The contrast should be O.7 * 0.05. The limits of the 
density are 0.4 and 1.2. Fog level should not exceed 
0.2. Normally the contrast of the orthophoto-negative 
is 1.1 because the orthophoto is usually screened for 
printing by diazo or offset methods. The orthophoto 
is exposed on a film with O.1 mm stable polyester 
base. 
If the scale of the orthophoto-negative is not equal 
to the scale of the final photomap - in case the en- 
largement ratio of the orthoprojector is not sufficient - 
the negative is enlarged or reduced in a reproduction 
camera. 
As mentioned already the amount of mosaicing work should 
  
be kept as small as possible by using large longitudinal 
overlap or by pin-point photography. For technical reasons 
this is unfortunately not always possible, e.g. in case of 
large scales which are used for the final design. When 
mosaicing orthophoto-films difficulties will arise in the 
retouching of the cut lines as well as in adjusting the 
differences of density of neighbouring models. If these 
differences are unavoidable and a mosaicing of several 
orthophotos is necessary in case big map sheets are de- 
sired the only way will be to print the orthophotonega- 
tives onto stable, semi-matt paper with a polyester 
layer and then make a conventional mosaic and a new re- 
production. With this relatively expensive procedure one 
can obtain a completely homogeneous image without visible 
loss of quality. 
The final products of the orthophoto maps for highway work 
are photographic prints, diazo copies or offset prints.