Relative Depth & Figure-Ground Organization

In the image shown on the left which side is closer - Orange or Yellow?
Why is this an important question?

Figure-Ground Organization
This is an important question because the above image is a part of a natural scene shown below. In everyday life identifying and interpreting the visual cues that determine relative depth across image contours (i.e., figure-ground organization) are central problems of vision science. When opaque objects at different environmental distances are optically projected onto a 2D surface so that their projections share an image contour, the laws of optics dictate that the shared image contour belongs to the object that is closer to the point of observation. Because such optical projections lose the spatial dimension of depth, however, the visual system must determine which side of the 2D projection “owns” the shared contour using features of the image regions to determine which side is closer.

Goal
In the 70+ years since the phenomenon was first discovered by Rubin (1921), very little attention has been paid to the importance of shaded and/or textured surfaces. The goal of the following projects is to identify and empirically study of a novel cues to figure-ground organization in images where gradients of shading, highlights, and/or texture provide information about which side of an edge is closer to the viewer.
  • Extremal Edges Study of a cue that biases a region to strongly appear figural or closer to the viewer.
  • Gradient cuts Study of a cue that biases a region against appearing figural. The region appears to be farther from the viewer.
  • by Tandra Ghose , updated February 2009