Visual illusion of the change of the size of architectural and urban objects observed upon a change of the observer's distance: Parameters that influence it phenomenologically

Abstract

This paper explores the visual phenomena of a seeming change of the target-object's size (as a focus of concrete visual perception) in the function of an observer's motion so that it 'seems' contrary to the law of linear perspective (in the sense of an expected increase of the target volume/monumentality - by getting closer or a decrease - by getting farther away). This phenomenon is described in a geometrical and perceptual aspect; the result of this comprehensive approach led to identify parameters that determine it phenomenologically. It was established that the explored visual phenomenon is a specific 'size illusion', i.e. an 'angular size illusion' that occurs when influenced by factors of the perceptual kind - activated by a specific dynamic relationship (on a visual plan) between the target object and its surrounding competitive objects, as an observer moves. By understanding the character of this phenomenon (both in a geometrical and perceptual sense), it is possible to apply the acquired knowledge in practice - in programming the visual effects to be obtained (such as to visually optimize or minimize the monumentality of targeted objects) in all architectural and urban fields (planning, designing and reconstruction).