0000000000809338
AUTHOR
François Sémécurbe
La forme des villes françaises est-elle déterminée par les morphologies bâties et non bâties qui les environnent ? Éléments de réponse apportés par des analyses multifractales
International audience; Des chercheurs en géographie ont montré, depuis les années 90, que les villes contemporaines partagent les caractéristiques morphologiques de certains objets fractals : les bordures urbaines sont très indentées à travers les échelles ; dans chaque ville, le nombre d’agrégats bâti et leur taille suivent une loi de puissance tandis que le nombre d’espaces non bâtis est relié à leur taille selon une autre loi de puissance (Batty & Longley, 1994 ; Frankhauser, 1994). Les dimensions fractales permettent de caractériser au moyen de mesures quantitatives les formes urbaines et ainsi de comparer aussi bien des villes entre elles que des quartiers d’une ville.Nous proposons i…
Local multifractal analysis of marked spatial point processes
In this paper, we develop a methodology for the local estimation of multifractal properties in random 2D fields. The main novelty of our approach lies in introducing a local average of one-dimensional increments, rendering the analysis applicable not only for fully defined images but also for any marked point process where information is not ubiquitously available, e.g. in the context of geospatial data analysis and modeling. We demonstrate the robustness of the estimation by deploying the methodology on a multifractal random field defined as a marked 2D point pattern with three different underlying supports: an equidistant grid (or image), a self-similar and a multifractal Sierpinski carpe…
Analyse de la distribution spatiale des implantations humaines : apports et limites d’indicateurs multi-échelles et trans-échelles
As human beings, it is easy for us to judge visually whether a distribution is dispersed or concentrated. However, the quantitative formalization of our impressions is problematic. It depends on the scales of the chosen analysis. This dependence of indicators on scales has changed. It is initially considered as a barrier to knowledge, it now reflects the multi-scale organisation of the distributions studied. The central objective of this thesis is to investigate the limits and contribution of multi-scale and trans-scale indicators to the study of the spatial distributions of human settlements.Spatial analysis aims at comparing spatial distributions to a uniform distribution. The way in whic…
Exploring the deviations from scale-invariance of spatial distributions of buildings using a Geographically Weighted Fractal Analysis. An application to twenty French middle-size metropolitan areas
In the early twentieth century a handful of French geographers and historians famously suggested that mainland France comprised two agrarian systems: enclosed field systems with scattered settlements in the central and western France, and openfield systems with grouped settlements in eastern France. This division between grouped and scattered settlements can still be found on the outskirts of urban areas. The objective of this paper is to determine whether the shape of urban areas varies with the type of built patterns in their periphery. To this end, we identify and characterise the local and global deviations from scale-invariance of built patterns in metropolitan France. We propose a new…