- 2091 - 
the trees on the pictures of 75 and 77. Interpretaion 
based on densitometric measurements alone would be complete 
nonsense. 
3.2. Conclusions. 
All previous discussed thoughts induce following conclusions 
DENSITY 1975 
as far as temporal analyses for this subject is concerned : 
5! 00 
1. The colour on CIR photographs of damaged trees should 
be considered always as relative colour differences towardsthe 
healthy trees ; 
of temporal images 
2. Densitometric measurements do not increase the accura- 
cy but contrary induce more interpretation errors ; 
4.00 
3. The interpreter should not only use the colour alone, 
but the whole aspect of the tree, as well as its situation 
in the environment ; 
4. The interpreter should always keep in mind the influen- 
ce of radial displacement, topography, illumination conditions 
00 
and background radiation ; 
5. Stereovision should always be used and the evaluation 
of a tree should be made from several view positions. 
A lateral overlap of 50 % between flight strips proved to 
be usefull in this context. 
.00 
+ 6. The evaluation of the reasons of damage should never 
be made upon single trees or on small groups, but relations 
should be infered from spatial patterns of damaged trees and 
from other associated environmental phenomena. 
7. In order to reduce the influence of different registra- 
tion conditions the scales should not be taken too large and 
  
1.00 
a) 
optical magnification is preferred. 
3.3. Comparison map. 
With the foregoing conclusions in mind interpretations were 
carried out of the situations of 1975 and 1977 of rows 
of trees situated along a dyke. These trees, were also