Sweden 18 
Material and Equipment. Contact prints or enlarged copies, some 
times rectified, of aerial photographs on approximate scales of 1:20 000 
—1:30 000 are mainly used. The photo material is seldom extensively 
worked up photogrammetrically. Single or stereo-pictures are usually 
photo-interpretated in pocket stereoscopes, mirror stereoscopes or some 
times Oude Delft stereoscopes. Simple scales, more rarely stereometers, 
are used for measurements. 
Accurate photogrammetric mapping is done by the Swedish photo- 
grammetric service organizations. 
Organization. Large scale forestry concerns sometimes have specially 
trained members of their staffs in the photogrammetric work. The 
Board of Crown Lands and Forests for instance has a specially trained 
forester in charge of it, and so has the Swedish Cellulose Company. 
In other cases some photogrammetrically trained employee couples the 
photogrammetric work with his other activities. 
Photogrammetric Research in Forestry. Photogrammetric research 
work in forestry has just been centralized in a Committee of Forest 
Photogrammetry. The Committee has six members representing diffe 
rent branches of forestry and such of the civil services as have more 
extensive use for photogrammetry. The Committee carries out research 
and is in constant collaboration with forestry and related technical 
research and educational bodies and also with the civil and military ser 
vices and authorities, to whom photogrammetric work is of importance. 
E. Some Investigations in Terrestrial Photogrammetry 
The Photogrammetric Division at the Institute of Technology has 
made use of terrestrial photogrammetry for many investigations in va 
rious branches of science, e. g. technical (measurement of deforma 
tions, determination of flow-wave shapes and currents in liquids, etc.), 
meteorological (determination of the shapes of and changes in clouds), 
ballistic, archeological, and other branches. The said Division has also 
constructed a special camera for stereo-photography, the internal orien 
tation and base of which can both be varied to suit different photo 
graphing conditions. 
Many investigations have been made in intimate collaboration with 
other scientific institutions, for instance the medical investigations men 
tioned below. 
During the period 1952—1955 Adams-Ray has continued his stereo- 
photogrammetric researches for determining the dimensional varia 
tions of finger swellings. 
Adams-Ray, Flagberg, Fljelmstrom and Olsson ((18] and [30]) 
have discovered a method of Roentgen stereo-photogrammetry by which 
they have in the course of a medical investigation determined the varia 
tions in the volume of a dog’s liver. By means of silver pellets surgically