Abstract
Gillam, Blackburn and Nakayama (1999) designed a stereogram containing images equivalent to those created when one views a near surface occluding part of a far surface. This so-called “Da Vinci stereopsis” creates an impression of depth in the absence of conventional binocular disparities. The sign of depth in Da Vinci stereopsis is unambiguous but the magnitude of depth is unspecified. The basis problem is that the viewer has no way of knowing the size of the occluded object.
We have designed displays that remove this ambiguity. The key idea is that a square has the same colour as a transparent background. For one eye, the square just fills a slit in the background so that its lateral edges are not visible. For the other eye, the square is displaced relative to the slit. For this eye, both lateral edges of the square are visible because the background is depicted as transparent. We refer to this depth cue as “monocular transparency”. The greater the displacement of one image of the square relative to the slit, the greater should be the perceived depth. Thus, the magnitude of depth created by monocular transparency is unambiguous if the viewer uses the available information. The effect cannot be due to vergence-induced disparity because the effect occurs when both images are symmetrical and because depth in both directions occurs at the same time.
We measured the depth produced by our display relative to that produced by an adjacent disparity depth probe. For most subjects, the perceived depth of the transparency display matched that of the disparity-defined depth of the probe. Thus, monocular transparency can create good quantitative depth in the absence of binocular disparity.
Gillam, B., Blackwell, S., & Nakayama, K. (1999). Stereopsis based on monocular gaps. Vision Research, 39, 493–502.