ABSTRACT
The natural world has three spatial dimensions, and we need to percieve all three to function within it. Although the images formed on our retinas are twodimensional spatial representations of the world, we employ a variety of cues in order to determine the geometry and depth of the environment around us [343]. Some of these cues, such as binocular disparity or motion parallax, require us to be able to move and perceive the 3D environment directly. Yet our ability to understand depth relationships in scenes is still present even when viewing a photograph, indicating that at least a subset of the necessary information is still present in the 2D representation.
