Vol.5 No.3 2012

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Research paper : Developing an evaluation system of visually induced motion sickness for safe usage of moving images (H. Ujike)−142−Synthesiology - English edition Vol.5 No.3 (2012) evaluation.(4)Return to (2) and repeat.(5)After going through (4) a certain number of times, the trial of VIMS evaluation system is done by the image industry people. The usability of the user interface is improved based on the questionnaire.Depending on the progress of the R&D, the method of constructing the system based on sufficient investigation using various images for the characteristics of the sickness caused by general images can be taken. However, since there are several image factors involved in VIMS and there is a time-series effect, numerous images with combinations of multiple conditions will be necessary to clarify the essential factors. Moreover, considering the effect of individual differences, many subjects must participate in the experiment. Therefore, the number of experiments will be considerable, and the execution will become impractical. From such considerations, to construct the system quickly for this R&D, we employed the method of constructing the system based on the basic characteristic of the VIMS found in the basic experiment and then improving the evaluation accuracy of the system using general images that readily cause sickness.4 Technological elements and issuesThe four technological elements and issues selected to execute the R&D of the VIMS evaluation system are as follows. The relationships of these elemental technologies in the system construction are shown in Fig. 4.(1)Findings pertaining to the biomedical effects of visual global motion(2)Visual global motion analysis of the images(3)VIMS evaluation model(4)Production of images that readily cause sickness based on the image production method(5)Measurement of biomedical effects to increase the accuracy of the VIMS evaluation model4.1 Findings on the biomedical effects of visual global motionWhile there are several factors that affect VIMS, the first factor that should be the subject in constructing the VIMS evaluation system is the visual global motion. Visual global motion is the whole set of motions that occur in the major portion of the visual field, and basically it is the visual motion within the visual field that occur by the relative motion of the body of the observer and the surrounding environment. Therefore, when the visual global motion is displayed in the large field, the observer perceives it as if he/she is in motion. The relative motions of the observer and the surrounding environment include the translational and rotational motions in the yaw axis (up-down vertical direction), the pitch axis (left-right horizontal direction), and the roll axis (to-and-fro horizontal direction) in the Cartesian coordinate system with the observer at the center. Therefore, the corresponding motions can be considered in the visual global motion.The factors of VIMS can be categorized into image content, Fig. 3 R&D procedure for the VIMS evaluation systemTable 1. Factors that affect VIMSGender, age, attitude of viewing, postureSensitivity to motion sicknessCharacteristics of vestibulo-ocular reflex and optokinetic nystagmusTemporal resolution, portability of display (temporal position change)Viewing distance, environmental illuminance, display size, spatial resolution, ranges of luminance/contrast/chromaticity, binocular stereopsisPresentation period, Prior informationSpatial frequency component, luminance, contrast, chromaticityBinocular stereopsis, consistency of perspective, presence of depth hintsOthersSensitivityPerception systemTemporalSpatialTemporal2D space3D spaceDetailsSecondary factorSpatial distribution of velocity, temporal frequency, amplitudeType of motion, velocity, temporal frequency, amplitudeDetailsLocal motionGlobal motionPrimary factorViewer attributeImage presentation conditionImage contentsImprove usability of the user interfaceRepeat several timesCompare the two results and improve the system componentsMeasurement of biomedical effectExperiments concerning viewing of moving imagesResult of the VIMS evaluation modelVisual global motion analysis of the imageMoving image likely to cause sicknessCompose the entire system

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