Abstract
Stereoscopic 3D television can suffer from a “puppet theater effect”, where figures are perceived as unnaturally small. This does not normally affect 2D television, perhaps because viewers interpret the image as being produced by a correctly-sized object viewed from a suitably far distance, whereas the additional binocular cues to distance rule out this interpretation in S3D displays. In this study, we examined the interaction between binocular disparity and perceived size. Viewers were shown a picture of a standard credit card - a familiar everyday object with a definite size – presented on a S3D TV screen with varying physical size and binocular disparity. They reported whether it appeared smaller or larger than a real card. The viewing distance was 50, 100 or 200cm. The credit card was presented in the middle of the screen either on a black background (absolute disparity condition), or on a textured background (relative disparity condition). If a “familiar size” cue dominated, viewers would always perceive the image as being credit-card-sized, so the percentage of “bigger” judgments would not depend on image size or disparity. Alternatively, viewers might base their answers on the size of the physical image on the screen, if they were able to detect this. Thirdly, viewers might combine the binocular information about the distance of the virtual card with the angular subtense of the image, and base their answers on the implied size of the virtual card. Our results indicate that viewers use a mixture of the last two strategies. At all 3 viewing distances, they do take disparity into account, especially when this is more precise (relative disparity condition). However, they are also influenced by the physical size of the image on the screen. We present a mathematical model of how viewers combine size and disparity in this task.
Meeting abstract presented at VSS 2015