developing countries leads to the conclusion that photo-interpretation in this 
field is usually applied on an ad hoc basis and is not used in any integrated 
way, as for example in the recent New York Land Use Inventory (Hardy and 
Shelton 1970, Kreig 1970). 
The following examples of incidentally applied photo-interpretation for 
urban purposes serve as an illustration, since this paper does not aim at com- 
pleteness. It would be a commendable task for an international organisation to 
take the initiative in instituting a comprehensive inventory of the actual use 
of aerial photography for urban purposes, particularly insofar as the developing 
countries are concerned. 
The Situation in the USA 
The ad hoc use of air photographs for urban planning and administration 
is widespread: municipal inspection of building regulations, tax assessment, 
zoning changes, site evaluation, civil engineering, parking and traffic studies, 
and other cases where the information on physico-spatial reality is basic and 
can be extracted directly from the photography (Branch 1971, Avery 1968). 
The main argument for these applications is found in the inexpensive and timely 
way in which photography provides the required data. It may be assumed that 
many applications have proven economically justified, but there is no clear 
and accessible information available as to the extent to which photography is 
used. Especially interesting is the question of why, in a number of cases, aerial 
photographs are nof used. While research has shown the capability of aerial 
photographs to provide the data, actual use may not yet have achieved its 
fullest potential. 
Research has focused strongly during the last few years on multispectral 
scanning from satellites, and emphasis is given to regional and metropolitan 
(large area) surveys, not to urban (small area) surveys. The Census Cities 
Project has demonstrated the capability of satellite imagery in providing land- 
use data to planners. Such data, however, are much too unrefined for munic- 
ipal planners (Lindgren 1973). Research on urban housing and environmental 
quality with remotely sensed data shows encouraging results, but may be 
typical of the US only: the influence of the (regular) plot size distribution, 
plot pattern, and land use pattern is not discussed. Research results may be 
promising for future application, but the representativeness of the pilot