Depth cue combinations for density judgment in three-dimensional display

The present study examined whether different depth cues would interact with the judgment of density differently. Using a 3D projector, we presented random-dot stimuli on fronto-parallel square planes at different depths (-30, -15, 0, +15, or +30 cm from the projection plane) and measured the perceived density of the dots in each depth plane using the method of constant stimuli. The depth of the plane was manipulated with three types of depth cues (binocular disparity, stimulus area, and dot size), which were used separately or all together. The results showed that the averaged PSEs depended on the depth plane when the depth cue was stimulus area, whereas the influences of size and disparity cues on the PSE were relatively weak. However, when the cues were combined, the influence of the area cue on density judgment was largely attenuated. These findings imply that the combination of the depth cues can provide more precise depth perception of the dots and helping interpretations of "3D-valid density".