1 A MULTI-SCALE MORPHOLOGICAL APPROACH FOR DELIMITING URBAN AREAS WORKINGPAPER PRESENTED AT THE CONFERENCE “COMPUTERS IN URBAN PLANNING AND URBAN MANAGEMENT”,

In urban planning, the definition of limits of towns or of town sections is required in particular in the context of zoning. Such definition is purely conventional and does not refer to the morphological reality of urban areas. Even if it is possible to identify limits of zones by means of functional criteria, until now no appropriate method exists to define limits on the base of morphological criteria. This lack becomes particularly obvious when tackling with periurban areas. Thus, it is here proposed to analyse urban limits through a multi-scale approach, which makes it possible to study urban patterns by avoiding the introduction of any presupposition on the urban spatial structure. Different notions are introduced and discussed. The terms of “border”, “limit ” (or “boundary”) and “envelope ” are precisely defined and it is shown that if the urban border can in any case be identified, the external envelope of an urban area does not always exist. These reflections are illustrated by geometrical models on fractal nature. In a first section of this paper, a fractal reference model of urban patterns and borders is introduced. On this basis, the second section of the paper is dedicated to the presentation of a coherent concept the envelope of an urban area, which leads to develop a methodology fo