12 
Photogrammetry in Application to Small-Scale Cartography 
The recent development of WILD Instruments 
Part 2 
by H. KASPER, Heerbrugg (Switzerland). 
A comparative investigation !) showed that amongst the various possibilities for a 
wide use of aero-photogrammetry in small-scale cartography 1 : 50.000 and 1 : 100.000, 
the method based om photographs taken vertically with a distortionfree super-wide-angle 
lens merits preference to all others. 
The urgency of opening out large territories (for which maps are not available) 
demands survey methods for the compilation of maps on the scale 1 : 100.000 that meet 
the following requirements: 
1. The maps for the economic planning must be made ava/lable in the shortest time 
possible. 
2. 'The production costs of these maps must be low. 
3. Nevertheless, they must be of such accuracy not only to meet the momentary require- 
ments for the first development stages but furthermore the stricter demands of the 
later general technical planning and allowing their complementing with the aid of 
relatively simple means. 
The investigation of the conditions for the photographic coverage showed that eco- 
nomy, accuracy and simple survey-technique can be combined on condition that the area 
photographed per picture is considerably larger than that covered vertically by a 90* 
wide-angle camera lens, for example the Aviogon f : 5.6. 
As it is impracticable to increase the flight altitude in the necessary measure, the 
only effective means available is the use of a camera lens with a much wider angular 
field. 
The desired maximum is to be found at about 120? (1332). 
These finCings are decisive for the geometrical conditions under which the photo- 
graphs are taken. 
For vertical photographs a 60% overlap corresponds to a base ratio of B : H - 1, 
and an 80% overlap to the also favorable ratio B : H = 0,5. 
The largest picture scale is obtained with the negative size 23 X 23 em (9 X 97). 
The corresponding focal length is approx. 9 cm (31/47). 
  
  
TABLE 1 
Flight Altitude Aviogon f — 15 em (6") Super-Aviogon f — 9 em (31/5") 
m | ft Pict. Scale | Area per Pict. Scale Area per 
H picture H picture 
1: 1:— 
/ | km? | sq. miles J km? sq. miles 
3000 10,000 1 20,000 21 8 1 : 223,323 58 22 
6000 20,000 Fl 40,000 83 52 1: 66,667 230 90 
9000 30,000 1 60,000 | 190 72 1 : 100,000 520 200 
12000 | 40,000 1 : 80,000 330 130 1.: 133,333 930 360 
15000 50,000 |1 : 100,000, 520 200 1: 166,067 1450 560 
  
  
  
1) Photogrammetria XII 1955/56 nr, 1.