The 6075 overlap gives a base-height ratio of 1:1, which produces what might be regarded as an over- 
exaggerated spatial effect, while the 80% overlap with the base-height ratio 1:2 gives about the same 
effect as the usual 90 wide angle photography with 6094 overlaps. 
In orienting super wide angle pictures in the autograph, one has the advantage that the orientation 
elements are obtained with great accuracy due to the short focal length and the large picture format. 
Orientation is therefore quite easy, even for the beginner, the tilt especially so since the coefficient for 
overcorrection is unity for super wide angle photographs when the orientation points are chosen such 
that picture coordinates are equal to the focal length. 
From the purely geometrical viewpoints, super wide angle photographs offer only advantages. Inci- 
dentally, for certain cartographic purposes, care is recommended in estimation when the limiting 
scale for the identification and interpretation must be stated. Due to the high flight altitude, much will 
depend on selection of the best filter in each case, and on the use of fine-grained film with steep gra- 
dation. The filter question is a matter of experience, while the corresponding films have recently 
been prepared by leading film manufacturers. 
Rules for the filter choice and the limiting scales for special mapping tasks with super wide angle pho- 
tography can unfortunately not be given until more experience has been gathered in photography from 
great heights. As an approximate guide for the compilation of maps at 1:100000, or for plotting at 
1:50000 with the interpretation contents for a 1:100000 map, the negative scale might at first be chosen 
between 1:60000 and 1:80000. The picture scale of 1:60000 might contain in general too much detail. 
On the other hand, a picture scale of 1:120000 has recently been tried experimentally, but there were 
some uncertainties in interpretation which one would not always be prepared to accept. The investi- 
gations made so far show that in most cases the picture scale of 1:80000, together with a well-prepa- 
red interpretation key for the map area, will produce the optimum economies. From this scale it is 
possible to carry out aerial triangulation as well as mapping at 1:50000 pr 1:100000, which is sufficient 
for general planning in the developing countries. 
The next largest picture scale for technical planning and regional development willlie between 1:20000 
and 1:40000. Mostly it will not be recommendable to combine the flying for the general mapping and 
the technical planning. The original small scale 1:100000 maps remain, now as previously, the largest 
single task. Experiences made in the Soviet Union in the preparation of maps at this scale are suffi- 
cient proof that for this job it pays to develop a special line of instruments based on the use of vertical 
photography with the super wide angle lens. The superior picture quality, of which full advantage is 
taken by good observing systems such as in the A9, B9 or B8, and the smooth work progress with 
these instruments due to the rigorous geometrical solution and orthogonal viewing, all lead to an 
optimistic judgement of the present conditions in instruments and methods for original cartographic 
work at small scales. 
19