A J van Doorn

Utrecht University, Utrecht, Utrecht, Netherlands

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Publications (121)124.76 Total impact

  • Baingio Pinna · Jan Koenderink · Andrea van Doorn
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    ABSTRACT: Here, we address the phenomenology of visual objects, using verbal reports, spontaneous descriptions, answers to questions and responses to suggestions, as well as free associations. We occasionally ask for simple sketches. Such methods allow probing of the deep structure of visual awareness. This is above all revealed by what is not spontaneously mentioned, or is only mentioned by way of incidental properties. It is also disclosed by changes induced by minor variations or additions. We find remarkable agreement over a large number of participants. Thus verbal reports are a powerful probe of visual structure. Similarly to language, "simple visual objects" have deep roots in subsidiary awareness. These "invisible" foundations serve to define simple figures, like a "square", as unique, prototypical objects. The nature of "visual objects" thus involves an extensive "invisible" realm. Without taking this into account, a proper understanding of the nature of the visual object is not possible. Finally, this should lead to a formal syntactical theory of basic visual shapes.
    No preview · Article · Oct 2015 · Philosophia Scientiae
  • Jan Koenderink · Andrea van Doorn · Johan Wagemans
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    ABSTRACT: Three observers performed a task designed to quantify their “pictorial relief” in visual awareness for a photograph of a piece of sculpture. In separate sessions, they were instructed to assume one of two “mental viewpoints.” The main objective was to investigate whether human observers have such command. All three observers could redirect their “mental view direction” by up to 20°. These observers experience “paradoxical monocular” stereopsis, whereas a sizable fraction of the population does not. Moreover, they had some experience in assuming various “viewing modes.” Whereas one cannot generalize to the population at large, these findings at least prove that it is possible to direct the mental viewpoint actively. This is of importance to the visual arts. For instance, academic drawings require one to be simultaneously aware of a “viewing” (for the drawing) and an “illumination direction” (for the shading). Being able to mentally deploy various vantage points is a crucial step from the “visual field” to the “visual space.”
    No preview · Article · Oct 2015 · i-Perception
  • Robert Pepperell · Jan Koenderink · Andrea van Doorn · Baingio Pinna
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    ABSTRACT: Do generic observers in their free-style viewing of postcard-size pictures have a preference for specific modes of perspective rendering? This most likely depends upon the phrasing of the question. Here we consider the feeling of ‘presence’: does the observer experience a sense of being ‘immersed in the scene’? We had 40 Italian naïve participants and 19 British art students rate three types of rendering of ten ‘typical holiday pictures’. All pictures represented 130° over the width of the picture. They were rendered in linear perspective, Hauck maps, and Postel maps. The results are clearcut. About a quarter of the participants prefer linear perspective, whereas the Hauck map is preferred by more than half of the participants. Naïve observers and art students agree. Architectural scenes are somewhat more likely to be preferred in perspective. Preferences are not randomly distributed, but participants have remarkable idiosyncratic affinities, a small group for perspective projection, a larger group for the Hauck map. Such facts might find application in the viewing of photographs on handheld electronic display devices.
    No preview · Article · Oct 2015 · Asia Pacific Journal on Human Rights and the Law
  • Jan Koenderink · Andrea van Doorn · Johan Wagemans
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    ABSTRACT: Local solid shape applies to the surface curvature of small surface patches—essentially regions of approximately constant curvatures—of volumetric objects that are smooth volumetric regions in Euclidean 3-space. This should be distinguished from local shape in pictorial space. The difference is categorical. Although local solid shape has naturally been explored in haptics, results in vision are not forthcoming. We describe a simple experiment in which observers judge shape quality and magnitude of cinematographic presentations. Without prior training, observers readily use continuous shape index and Casorati curvature scales with reasonable resolution.
    No preview · Article · Oct 2015 · i-Perception
  • Jan Koenderink · Andrea van Doorn · Robert Pepperell · Baingio Pinna

    No preview · Article · Oct 2015 · Asia Pacific Journal on Human Rights and the Law
  • Liliana Albertazzi · Jan J Koenderink · Andrea van Doorn
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    ABSTRACT: In our study, for a small number of antonyms, we investigate whether they are cross-modally or ideaesthetically related to the space of colors. We analyze the affinities of seven antonyms (cold-hot, dull-radiant, dead-vivid, soft-hard, transparent-chalky, dry-wet, and acid-treacly) and their intermediate connotations (cool-warm, matt-shiny, numb-lively, mellow-firm, semi-transparent-opaque, semi-dry-moist, and sour-sweet) as a function of color. We find that some antonyms relate to chromatic dimensions, others to achromatic ones. The cold-hot antonym proves to be the most salient dimension. The dry-wet dimension coincides with the cold-hot dimension, with dry corresponding to hot and wet to cold. The acid-treacly dimension proves to be transversal to the cold-hot dimension; hence, the pairs mutually span the chromatic domain. The cold-hot and acid-treacly antonyms perhaps recall Hering's opponent color system. The dull-radiant, transparent-chalky, and dead-vivid pairs depend little upon chromaticity. Of all seven antonyms, only the soft-hard one turns out to be independent of the chromatic structure.
    No preview · Article · Aug 2015 · Perception
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    ABSTRACT: We consider techniques used in the articulation of pictorial relief. The related ‘cue’ best known to vision science is ‘shading’. It is discussed in terms of an inverse optics algorithm known as ‘shape from shading’. However, the familiar techniques of the visual arts count many alternative cues for the articulation of pictorial relief. From an art technical perspective these cues are well known. Although serving a similar purpose as shading proper, they allow a much flatter value scale, making it easier to retain the picture plane, or major tonal areas. Vision research has generally ignored such methods, possibly because they lack an obvious basis in ecological optics. We attempt to rate the power of various techniques on a common ‘shading scale’. We find that naive observers spontaneously use a variety of cues, and that several of these easily equal, or beat, conventional shading. This is of some conceptual interest to vision science, because shading has a generally acknowledged ecological basis, whereas the alternative methods lack this.
    No preview · Article · Mar 2015
  • 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.
    No preview · Article · Feb 2015 · Pattern Recognition Letters
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    ABSTRACT: The Poggendorff illusion is one of the most exhaustively studied illusions. Can it be revived as an interesting problem? Perhaps by moving it to a slightly different domain. Here, we consider the occlusion of a subjectively linear ramp of tonal values. In a simple experiment, we find results closely resembling those of the geometrical Poggendorff. Yet, the "explanations" offered for the latter hardly apply to the former case. Depending upon one's perspective, this may be taken to "revive" the Poggendorff illusion.
    Full-text · Article · Jan 2015 · Perception
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    ABSTRACT: Does human vision deploy a generic template for open landscapes that might fit the gist of current optical input? In an experiment, participants judged depth order in split-field images in which the two fuzzily delineated half-images were filled with different hues. For the majority of observers, we find a systematic dependence of depth order of these half-images on their hue and/or brightness difference. After minor cleaning of the data, we are left with two mutually wellseparated clusters. Correlation with the statistical distribution of hue and brightness in generic "open landscape" photographs reveals that one cluster correlates with hue, the other with brightness. This suggests that human observers indeed at least partly rely on "generic landscape" templates in the psychogenesis of their visual awareness.
    No preview · Article · Jan 2015 · i-Perception
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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.
    Preview · Article · Aug 2014 · Perception
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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.
    Preview · Article · Dec 2013 · Perception
  • 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.
    No preview · Article · Oct 2013 · International Journal of Computer Vision
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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.
    Preview · Article · May 2013 · i-Perception
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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.
    Full-text · Article · May 2013 · i-Perception
  • Jan Koenderink · Andrea van Doorn
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    ABSTRACT: In The Problem of Form (1893), the German sculptor Adolf Hildebrand distinguishes categorically between perception obtained from multiple fixations or vantage points (G.: Bewegungsvorstellungen; we call these ‘assemblages’), and from purely ‘iconic’ imagery (G.: Fernbilder). Only the latter he considers properly ‘artistic’. Hildebrand finds the reason for this ontological distinction in the microgenesis of visual awareness. What to make of this? We analyze the various ‘modes of seeing’ in some detail. The conceptual issues involved are fundamental, and relevant to both vision science and the visual arts.
    No preview · Article · Jan 2013
  • Jan Koenderink · Andrea van Doorn · Johan Wagemans
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    ABSTRACT: Are pictorial spaces evoked by intentionally ambiguous pictures internally coherent? If so, then we expect these to be idiosyncratic. We addressed this issue empirically. Three sheets from the second edition of Piranesi’s Carceri d’Inventione were selected for the experiment. These were compared with a conventional landscape drawing (after a Capriccio by Guardi) as a base line. The pictorial spaces were probed by way of pairwise depth-order judgments. In each image about fifty landmarks were selected, thus yielding over a thousand binary depth-order judgments per image. From such a full set of pairwise comparisons one obtains a linear depth order. This linear order again yields postdictions for the individual pairwise judgments. Actual judgments differ from these postdictions, thereby yielding a convenient handle on the coherence of the pictorial space. Since the Piranesi Carceri are generally considered to be ‘difficult’, ‘ambiguous’ or ‘labyrinthine’, whereas a conventional landscape as the Guardi is designed for its well-defined depth structure, it is expected that they will give rise to very distinct degrees of coherence. This is indeed what we find. We studied the variation of coherence over observers and images in detail. The pictorial locations that are heavily involved in incoherent responses were identified, and the reason for their ambiguous nature traced in the structure of the depth cues provided by the artist (Piranesi). We speculate that the Carceri manage to strike just the right level of ambiguity (between total chaos and obvious structure) so as to render them visually attractive.
    No preview · Article · Jan 2013
  • 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.
    No preview · Article · Oct 2012 · SIAM Journal on Imaging Sciences
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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.
    Preview · Article · Aug 2012 · Cognition
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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.
    Preview · Article · Mar 2012 · i-Perception

Publication Stats

6k Citations
124.76 Total Impact Points

Institutions

  • 1972-2015
    • Utrecht University
      • • Department of Physics and Astronomy
      • • Division of Physics of Man
      • • Division of Zoological Medicine
      • • Laboratory for Physical Geography
      Utrecht, Utrecht, Netherlands
  • 2009-2013
    • Delft University of Technology
      • Department of Industrial Design
      Delft, South Holland, Netherlands
  • 2001
    • Cambridge College
      Cambridge, Massachusetts, United States
  • 1992-1994
    • Netherlands Institute for Space Research, Utrecht
      Utrecht, Utrecht, Netherlands
  • 1974
    • University of Groningen
      • Department of Psychology
      Groningen, Groningen, Netherlands