A J van Doorn

Utrecht University, Utrecht, Utrecht, Netherlands

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Publications (110)128.93 Total impact

  • Jan Koenderink, Andrea van Doorn, Johan Wagemans
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    ABSTRACT: The visual field is the spatial form of visual awareness, that is, immediate visual experience ignoring qualities and meanings. Such an entity only exists in the discursive representation, for the awareness as such is quality and meaning throughout. Thus the discursive, formal treatment is necessarily limited. We identify a number of important distinctions of a geometrical nature. This description is confronted with experimental phenomenology, that is the psychology of the Gestalt Schools, and with well known principles of artistic practice. We also trace the connections with biology, especially ethology, aesthetics, and the field of cognitive science based upon Cassirer’s concept of symbolic forms.
    Pattern Recognition Letters 02/2015; DOI:10.1016/j.patrec.2015.02.003 · 1.06 Impact Factor
  • Perception 01/2015; DOI:10.1068/i0676sas · 1.11 Impact Factor
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    Jan Koenderink, Andrea van Doorn, Johan Wagemans
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    ABSTRACT: How is pictorial relief represented in visual awareness? Certainly not as a "depth map," but perhaps as a map of local surface attitudes (Koenderink & van Doorn, 1995). Here we consider the possibility that observers might instead, or concurrently, represent local surface shape, a geometrical invariant with respect to motions. Observers judge local surface shape, in a picture of a piece of sculpture, on a five-point categorical scale. Categories are cap-ridge-saddle-rut-cup-flat, where "flat" denotes the absence of shape. We find that observers readily perform such a task, with full resolution of a shape index scale (cap-ridge-saddle-rut-cup), and with excellent self-consistency over days. There exist remarkable inter-observer differences. Over a group of 10 naive observers we find that the dispersion of judgments peaks at the saddle category. There may be a relation of this finding to the history of the topic-Alberti's (1827) omission of the saddle category in his purportedly exhaustive catalog of local surface shapes.
    Perception 01/2014; 5(3):188-204. DOI:10.1068/i0659 · 1.11 Impact Factor
  • J. J. Koenderink, A. J. van Doorn, S. C. Pont
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    ABSTRACT: When a light source moves, the isophotes of the illuminance field (observed as “shading” in the case of Lambertian surfaces) move over the surfaces of illuminated objects. The sense of rotation of the isophotes relative to the sense of rotation of the “surface illuminance flow,” that is the tangential component of the illumination direction over the surface, depends on the Gaussian curvature of the surface. The temporal change of orientation, the “shading twist,” reveals this purely surface related quality. Since the shading twist depends only on the local curvature of the surface it doesn’t matter at all how the light source moves or where the light sources are, the “shading twist” is a pure surface property, that is to say, it behaves as being painted upon the surface. The formal relations pertaining to the shading twist are analyzed and a numerical simulation is presented that fully corroborates the conclusions from the formal study. The algorithm is also tested on a real scene.
    International Journal of Computer Vision 10/2013; 105(1). DOI:10.1007/s11263-013-0626-z · 3.53 Impact Factor
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    Jan Koenderink, Maarten Wijntjes, Andrea van Doorn
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    ABSTRACT: The "zograscope" is a "visual aid" (commonly known as "optical machine" in the 18th century) invented in the mid-18th century, and in general use until the early 20th century. It was intended to view single pictures (thus not stereographic pairs) with both eyes. The optics approximately eliminates the physiological cues (binocular disparity, vergence, accommodation, movement parallax, and image blur) that might indicate the flatness of the picture surface. The spatial structure of pictorial space is due to the remaining pictorial cues. As a consequence, many (or perhaps most) observers are aware of a heightened "plasticity" of the pictorial content for zograscopic as compared with natural viewing. We discuss the optics of the zograscope in some detail. Such an analysis is not available in the literature, whereas common "explanations" of the apparatus are evidently nonsensical. We constructed a zograscope, using modern parts, and present psychophysical data on its performance.
    05/2013; 4(3):192-206. DOI:10.1068/i0585
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    Jan Koenderink, Andrea van Doorn, Johan Wagemans
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    ABSTRACT: SFS (Shape From Shading) theory is based upon the Lambertian paradigm. Our visual demonstrations imply that this paradigm fails to apply to the conventional stimuli used to probe vision.
    01/2013; 4(5):299-302. DOI:10.1068/i0600sas
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    Andrea van Doorn, Jan Koenderink, Johan Wagemans
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    ABSTRACT: "Exocentric pointing in the visual field" involves the setting of a pointer so as to visually point to a target, where both pointer and target are objects in the visual field. Phenomenologically, such pointings show systematic deviations from veridicality of several degrees. The errors are very small in the vertical and horizontal directions, but appreciable in oblique directions. The magnitude of the error is largely independent of the distance between pointer and target for stretches in the range 2-27°. A general conclusion is that the visual field cannot be described in terms of one of the classical homogeneous spaces, or, alternatively, that the results from pointing involve mechanisms that come after geometry proper has been established.
    Perception 01/2013; 4(8):532-42. DOI:10.1068/i0609 · 1.11 Impact Factor
  • Jan Koenderink, Andrea van Doorn, Johan Wagemans
    01/2013; 1(1-2):121-138. DOI:10.1163/22134913-00002003
  • Jan Koenderink, Andrea van Doorn
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    ABSTRACT: “Pictorial space” is the mental structure that appears to be the scaffold for the visual awareness when looking “into” (as opposed to “at”) a picture. Its structure differs from the “visual space” that is the scaffold for the visual awareness when looking into the scene in front of the observer. The structure of pictorial space has been probed empirically and explored theoretically. Here we propose a framework that allows one to handle cases that have been encountered empirically, but thus far have not been explored in a formal, geometrical setting. The framework allows one to handle many idiosyncrasies of human visual observers, as well as to characterize the (frequent) individual differences in a principled manner. This opens the door to a principled formalism of the structure (e.g., quality) of the pictorial spaces evoked by various methods of presentation, as required for applications.
    SIAM Journal on Imaging Sciences 10/2012; 5(4). DOI:10.1137/120861151 · 2.87 Impact Factor
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    Jan Koenderink, Andrea van Doorn, Johan Wagemans
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    ABSTRACT: Cartoon-style line drawings contain very condensed information, after all most of the page stays blank. Yet, they constrain the contents of immediate visual awareness to an extraordinary extent. This is true even for drawings that are - though nominally "representational" - not even in central projection. Moreover, the strokes used in a drawing may stand for a bewildering variety of entities in the world. We studied Picasso drawings from the 1940s in which the artist famously combined multiple viewpoints. We find that the pictorial reliefs obtained from various observers agree to a large extent, and that the differences are of a very specific nature, typically involving variations in the mutual spatial attitudes of rigid body parts in figure studies. Although the purely planar layout of the drawings accounts for much of visual awareness, observers also use the sparse depth cues provided by the artist to evoke volumetric impressions. Observers also freely insert "template knowledge" about the structure of familiar generic objects.
    Cognition 08/2012; 125(3):394-412. DOI:10.1016/j.cognition.2012.07.019 · 3.63 Impact Factor
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    ABSTRACT: We present a novel setup in which real objects made of different materials can be mixed optically. For the materials we chose mutually very different materials, which we assume to represent canonical modes. The appearance of 3D objects consisting of any material can be described as linear superposition of 3D objects of different canonical materials, as in "painterly mixes". In this paper we studied mixtures of matte, glossy and velvety objects, representing diffuse, forward and asperity scattering modes. Observers rated optical mixtures on four scales: matte-glossy, hard-soft, cold-warm, light-heavy. The ratings were done for the three combinations of glossy, matte, and velvety green birds. For each combination we tested 7 weightings. Matte-glossy ratings varied most over the stimuli and showed highest (most glossy) scores for the rather glossy bird and lowest (most matte) for the rather velvety bird. Hard-soft and cold-warm were rated highest (most soft and warm) for rather velvety and lowest (most hard and cold) for rather glossy birds. Light-heavy was rated only somewhat higher (heavier) for rather glossy birds. The ratings varied systematically with the weights of the contributions, corresponding to gradually changing mixtures of material modes. We discuss a range of possibilities for our novel setup.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.916450 · 0.20 Impact Factor
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    Jan Koenderink, Whitman Richards, Andrea J van Doorn
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    ABSTRACT: Local space-time scrambling of optical data leads to violent jerks and dislocations. On masking these, visual awareness of the scene becomes cohesive, with dislocations discounted as amodally occluding foreground. Such cohesive space-time of awareness is technically illusory because ground truth is jumbled whereas awareness is coherent. Apparently the visual field is a construction rather than a (veridical) perception.
    01/2012; 3(3):159-65. DOI:10.1068/i0490sas
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    Jan Koenderink, Whitman Richards, Andrea van Doorn
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    ABSTRACT: We consider operations that change the size of images, either shrinks or blow-ups. Image processing offers numerous possibilities, put at everyone's disposal with such computer programs as Adobe Photoshop. We consider a different class of operations, aimed at immediate visual awareness, rather than pixel arrays. We demonstrate cases of blow-ups that do not sacrifice apparent resolution. This apparent information gain is due to "amodal occlusion."
    01/2012; 3(2):141-5. DOI:10.1068/i0489sas
  • Jan J Koenderink, Andrea van Doorn, Sylvia Pont
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    ABSTRACT: Shape from shading arose from artistic practice, and later experimental psychology, but its formal structure has only been established recently by computer vision. Some of its algorithms have led to useful applications. Psychology has reversely borrowed these formalisms in attempts to come to grips with shading as a depth cue. Results have been less than spectacular. The reason might well be that these formalisms are all based on Euclidean geometry and physics (radiometry), which, are the right tools in third person accounts, but have little relevance to first person accounts, and thus are biologically (and consequently psychologically) of minor interest. We propose a formal theory of the shading cue in the first person account, 'a view from the inside'. Such a perspective is also required for autonomous robots in AI. This formalism cannot be based on Euclidean geometry, nor on radiometry, but on the structure of pictorial space, and the structure of brightness space. The formalism, though different in kind, has a simple relation to the computer vision accounts. It has great robustness, is free from calibration issues, and allows purely local shape inferences. It is especially suited to biological (and thus AI) implementation. We consider a number of predictions and confront them with available empirical evidence.
    Seeing and perceiving 09/2011; 25(3-4):303-38. DOI:10.1163/187847511X590923 · 1.14 Impact Factor
  • Journal of Vision 12/2010; 1(3):39-39. DOI:10.1167/1.3.39 · 2.73 Impact Factor
  • Journal of Vision 11/2010; 2(7):87-87. DOI:10.1167/2.7.87 · 2.73 Impact Factor
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    Andrea J. van Doorn, Huib de Ridder, Jan J. Koenderink
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    ABSTRACT: Pictorial relief depends strongly on “cues” in the image. For isoluminant renderings some cues are missing, namely all information that is related to luminance contrast (e.g., shading, atmospheric perspective). It has been suggested that spatial discrimination and especially pictorial space suffer badly in isoluminant conditions. We have investigated the issue through quantitative measurement of pictorial depth-structure under normal and isoluminant conditions. As stimuli we used monochrome halftone photographs, either as such, or “transposed” to Red/Green or Green/Red hue modulations. We used two distinct methods, one to probe pictorial pose (by way of correspondences settings between pictures of an object in different poses), the other to probe pictorial depth (by way of attitude settings of a gauge figure to a perceptual “fit”). In both experiments the depth reconstructions for Red/Green, Green/Red and monochrome conditions were very similar. Moreover, observers performed equally well in Red/Green, Green/Red and monochrome conditions. Thus, the general conclusion is that observers did not do markedly worse with the isoluminant Red/Green and Green/Red transposed images. Whereas the transposed images certainly looked weird, they were easily interpreted. Much of the structure of pictorial space was apparently preserved. Thus the notion that spatial representations are not sustained under isoluminant conditions should be applied with caution.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2010; DOI:10.1167/5.8.524 · 0.20 Impact Factor
  • Journal of Vision 09/2010; 5(8):558-558. DOI:10.1167/5.8.558 · 2.73 Impact Factor
  • Journal of Vision 06/2010; 7(9):910-910. DOI:10.1167/7.9.910 · 2.73 Impact Factor
  • J. J. Koenderink, S. C. Pont, A. J. van Doorn
    Journal of Vision 06/2010; 6(6):260-260. DOI:10.1167/6.6.260 · 2.73 Impact Factor

Publication Stats

5k Citations
128.93 Total Impact Points


  • 1972–2014
    • Utrecht University
      • • Department of Physics and Astronomy
      • • Division of Physics of Man
      • • Helmholtz Institute
      • • Laboratory for Physical Geography
      • • Division of Zoological Medicine
      Utrecht, Utrecht, Netherlands
  • 2009–2013
    • Technische Universiteit Delft
      • Department of Industrial Design
      Delft, South Holland, Netherlands
  • 1999
    • Bielefeld University
      Bielefeld, North Rhine-Westphalia, Germany
  • 1992–1994
    • Netherlands Institute for Space Research, Utrecht
      Utrecht, Utrecht, Netherlands
  • 1974
    • University of Groningen
      Groningen, Groningen, Netherlands