Parking Flight Urban Area 
The aim was a survey of overnight car parking on public streets in the 
urban area of Enschede (140,000 inhabitants). Two alternatives exist: 
a ground count during the night hours or a photo flight in the very 
early morning. A ground count involves quite some manpower and time, 
and a high degree of organization. A photo flight is easier to organize, 
but is subject to constraints of weather and daylight conditions. 
The time, day and date of the survey flight are critical: it should be 
executed while as many cars as possible are still being parked. The time, 
therefore, should be as early as possible, the flight duration as short 
as possible, and the day carefully selected (i.e. not during vacation 
time). A favorable day is a Sunday (very little early morning traffic), 
early in spring (leaves on the trees still absent). 
For ease and reliability of data take-off, a large scale (e.g. 1:5000) 
is optimal, but simultaneously a short flight duration is required. The 
conflicts between photo-interpretation demands and aerial photography 
constraints make à compromise unavoidable. 
  
  
Condition Data take-off Flight/photography 
Specification constraint or preference 
Weather Bad, overcast Good, sunny, clear 
Time Very early Late (sufficient light) 
Day Sunday Every day (more opportunities) 
Season Early spring Summer (earlier light) 
Flight duration 
Scale and side-lap 
Film 
  
Short 
Large 
Color 
  
Small scale and side-lap, for a 
minimum number of runs 
Black-and-white (faster and cheaper) 
  
The compromise chosen was a scale of 1:12,500 with a Kodak Double-X film 
mro RMK A 15/23), 80% overlap, 23% side-lap, time before 09.00 hours 
summer time, which is GMT+2, while the solar time is GMT+3). Readability 
in shadows of buildings was required. 
The execution of the flight took place in mid-April, around 08.30 hours 
(summer time) with a sun azimuth of + 209 above the horizon and slightly 
diffuse lighting. The flight duration was only 12% minutes (3 runs, 
covering approx. 40 km2, approx. 50 photos), which is a very good performance 
(no reflying of runs was necessary).