tracing on photos has been deliberately kept down, as tracing on photos 
always tends in some degree to interfere with comprehensive study of the 
photos. This operation progressed at the rate of 1 photoprint of 30X30 em 
(covering an area of which on the average one third belonged to the 
company) per 8 hours. The. work was carried out by means of stereo-vision 
of contact prints on the scale 1: 20 000, as well as with the aid of existing 
drawn maps dating from the years 1929— 1944. Though the demand for 
accuracy was great, it was possible in this way to keep the field work to 
a minimum. The details on the completed photo map were then drawn in 
Indian ink on the negative of the photo map. Subsequently copies were 
made from this negative on the scale of 1: 10 000, and these together with 
standard prints on the scale 1:20 000 are used as current forest maps. 
The copies carried for daily use are pasted on cloth, size 25X25 em. For 
some regions there are photo maps with contour lines added. 
To keep track of the photos, the company has the following system with 
the designations shown: 
1. for company forest blocks, present on each photo; localization by the 
use of a grid on general topographic maps. 
2. for the photo registration numbers, arranged in order of coordinates. 
3. for the photos which cover separate forest blocks. 
As no taking of photographs nor the construction of frames was re- 
quired the costs have been kept comparatively low. In 1948 the cost per 
hectare was a total of 0.30 crown, where the company land was in large 
blocks. Because of dispersion the cost would in fact amount to about 
2—3 limes as much. The area mapped was about 1 200 sq. km. 
Kopparfors AB 
This company's forests are situated in southern Norrland (see fig. 3), 
where managed forestry has been practised for a considerable time. Stands 
are of good size and clearly delineated, which facilitates mapping from the 
ground and by aerial photos. The forest maps are about 30 years old and 
are now being replaced by fresh ones —- both drawn maps and photo ma- 
terial — when photogrammetrical material can be conveniently obtained. 
Up to now use has chiefly been made of sheets of the economic map, on 
the scale 1:10 000, size 50X50 em, prepared by the Geographical Survey 
Office for Gävleborg county. 
The economic map constitutes an invaluable basic map for forest mapp- 
ing, as it gives the true position of the basic features, mainly property 
boundaries, roads ete. Stand boundaries, trails and other forest details 
are located by stereovision on contact prints on the scale 1: 20 000. At the 
same time the cutting class of the stand is specified. Distinction is made 
between 6 classes, as follows: 1) regenerations, 2) young growth, 3) 
medium age growth, 4) mature stands, 5) residual stands and 6) stands 
of unsatisfactory density. Field check and completion in the field has been 
considered unnecessary, even though portions of the trails and haul roads, 
especially, have not been identified on the aerial photos. Contour lines 
have been available from the maps of the Geographical Survey Office. 
These have been transferred to the photo map, scale 1: 10 000, which serves 
as a basic map for the economic map, whereas drawn forest maps on the 
same scale are not furnished with contour lines. On the drawn maps the 
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