Ambient optic array

Abstract: A theory of mobility using nonvisual stimuli and cognitive control process is proposed to augment Gibson's (1958, 1979) explanations of visual guidance. Nonvisual processes are clearly important to the totally blind, who often manage considerable independent mobility in the absence of vision, but are also important to the sighted. Mobility can be directed by visual control stimuli in the ambient optic array, by nonvisual control stimuli, as well as by processes of spatial learning, including stimulus-response (S-R) rote learning, motor plans, schemas, and cognitive maps. The selection of processes and strategies depends on the availability of particular information or on task demands. Attentional processes select stimuli for locomotor control within any particular modality and select between perceptual and cognitive processes. The skill of traveling through the spatial environment, avoiding obstacles, and traveling directly or indirectly toward goals, is a general characteristic of animal behavior and is described here by the term mobility. Although this term has a special connotation within blindness rehabilitation (Welsh & Blasch. 1980), it is used here to describe the overall processes of guidance by which both blind and sighted travelers move through space. The study of mobility encompasses several more traditional research concerns, such as space perception, motor control, and spatial cognition. Until recently there has been little research related to general psychological theory of mobility. A comparison may be made with the study of reading, where considerable research has taken place on component tasks such as letter extraction, word recognition, and eye movements, but where there has been comparatively little interest until recently in the general rules of the process (see Haber, 1978).

Abstract: The study of biological motion perception was introduced into vision research some 40 years ago by Swedish psychologist Gunnar Johansson. Since that time, the questions and approaches have changed considerably. While early work on biological motion perception was primarily concerned with mechanism of perceptual organization, the more recent research emphasizes on the social significance of human and animal motion. In tracing the evolution of the term “biological motion” and its use, this chapter attempts to characterize and classify the different questions and experimental paradigms that have dominated research on biological motion perception over the last few decades. Gunnar Johansson's biological motion: structure from non-rigid motion The term “biological motion” is closely associated with the work of Gunnar Johansson (1911 – 1998), an experimental psychologist who received his PhD from the University of Stockholm and then taught and conducted research at the University of Uppsala, Sweden, for most of his career. Hardly any study on biological motion is published without a reference to at least one of the two papers which Johansson published on his observation that observers can effortlessly make out a human figure behind a degraded visual stimulus that consists of nothing but a few dots moving along with the major joints of a human body (Johansson, 1973; 1976). Gunnar Johansson was an extremely prolific researcher, was well connected, and had strong ties to many of the personalities that had shaped European post-war experimental psychology. In addition to the two papers on the perception of human motion, he published almost 100 papers over the course of his career. He was strongly influenced by the school of Gestalt Psychology. Wolfgang Kohler had visited him several times in Uppsala and the two had planned collaborative work shortly before Kohler's unexpected death in 1967. Johansson also maintained a long academic relationship with James J. Gibson. With Gibson he shared an interest in the question how the visual system samples and then extracts information about discrete objects and events from the ambient optic array (i.e., the everchanging, continuous stream of light irradiating the location of the observer from all directions). Particularly, the two friends discussed (and sometimes argued about) the way the visual system distinguishes between the visual motion induced by the observer himself while moving through the environment, and the motion of objects, animals, and people relative to the visual environment. Johansson's approach to this question was his “vector analysis” theory which he had first laid out in his doctoral thesis (Johansson, 1950). The theory was rooted in Gestalt theory, specifically in Duncker's work on induced motion (Duncker, 1928), and it was based on Johansson's own experimental work for his doctoral thesis under the supervision of Gestalt psychologist David Katz at Stockholm University. Johansson's experiments had set out to demonstrate how the human visual system would break down the motion of simple objects into “common” motion encoded in a global reference system, and “relative” motion represented within an object-based reference system. Common motion of the entire visual field with respect to the observer would be indicative of the observer’s motion, while motion relative to the global, allocentric reference system has the potential to characterize objects – both in terms of motion parallax induced by the observer and in terms of the object's own motion. On the object level itself, the same distinction seemed to make sense, too. The motion common to all the parts of an object describes its trajectory through space, while the relative motion between the parts bears information about changes of orientation or the configuration of the internal structure of a deformable

Abstract: Workshop 2. Session 2.3: Mapping home Abstract. Residences’ mental perception, especially spatial perceptions of their built-environment is crucial in shaping their overall quality of life and environmental perception. The increasing intangibility of mental geography may be caused by lack of empirical and quantitative approach. We will introduce an empirical and quantitative approach of analysing mental geography, based on James Gibson’s direct perception theory. Gibson argued that spatial perceptions of the visible environment were constructed by ambient optic arrays, or photonic arrays reflected by environmental geometries and received by perceiver’s eyes. We’ve developed a GIS (geographic information system)-based 3D visibility analysis, Viewsphere, capable of computing the spatial properties of ambient optic arrays, based on the volumetric amount of space occupied by the photonic arrays. Using this analysis, the perceptual quality of residential or urban open space can be measured. We argue that the spatial properties expressed by quantitative perceptual indices may represent the residences’ spatial perception of their residential environment. Comprehensive understanding of a residential setting’s mental geography may be achieved by mapping of spatial perceptions through interpolating perceptual indices from a grid of sample points. Two test cases were conducted on an environmental setting of typical Singapore’s public housing estate. Singapore’s public housing programme is well-known for its success of housing most of the nation’s population in its high-density, high-rise environment. Using this analytical methodology, the impact of high-density, high-rise residential environment on residence’s mental geography can be empirically understood.

Abstract: Publisher Summary This chapter discusses the concept of ecological optics. The established branches of optics are appropriate for the study of visual sensations but not for the study of visual perception. Visual perception is not based on having sensations but on attention to the information in light. The essence of ecological optics is the demonstration that there is information in ambient light. However, the common assumption of physical, geometric, and physiological optics is that there is no information in light, that is, no information about the ordinary things from which the light is reflected. Students of traditional optics, like students of sensory physiology, tend to be impatient with what they consider philosophical issues. They like to believe that science progresses by the accumulation of facts and not by polemics. The heart of ecological optics is the concept of the ambient optic array at a point of observation. The ambient array needs to be distinguished from the ambient light. The former constitutes stimulus information; the latter constitutes stimulus energy. The purpose of ecological optics is not to explain the visibility of stars, lighthouses, or spectral colors. It is not to improve the design of optical instruments or the prescribing of spectacles. It is not concerned with dazzle or afterimages. Its purpose is to explain how animals see their environment, chiefly illuminated surfaces. Ecological optics is less concerned with seeing light than with the seeing of things by means of light.