:1. Moreover this paper describes the repeated experiments that prove the concept in larger scale.
Electrical Vestibular Stimuli to Enhance Vestibulo-Motor Output and Improve Subject Comfort  [PDF]
Patrick A. Forbes, Christopher J. Dakin, Anoek M. Geers, Martijn P. Vlaar, Riender Happee, Gunter P. Siegmund, Alfred C. Schouten, Jean-Sébastien Blouin
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084385
Abstract: Electrical vestibular stimulation is often used to assess vestibulo-motor and postural responses in both clinical and research settings. Stochastic vestibular stimulation (SVS) is a recently established technique with many advantages over its square-wave counterpart; however, the evoked muscle responses remain relatively small. Although the vestibular-evoked responses can be enhanced by increasing the stimulus amplitude, subjects often perceive these higher intensity electrical stimuli as noxious or painful. Here, we developed multisine vestibular stimulation (MVS) signals that include precise frequency contributions to increase signal-to-noise ratios (SNR) of stimulus-evoked muscle and motor responses. Subjects were exposed to three different MVS stimuli to establish that: 1) MVS signals evoke equivalent vestibulo-motor responses compared to SVS while improving subject comfort and reducing experimentation time, 2) stimulus-evoked vestibulo-motor responses are reliably estimated as a linear system and 3) specific components of the cumulant density time domain vestibulo-motor responses can be targeted by controlling the frequency content of the input stimulus. Our results revealed that in comparison to SVS, MVS signals increased the SNR 3–6 times, reduced the minimum experimentation time by 85% and improved subjective measures of comfort by 20–80%. Vestibulo-motor responses measured using both EMG and force were not substantially affected by nonlinear distortions. In addition, by limiting the contribution of high frequencies within the MVS input stimulus, the magnitude of the medium latency time domain motor output response was increased by 58%. These results demonstrate that MVS stimuli can be designed to target and enhance vestibulo-motor output responses while simultaneously improving subject comfort, which should prove beneficial for both research and clinical applications.
Spatial Tactile Brain-Computer Interface Paradigm Applying Vibration Stimuli to Large Areas of User's Back  [PDF]
Takumi Kodama,Shoji Makino,Tomasz M. Rutkowski
Computer Science , 2014, DOI: 10.3217/978-3-85125-378-8-32
Abstract: We aim at an augmentation of communication abilities of amyotrophic lateral sclerosis (ALS) patients by creating a brain-computer interface (BCI) which can control a computer or other device by using only brain activity. As a method, we use a stimulus-driven BCI based on vibration stimuli delivered via a gaming pad to the user's back. We identify P300 responses from brain activity data in response to the vibration stimuli. The user's intentions are classified according to the P300 responses recorded in the EEG. From the results of the psychophysical and online BCI experiments, we are able to classify the P300 responses very accurately, which proves the effectiveness of the proposed method.
Stereoscopic Cinema  [PDF]
Frédéric Devernay,Paul Beardsley
Computer Science , 2015, DOI: 10.1007/978-3-642-12392-4
Abstract: Stereoscopic cinema has seen a surge of activity in recent years, and for the first time all of the major Hollywood studios released 3-D movies in 2009. This is happening alongside the adoption of 3-D technology for sports broadcasting, and the arrival of 3-D TVs for the home. Two previous attempts to introduce 3-D cinema in the 1950s and the 1980s failed because the contemporary technology was immature and resulted in viewer discomfort. But current technologies -- such as accurately-adjustable 3-D camera rigs with onboard computers to automatically inform a camera operator of inappropriate stereoscopic shots, digital processing for post-shooting rectification of the 3-D imagery, digital projectors for accurate positioning of the two stereo projections on the cinema screen, and polarized silver screens to reduce cross-talk between the viewers left- and right-eyes -- mean that the viewer experience is at a much higher level of quality than in the past. Even so, creation of stereoscopic cinema is an open, active research area, and there are many challenges from acquisition to post-production to automatic adaptation for different-sized display. This chapter describes the current state-of-the-art in stereoscopic cinema, and directions of future work.
Quality Assessment of Stereoscopic Images  [cached]
Alexandre Benoit,Patrick Le Callet,Patrizio Campisi,Romain Cousseau
EURASIP Journal on Image and Video Processing , 2009, DOI: 10.1155/2008/659024
Abstract: Several metrics have been proposed in literature to assess the perceptual quality of two-dimensional images. However, no similar effort has been devoted to quality assessment of stereoscopic images. Therefore, in this paper, we review the different issues related to 3D visualization, and we propose a quality metric for the assessment of stereopairs using the fusion of 2D quality metrics and of the depth information. The proposed metric is evaluated using the SAMVIQ methodology for subjective assessment. Specifically, distortions deriving from coding are taken into account and the quality degradation of the stereopair is estimated by means of subjective tests.
Quality Assessment of Stereoscopic Images  [cached]
Benoit Alexandre,Le Callet Patrick,Campisi Patrizio,Cousseau Romain
EURASIP Journal on Image and Video Processing , 2008,
Abstract: Several metrics have been proposed in literature to assess the perceptual quality of two-dimensional images. However, no similar effort has been devoted to quality assessment of stereoscopic images. Therefore, in this paper, we review the different issues related to 3D visualization, and we propose a quality metric for the assessment of stereopairs using the fusion of 2D quality metrics and of the depth information. The proposed metric is evaluated using the SAMVIQ methodology for subjective assessment. Specifically, distortions deriving from coding are taken into account and the quality degradation of the stereopair is estimated by means of subjective tests.
Observations with the HEGRA stereoscopic system  [PDF]
D. Horns,for the HEGRA collaboration
Physics , 2001,
Abstract: The HEGRA system of imaging air Cherenkov telescopes has successfully pioneered the stereoscopic observation technique of extensive air showers. The observational method is briefly described and important results of recent observations of sources of photons with TeV($=10^{12}$ eV)-energies are summarized: The first detection of a TeV $\gamma$-ray signal from the shell-type supernova remnant Cassiopeia A and preliminary results obtained from the observation of strong variability of the extragalactic source Mkn 421 during observations carried out from February to May 2000.
Redundancy of stereoscopic images: Experimental Evaluation  [PDF]
L. P. Yaroslavsky,J. Campos,M. Espinola,I. Ideses
Physics , 2005, DOI: 10.1364/OPEX.13.010895
Abstract: With the recent advancement in visualization devices over the last years, we are seeing a growing market for stereoscopic content. In order to convey 3D content by means of stereoscopic displays, one needs to transmit and display at least 2 points of view of the video content. This has profound implications on the resources required to transmit the content, as well as demands on the complexity of the visualization system. It is known that stereoscopic images are redundant, which may prove useful for compression and may have positive effect on the construction of the visualization device. In this paper we describe an experimental evaluation of data redundancy in color stereoscopic images. In the experiments with computer generated and real life and test stereo images, several observers visually tested the stereopsis threshold and accuracy of parallax measuring in anaglyphs and stereograms as functions of the blur degree of one of two stereo images and color saturation threshold in one of two stereo images for which full color 3D perception with no visible color degradations is maintained. The experiments support a theoretical estimate that one has to add, to data required to reproduce one of two stereoscopic images, only several percents of that amount of data in order to achieve stereoscopic perception.
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