DELINEATING URBAN AREAS FROM LANDSAT IMAGES USING 
DIGITAL PROCESSING; A COMPARISON WITH GRID- BASED 
PHOTO INTERPRETATION 
Ir. C.A. de Bruijn 
INTERNATIONAL INSTITUTE FOR AERTAL SURVEY AND EARTH 
SCIENCES (ITC), ENSCHEDE, the Netherlands 
Department of URBAN SURVEY 
  
1. Introduction 
During the past decades, urban areas all over the world have known 
considerable physical changes, and planners and decision-makers are 
becoming increasingly aware that they have no suitable monitoring 
systems available to be timely informed on directions and volumes 
of such changes. Not only in developing countries, but also in coun- 
tries with a long administrative tradition, it is often extremely 
difficult to get reliable up-to-date information on the growth and 
extent of the urbanized area. (SMITH et al, 1977). 
In most cases, such à situation may improve drastically by intro- 
ducing aerial photography systematically as a complementary data 
source, (DE BRUIJN et al, 1976), but the low price, the relatively 
easy availability, the digital classification possibilities, and 
the high temporal resolution of satellite imagery makes some 
decision-makers wonder if satellite images could not be used instead. 
With the actual spatial resolution, however, it is obvious that 
satellite information may play only a minor, often accessory role.