Abstract
Depth is the feeling of remoteness, or separateness, that accompanies awareness in human modalities like vision and audition. In specific cases depths can be graded on an ordinal scale, or even measured quantitatively on an interval scale. In the case of pictorial vision this is complicated by the fact that human observers often appear to apply mental transformations that involve depths in distinct visual directions. This implies that a comparison of empirically determined depths between observers involves pictorial space as an integral entity, whereas comparing pictorial depths as such is meaningless. We describe the formal structure of pictorial space purely in the phenomenological domain, without taking recourse to the theories of optics which properly apply to physical space—a distinct ontological domain. We introduce a number of general ways to design and implement methods of geodesy in pictorial space, and discuss some basic problems associated with such measurements. We deal mainly with conceptual issues.
Highlights
“Depth”, as used in the experimental psychology of visual perception (Gibson 1950; Palmer 1999), is conventionally defined as the subjective correlate of “range”, where range is the distance of a fiducial object to the vantage point.(1) For simplicity we consider only the monocular observer
The vantage point is—for all practical purposes—the center of rotation of the eyeball (Graham 1965; von Helmholtz 1856). It is conventionally regarded as the task of vision to coordinate depth with range as well as possible
This is the mainstream ideal of veridical perception (Marr 1982). This turns the bulk of depthrelated vision research into a normative, rather than descriptive, enterprise
Summary
“Depth”, as used in the experimental psychology of visual perception (Gibson 1950; Palmer 1999), is conventionally defined as the subjective correlate of “range”, where range is the distance of a fiducial object to the vantage point.(1) For simplicity we consider only the monocular observer. You measure the length of a body by putting a yardstick next to it, you measure the weight by comparing it with a standard weight using scales, you grade grains by means of sieves, and so forth In all such cases the observer merely has to judge the fit of a pictorial entity with respect to some “gauge object”.(21) For such methods you need to overlay a picture of the gauge object over the fiducial picture. One superimposes a circular blob (say) over each location and lets the observer adjust either relative size or relative color such that the blobs (they tend to look like “spheres”) look “the same” in pictorial space (Figure 16; van Doorn et al 2011) These methods are capable of considerable variation and development
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