Phänomene visueller anpassung. I. Bis III. Mitteilung

Süffert, Fritz

doi:10.1007/bf00446393

Cited by 41 publications

(2 citation statements)

References 3 publications

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“…In both examples the direction of the luminance gradient is important. Things tend to appear ‘object-like’ (‘animal’, ‘grain’, etc), that is convex , if they are light on top, dark at bottom, a polarization that can be traced to the predominantly tendency of natural illumination to be directed top down (Metzger 1975; Riedl 1984; Süffert 1932; Thayer 1909). Illumination from above derives from both direct sunlight (the sun generally appearing above the horizon) and overcast skies (the zenith being the brightest patch in the scene) (Minnaert 1993).…”

Section: Introductionmentioning

confidence: 99%

The Shading Cue in Context

2010

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The shading cue is supposed to be a major factor in monocular stereopsis. However, the hypothesis is hardly corroborated by available data. For instance, the conventional stimulus used in perception research, which involves a circular disk with monotonic luminance gradient on a uniform surround, is theoretically ‘explained’ by any quadric surface, including spherical caps or cups (the conventional response categories), cylindrical ruts or ridges, and saddle surfaces. Whereas cylindrical ruts or ridges are reported when the outline is changed from circular to square, saddle surfaces are never reported. We introduce a method that allows us to differentiate between such possible responses. We report observations on a number of variations of the conventional stimulus, including variations of shape and quality of the boundary, and contexts that allow the observer to infer illumination direction. We find strong and expected influences of outline shape, but, perhaps surprisingly, we fail to find any influence of context, and only partial influence of outline quality. Moreover, we report appreciable differences within the generic population. We trace some of the idiosyncrasies (as compared to shape from shading algorithms) of the human observer to generic properties of the environment, in particular the fact that many objects are limited in size and elliptically convex over most of their boundaries.

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Section: Introductionmentioning

confidence: 99%

The Shading Cue in Context

2010

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“…Dennett’s proposals for a better approach to the study of cognitive ethology are hardly unprecedented. Sophisticated and non-Panglossian approaches to the study of adaptation have long been available, and the behavioral sciences include some good examples (Darwin 1872; Süffert 1932). Indeed, the “Panglossian paradigm” is a myth, analogous to the “anecdotal school” of psychology, an expedient motivated by academic salesmen, which continues to be discussed in the literature.…”

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confidence: 99%