B 580111 [8 58.010 
  
  
  
  
  
  
  
  
  
1600 $ 1900 0 
D po 0 2000 3000 
son mmu Lanza. a 
Fig..2. 
tudes with such accuracy that sufficient information concerning the 
practicability of the terrain is obtained. For the altitude measurement 
to give this result, it is essential that the contact prints should be made 
on an unshrinkable material, e. g. correctostat cardboard. Corrections of 
measured altitudes due to defects in the orientation of the pictures are 
made with the help of a correction diagram drawn on the basis of 
known altitudes or according to the method of correction with vertical 
parallax measurement worked out at the Royal Institute of Technology 
by Professor B. Hallert. The treatment of the pictures includes an im- 
portant stage of interpretation, implying assessment of the carrying 
capacity of the ground, its degree of moisture etc. 
On the contact prints or on tracing paper are shown the areas which 
are unsuitable for the laying of a highway owing to e. g. poor carrying 
capacity, altitudes, groups of settlements. 
The result is shown in a coherent sketch of the pictures where the 
abovementioned areas are given with their designations. Interesting al- 
titude conditions are also marked in on the sketch. 
The treatment of the sketch yields strips of terrain of varying 
breadth within which the projected route for the road with any possible 
alternatives should run. The route is also marked in on the sketch. See 
fig. 2. 
Thanks to this procedure it is thus possible to eliminate at once those