5 
flying time for their particular photography. This will be on such limited areas that the 
photographs can in general only be used for their special purposes for which they were 
taken. There may be a few exceptions which I will mention later on. We will consider in 
particular the combination of the production of a small scale general map with the 
requirements for general economic planning as described in 2b, c and d. It is obvious that 
this requires two different photographie coverages of which the scale 1 :20,000 for 
forestry and soil survey has already been indicated. 
b. Photography. 
The main problem in this case is which kind of photography and in particular which 
scale of photography should be used for the production of such a general topographic 
map. The Russians used for this purpose the 70 mm super wide-angle camera for scales 
of photography between 1: 35,000 and 1: 70,000 with naturally the larger scales in the 
cultivated and more densely populated areas. Outside Russia we find that the photo- 
graphic scale 1 : 50,000, taken with 6” wide-angle camera, is nearly everywhere the 
smallest scale of photography used for the production of small-scale topographie maps. 
Only in case of the use of transverse low oblique photography, as in some cases in the 
U.S.A., the average distance between the flight lines can be larger than that possible 
with a normal wide-angle camera from the same flying height, giving at the edges of 
the photograph a much smaller scale. 
The problem is whether the situation will change in principle with the introduction 
of super wide-angle cameras like the Wild RC9, which has a principle distance of 88 mm 
and 23 X 23 em image size and which corresponds to the 70 mm Russar camera. Will it 
be possible to replace the wide-angle photography 1 : 50,000 for these purposes by super 
Aviogon photography in a scale of 1 : 70,000 to 1 : 80,000 using in both cases about the 
same flying height? This height has the advantage of remaining within the possibilities 
of normal civil aircraft. If saying yes to this question, I assume that the research work, 
which will be carried out for the photography, will show the improvement, which makes 
this answer fully acceptable. 
After this decision we come to the photogrammetric restitution of this new type of 
photographs. Which of the latest developments will influence the restitution procedure 
already now and which will do so — perhaps even more — in the near future? In order to 
answer this question we will go through the procedure step by step and consider the 
possibilities of improvement in each of them. 
c. The use of camera orientation instruments. 
Assuming an air photography in the scale 1: 75,000 taken with a super wide angle 
camera, the first question is which additional camera orientation instruments should be 
used during exposure and which further precautions should be taken. 
It will be desirable, in particular in mountainous terrain, to take photographs with 
a lateral overlap of abt. 2596 and a longitudinal overlap of 80%. If aerial triangulation 
must be carried out, this can be done in pairs with 60% overlap and if there are some- 
where dead areas, pairs with 80% can be used for plotting. 
Furthermore a statoscope and an airborne profile recorder must be used. Although 
it may be that in the near future stabilized mounts can be used, which give a high 
precision (standard deviation of y and « of about 1 centigrade), for the time being we 
must do without these new tools and prove that we do not need them for this kind of 
maps. 
Considering the necessity of precision for the determination of the lateral tilt, we 
see that due to the width of the strip in this case, the mean square value of the lateral 
tilt of one centigrade corresponds to a mean square error in height in the centre of the 
lateral overlap of abt. 1 m.