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VISUAL INTERPRETATION AND CLASSIFICATION OF LANDSAT DATA APPLIED TO THE STUDY 
OF URBAN STRUCTURES IN WESTERN EUROPE 
M. BOZET, H. DOTU, M. INSTALLE, J. WILMET 
Université Catholique de Louvain Louvain-la-Neuve, Belgium 
The interpretation of Landsat data for urban applications encounters 
many difficulties. First of 211, the satellite sensors which were implemented 
for Earth Resources Research do not match in a very convenient way the necessities 
of land use studies in such areas. Poorly sensitive in the low waves ranges, 
they can not very efficiently discriminate between the numerous reflectances of 
dark surfaces and shaded areas. The small size of many objects which compose 
the so complex realm of urban housing and facilities is also maladjusted to the 
satellite ground resolution. At least, the difficulty to get very accurate 
ground truthes in a so diversified urban universe is very constraining. The pro- 
blem of the anarchical growth of cities however, not only in the third world 
but also in the developed countries, calls for fast and reasonable solutions. 
The outgrowth of towns into the surrounding rural area induces new problems 
related to housing, facilities, traffic on the one hand, to the disorganization 
of rural economy and severe damage to the human environment on the other hand. 
It should be added that this outgrowth brings about many troubles to the spatial 
organization of the cities inner core. For instance the Obsolete character and 
the damage of some ancient districts are on a par with many problems of pollu- 
tion, morbidity and deliquency. The need for permanent spatial control and 
planning of the cities has arisen all around the world. But some specific and 
multitemporal tools of observation are lacking, the rate of the process excee- 
ding that of classical statistical compilation. Aerial photography already is 
a useful tool for detailed surveys. But on a macroscale, the satellite multi- 
temporal recordings may be of complementary use, when the dynamics of the ur- 
banization process is stressed. Its usefulness also lies in its synthetic capa- 
city : The growth of a complete urban system can get overviewed. 
The materials of this paper are scheduled as follows : We first present the 
classification techniques used throughout this study. The use of these methods: 
for urban interpretation is then commented, and finally the results of interpre- 
tation of Brussels and Charleroi images are presented and discussed.