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to replace the incorrect term land use by space use. The information for the 
“actual space use” maps (city centre 1 : 2500, whole urban area 1 : 12,500) 
was collected by aerial photographic interpretation (ITC flight, June 1975, 
scale 1 : 5000, black-and-white, 80% forward overlap, 20% side overlap), com- 
plemented and checked by field surveys. During the field survey, experimental 
use was made of mobile radio communication. The field party was directed by 
the photo-interpreter, who could thereby process the field information receiv- 
ed in the real-time mode. First impressions are that this method is more ef- 
ficient (compared to photo-interpretation with a subsequent field check), and 
also that simultaneous completeness and accuracy of information is enhanced. 
A more complete description of the space use map of Enschede will appear in 
due course in the ITC Journal. In general, urban survey techniques can be 
developed even further, and an improvement in pragmatic procedures and a 
closer connection with urban planners’ demands should be aimed at. 
Reliability and efficiency are key problems in land use surveys in urban 
areas. Reliability, apart from customary interpretation factors such as inter- 
preters’ skill and the scale and quality of the photographs, is influenced 
strongly (in land use surveys) by the correspondence of site adaptation and 
activity (actual use), site adaptation being the prime indicator on an image 
of only indirectly visible activities. The site adaptation is the building type or 
other special site facility, or, in general, the adaptation of a site to the 
activities on the site. Examples are: church building, office building, pavement. 
The site adaptation, by being of a certain type, limits activity within or 
on it, but does not determine activity. If a building (or other form of site 
adaptation) did determine activity, there would be no practical need to dis- 
tinguish between the two. Knowing one, we would also know the other. But 
activities are to some extent adaptable, and perhaps each one can use any 
building type, while being most at home in a specific type (Guttenberg 1959). 
Examples of activities which would not be at home are a supermarket in a 
church, a school in an office building, an office in a row house, or a prison 
camp in a football stadium. It is essentially the site adaptation which is 
detected and recognised on the aerial photograph. Site adaptation can be 
interpreted with very high reliability from aerial photographs. A number of 
activities are very closely connected with a specific type of site adaptation 
(oil refinery, railway terminal building, filling station): the activities then 
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