In this situation, it is essential to develop time-saving methods of 
comprehensive building surveying. Remote sensing is one tool, often a 
very useful one. In many cases additional sources of information must 
be used. and aerial photographs are often very convenient in such 
combined studies. 
I will relate a few studies where aerial photographs were used to 
describe certain features of a built environment. 
The Swedish Civil Defence Administration commissioned our Department 
to study population, use of land and buildings; types of residences: 
and building density in four Swedish communities. The result was to be 
presented on maps which were to be used as examples in civil defence 
planning. It ought to be noted that this was not from the beginning a 
research project but more or less an ordinary planners' commission 
where we had to study unconventional methods as a part of the work. 
Some of the required information was fairly easy to get hold of. The 
population; for instance; could be mapped with satisfactory accuracy 
with the census-registration and employment statistics as a basis. 
Land use could be studied on master plans and town plans. Building 
density and types of residential houses; however, were difficult to 
determine. In Uppsala, the first community to be studied, we tried to 
derive data by interviewing communal officials and by studying floor 
space indexes. The quality of information thus accessible varied very 
much and the result was not satisfying. A fairly extensive amount of 
field surveying was needed. In spite of this, we were not able to map 
the building density, but had to present rather scanty floor index 
tables. 
At this point, I have to comment a little upon the role chance plays in 
our choice of work methods. In Sweden, most architects never work with 
remote sensing and photogrammetry. These subjects are not included in 
our training. We knew, of course, that aerial photographs existed and 
were used for cartographic purposes: but we had no idea of the use we 
could make of them. But I have a daughter, at that time about ten years 
old, and she had a very good school-friend. I met the father of this girl 
at a parents’ meeting at the school. and we started to talk about our