International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
URBAN DETECTION, DELIMITATION AND MORPHOLOGY: COMPARATIVE
ANALYSIS OF SELECTIVE *MEGACITIES"
B. Alhaddad, B.E. Arellano, J. Roca
CPSV, Centre of Land Policy and Valuations, Polytechnic University of Catalonia (UPC), Av. Diagonal 649, 08028
Barcelona, Spian
Commission VII, WG VII/6
KEY WORDS: Urban Sprawl, Mega-Cities, Artificialized Land, Land Use, Landsat
ABSTRACT:
Over the last 50 years, the world has faced an impressive growth of urban population. The walled city, close to the outside, an
"island" for economic activities and population density within the rural land, has led to the spread of urban life and urban networks
in almost all the territory. There was, as said Margalef (1999), *a topological inversion of the landscape”. The “urban” has gone from
being an island in the ocean of rural land vastness, to represent the totally of the space in which are inserted natural and rural
“systems”. New phenomena such as the fall of the fordist model of production, the spread of urbanization known as urban sprawl,
and the change of scale of the metropolis, covering increasingly large regions, called "megalopolis" (Gottmann, 1961), have
characterized the century. However there are no rigorous databases capable of measuring and evaluating the phenomenon of
megacities and in general the process of urbanization in the contemporary world. The aim of this paper is to detect, identify and
analyze the morphology of the megacities through remote sensing instruments as well as various indicators of landscape. To
understand the structure of these heterogeneous landscapes called megacities, land consumption and spatial complexity needs to be
quantified accurately. Remote sensing might be helpful in evaluating how the different land covers shape urban megaregions. The
morphological landscape analysis allows establishing the analogies and the differences between patterns of cities and studying the
symmetry, growth direction, linearity, complexity and compactness of the urban form. The main objective of this paper is to develop
a new methodology to detect urbanized land of some megacities around the world (Tokyo, Mexico, Chicago, New York, London,
Moscow, Sao Paulo and Shanghai) using Landsat 7 images.
1. INTRODUCTION
1.1 Overview and motivations
The second half of the twentieth century was undoubtedly the
time when there has been a faster urban growth worldwide. The
urban population has grown from 750 million in 1950 to 2860
million in 2000, and now represents over 50% of world
population. The expansion of the cities had its origin in the
model of suburban life began with the generalized use of the
car. A lifestyle based on the “American Dream: one single
family-home, and one (or more) car (s)”, that means mobility
and homeownership. However it has been since the late 70s
when it has had a more dramatic development, as a consequence
of the crisis of metropolitan areas linked to what is called Post-
Fordism economy and some authors have characterized as
counter-urbanization (Berry ) desurbanization (Berg), edge-
cities (Garreau) metapolis (Asher) or diffuse city (Indovina).
Despite the diversity of urban development, the increasing
consumption of land, the excessive use of land as a scarce
resource, it is a constant in the urbanization process in the early
twenty-first century.
In this sense, the urban sprawl, the process of gradual spread
out of urbanization has become a worldwide phenomenon,
especially in the developed world and its environs. The growing
consumption of land, as a result of the extension of highway
networks in urban areas, seems to have become unstoppable and
affects virtually all the contemporary metropolis worldwide.
The literature has discussed deeply the concept of sprawl. Some
of these concepts are: Sprawl is the spreading out of a city and
its suburbs over more and more rural land at the periphery of an
urban area. This involves the conversion of open space (rural
land) into built-up, developed land over time; “Our method of
defining sprawl is to characterize it simply in terms of land
resources consumed to accommodate new urbanization. If land
is being consumed at a faster rate than population growth, then
a metropolitan area can be characterized as "sprawling." If
population is growing more rapidly than land is being
consumed for urbanization, then a metropolitan area can be
characterized as “densifying”.” (Fulton et alt. 2001); or “The
literature on urban sprawl confuses causes, consequences, and
conditions. This article presents a conceptual definition of
sprawl based on eight distinct dimensions of land use patterns:
density, continuity, concentration, clustering, centrality,
nuclearity, mixed uses, and proximity. Sprawl is defined as a
condition of land use that is represented by low values on one
or more of these dimensions.” (Galster et. alt., 2001). However
there is no consensus in defining urban sprawl, because of its
complexity and multidimensional character.
Thereby, the research uses the remote sensing to identify, to
analyse and to measure the urban sprawl in the selected
megacities, using the LandSat7 imagery, with the aim to
compare the different morphologies and to understand the
urbanization process of the metropolitan areas, and then
proceed to get indicators that explain this global phenomenon
objectively and accurately.
1.2 General objectives
The overall objective of the paper is to develop an efficient
technique of remote sensing for monitoring the contemporary
process of urban sprawl. More specifically, it seeks to develop a
