The geometric relational expression of horizontal disparity, viewing distance, and depth magnitude between objects in
stereopsis suggests that, for a given viewing distance, the magnitude of perceived depth of objects would be the same as
long as the disparity magnitudes are the same. However, we found that this is not necessarily the case for random dot
stereograms that depict parallel-overlapping-transparent-stereoscopic-surfaces (POTS). Data from three experiments
indicated that, when the stimulus size is relatively large (e.g., 13 x 20 arc deg), the magnitude of reproduced depth
between two POTS is larger by 6% than that for an identical pair of stereo-surfaces but with an additional stereo-surface
located between the pair. The results are discussed in terms of global stereopsis which "operates" for relatively large
Depth maps are important for generating images with new camera viewpoints from a single source image for
stereoscopic applications. In this study we examined the usefulness of smoothing depth maps for reducing the
cardboard effect that is sometimes observed in stereoscopic images with objects appearing flat like cardboard
pieces. Six stereoscopic image pairs, manifesting different degrees of the cardboard effect, were tested. Depth
maps for each scene were synthesized from the original left-eye images and then smoothed (low-pass filtered).
The smoothed depth maps and the original left-eye images were then used to render new views to create new
"processed" stereoscopic image pairs. Subjects were asked to assess the cardboard effect of the original
stereoscopic images and the processed stereoscopic images on a continuous quality scale, using the doublestimulus
method. In separate sessions, depth quality and visual comfort were also assessed. The results from
16 viewers indicated that the processed stereoscopic image pairs tended to exhibit a reduced cardboard effect,
compared to the original stereoscopic image pairs. Although visual comfort was not compromised with the
smoothing of the depth maps, depth quality was significantly reduced when compared to the original.
The goal of the present study was to examine size perception of objects depicted stereoscopically. Display size, target size, viewing distance, camera convergence distance, disparity information, and the scene background were manipulated. Subjects estimated the perceived height of a set of stereoscopic targets that were projected from photographic slides. The stereoscopic slides were taken with the targets either in a studio with a black background or outdoors with a backdrop of natural vegetation, using three camera convergence distances. The stereo slides were presented on two screens of different sizes and were viewed at three viewing distances. Disparity information was removed in half the trials. For the conditions examined, display and target size had a significant effect on perceived size; disparity and scene background had a small effect; viewing distance and camera convergence distance had a negligible effect. Interestingly, it was found that the range of estimates of perceived height was reduced compared to estimates of the actual targets. Furthermore, for the small display, the smaller targets tended to be perceived the same or a bigger size than the actual targets and the large targets tended to be perceived smaller than the actual targets.