The Impact of Visibility on Visual Perception and Space Use: The Case of Urban Plazas in Biskra.

Abstract

This thesis aims to explore why some plazas are preferred to others and also why some parts of the same plaza are busier and more preferred by people than others. The investigation springs from the assumption that a good space is a used space and people’s behavior, movement and use is directly related to the visuals fields created by the spatial configuration i.e. visibility. It is also assumed that the use of space is governed by two major factors: Its attractiveness in terms of movement, i.e. how easy for people to move in as its being to-movement and through-movement space; and the conduciveness of its visual properties for people’s activities. This work aims to examine the correlation between the spatial use and isovist properties of plaza spaces with a case study from Algeria. The thesis first starts with a comparative study of four urban plazas within the city center district of Biskra, Algeria, in which the correlation between the number of static people in sitting and standing positions and the syntactic and isovist properties of each plaza is examined. Then focuses is put on each of these plazas to explore why within the same plaza some parts are busier and more preferred by people than others. Believing that a space may have many sub-settings and that its use is determined by the affordances of these sub-settings, the plaza has been subdivided into subspaces based on its physical properties. Each subspace has been investigated further to look for links between visibility and spatial use. Space syntax method and tools are used to investigate into the issue. The Depthmap program, developed by Alasdair Turner, has been used to observe the visibility properties while behavior mapping, i.e. people counting and spatial use mapping, has been used to observe in-situ the spatial use. The results indicated that spatial use is strongly related to visual considerations relevant to the type of activity and that people might undergo some discomfort for visibility matters.