The photointerpretation was done in three phases: 
  
  
    
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
  
1. Preliminary interpretation, in which the patterning 
was made and the areas and ground floor coverage of 
the traffic zones was measured, 
2, Field interpretation, in which the patterning was 
checked and together with the field observations the 
number of stories and the floor space distribution 
was estimated, 
Ze Post-field interpretation, in which the measurements 
by pattern, calculations, checking and the overall 
finalization of the data was made. 
It is very difficult to make a difference between what has 
been done with field work and what with photos. The combined 
use of the both techniques in the field will give the best 
results, However, it can be stated that more than 90% of the 
patterning can be made using photointerpretation in 
office only and after the field work all the lacks and dis- 
crepancies in the material can be checked in the post-field 
interpretation in office. 
The benefits received from the use of photos are depending 
on the photo material available, In Tripoli the existence 
of & suitable up-to-date photography was of great importance, 
In ease that the analyzer will have an opportunity to 
influence the specification of the aerial photography to be 
carried out for the survey the information obtained just from 
photos can be more remarkable, In the practical point of 
view in a land use survey of urban environment the existence 
of oblique photos seems to be of bigger importance than the 
colour or colour infrared photos, The combined use of oblique 
and vertical photos should be studied when developing this 
kind of methods further,