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c) REMARKS ON THE PENNINGTON PROPOSAL FOR A STAN 
DARD TEST OF STEREOSCOPIC PLOTTING INSTRUMENTS, 
by W. Schermerhorn. 
7 ) SUEDE 
STEREO - MAPS 
by A. Frey Samsioe, Dr. Techn. and Percy H. Tham, Dr. Techn. Stockolm. 
Since the 6 ih International Congress of Photogrammetry was held in the 
Hague in 1948, various types of maps, permitting a three-dimensional pre 
sentation of terrain, have been discussed. Instead of the traditional contour 
lines, with their limitations, direct reproduction of the ground has been the 
ultimate aim. 
The moulded relief maps of plastic material, particularly used in the 
U.S.A. are an interesting development. By the exaggeration of the height 
scale the model gives an impression similar to that obtained by a pair of 
pictures stereoscopically observed. 
With regard to stereo-maps, a new type is proposed by W.A. Bruckla- 
cher, described in Bildmessung und Luftbildwesen, 1-1950, Berlin. This 
« map », however, is not a real map, but is a systematic assembling of pairs 
of pictures in such a manner that a « window-frame effect » is obtained. 
This « grid » aids the visual relief impression. The use of this method, as is 
mentionned by the proposer, depends on a very good flight performance and 
also on the fulfilment of other necessary conditions. Brucklacher goes on to 
say that the production of a true-to-nature anaglyph map would be impos 
sible in view of the central projection of the image. 
In actual fact the production of such a map is possible, and the 
authors have made an anaglyph Map that is completely true to nature. It is 
composed of about 7 pictures fitted together in conformity with the « com 
pilation » method used in Sweden. A check of the accuracy of the map has 
fully established that it is impossible to find the boundaries of the pictures 
when observing the map with a mirror stereoscope. In presenting this map 
it needs only be said that the right (red) « master map » is a normal map 
true to scale; the left (blue) « parallax map » gives the necessary parallaxes. 
There are no other points to be taken into consideration other than that of 
increasing the overlap to the double, i. e. from 60 % to 80 %. With these 
pictures on file, it will always be possible to obtain a three-dimensions map