Титульные страницы и содержание

<p>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.</p

sj-vid-2-ipe-10.1177 2041669518774806 -Supplemental material for View From Outside the Viewing Sphere

<p>Supplemental material, sj-vid-2-ipe-10.1177 2041669518774806 for View From Outside the Viewing Sphere by Jan Koenderink, Andrea van Doorn and Robert Pepperell in i-Perception</p

Relief Articulation Techniques

<p>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.</p

Boundaries, Transitions and Passages

Many pictures are approximately piecewise uniform quilts. The patches meet in transitional areas that have a vague, ribbon-like geometry. These borders may occasionally get lost and sometimes pick up again, creating a ‘passage’ that partly blends adjacent patches. This type of structure is widely discussed in treatises on painting technique. Similar effects (lost outlines, passages) occur in drawing. The border regions are characterized by width, or sharpness and amplitude – which is the contrast between the patches on each side. Moreover, border regions have various textural structures. We propose a formal theory of such transitions. Images can be understood as superpositions of border areas. Stylistic changes can be implemented through the selective treatment of borders. The theory is formally similar to, though crucially different in meaning from, the theory of ‘edges’ (a technical term) in image processing. We propose it as a formal framework that enables principled discussion of ‘edge qualities’ (a term used by painters in a way unrelated to the use of ‘edge’ in image processing) in a well-structured manner

Shading and the Landmarks of Relief

<i>Shading </i>is a visual artist’s tool. It enables the indication of ‘landmarks’ inside the outline of shapes. Shading triggers behavioral responses in organisms throughout the animal kingdom and even affects the habitus of plants. Radiometry might be expected to account for the phenomenology. We derive the formal structures of shading that are expected to play a dominant role in perception. That they fail to do so suggests that shading is more of an interface template than a ‘cue’. This fits the artistic use as a ‘releaser’ very well. Pre-modern artists hardly acknowledge causal relations between various photometric variables. Their works show an effective use of various elements in their own right, with­out attempts at causal congruity. Modern art often defies physics on purpose. We identify manifest templates and relate these to conventional techniques in the visual arts