phenomena and problems. This is largely due to a fast spreading urbanisation 
proeess all over the world, caused by rapid population growth, a push and pull 
migration to the city, and fundamental changes of a social and economic 
nature. s 
This continuing process of change and development has reached such 
dimensions that scientific analysis and professional know-how are badly 
needed for dealing with the manifold and complex problems of urban admin- 
istration, management and planning. For this scientific and professional 
approach, efficient and effective methods of collecting and analysing reliable 
information on physical, social and economic features are indispensable. The 
gathering of spatial data in such a dynamic field requires much time-consuming 
work, while the necessary manpower and funds are often limited. By using 
aerial photography, the necessary information can be obtained from photo- 
interpretation in combination with statistical and other techniques and 
presented in the form of thematic maps, diagrams, graphs and reports. 
With these considerations in mind, the International Institute for Aerial 
Survey and Earth Sciences (ITC) established, in 1968, a new department for 
research and training in urban survey with aerial photography. This paper 
presents a comprehensive review of current developments in this field so as to 
stimulate international discussion in regard to future possibilities. 
2 Operational Use of Aerial Photography for Urban Survey: 
standard and ad hoc applications 
The most extensive and commercially well established use of aerial 
photography in urban areas is for the purpose of topographic and cadastral 
mapping. In this field, the photographic image is used mainly as a source of 
geometric information; auxiliary topographic photo-interpretation is limited 
to the identification of those objects which by tradition are considered to be 
basic data for the making and updating of topographic maps. This type of 
photographic data collection is a standard procedure, in common use through- 
out the world. Thematic photo-interpretation for urban planning and admin- 
istration is also frequently used, but apparently it seems to function rarely as 
part of a standard information procedure. Although the extent of the use of 
aerial photography for urban purposes has not been systematically inventoried, 
the available information from both sides of the Atlantic and from the