a moving platform has certain advantages (recording vehicle trajecto- 
ries or traffic behavior). 
There should be no limitation of the aerial survey technique to large- 
format mapping cameras and special aerial survey airplanes. 
Ape For a number of applications, small-format (35 or 70 mm) vertical or 
y: oblique photography is also an appropriate technology, and a feasible 
alternative for large-format (23 cm) aerial survey. (See Poerbo & 
Shubert, 1978, Leppänen, 1918). If & small single-engined high-winged 
ents plane ( from which a door may be removed or a window can be opened) is 
available, it is possible to secure a complete coverage with obliques 
(with an angle of obliquity of 309 or less ), flying straight runs. A 
35 mm camera (with motor-drive for a fast image sequence) will provide 
an inexpensive alternative for small areas, as a very satisfactory 
photographic quality can be realized. The problem of screening 
e- : : tims y : 
d (buildings hiding cars) can be overcome by selecting appropriately 
ed closely-spaced runs. With minor modifications, also vertical photo- 
graphy can be realized (see Clegg & Scherz, 1975, Woodcock, 1976, 
Zsilinsky, 1969, 1972). 
tem Small-format systems seem to be more appropriate for single-purpose 
e applications (e.g. recreation surveys), while large-format aerial 
To a survey systems are more geared to multi-purpose applications. However, 
: the trade-off between a simple small-format system (with a plane 
| tó without a camera port in the floor) and a more sophisticated large- 
. format mapping system should be established by further research and 
3 applications. 
should : ; 
; Clear advantages of small-format camera systems and light aircraft are 
y the general availability of cameras, processing facilities and air- 
planes, low cost, and short-notice implementation. It is, therefore, 
"a particularly suited for low-budget organizations in developing coun- 
à tries, operating within an unsophisticated technological infrastructure. 
Jther Moreover, traffic and land-use control totals can be established, as 
well as data sources be cross-checked to validate them in a relative 
inexpensive way (see Harrison & Anderson-Nicholls, 1918). 
Two experimental examples of parking surveys, realized in close coope- 
>r— ; : eg : 
ration with municipal user agencies, are discussed below. 
gra-