b 
  
  
Appendix to the INT. ARCHIVES OF 
PHOTOGRAMMETRY, Vol. XII:4, 1956 
  
  
Effect of Photo Scale on the Use of Aerial 
Photographs in Swedish Forestry 
Bulletin from the Committee of Forest Photogrammetry 
By Hans Axelson 
Nowadays airphotos are used to a large extent for various 
purposes in Swedish forestry. À fixed photo scale cannot be 
expected favourable for all the different applications of aerial 
photos in forestry. Hitherto, however, it has not been regarded 
justified, for economical reasons, to use different scales for 
different purposes. It is important, therefore, to find out the 
scale which is hest suited for the different applications. 
As aerial photography is more economical the higher the flying 
allitude is, it is of interest to know the highest altitude from 
which pictures can be taken without their usefulness in forestry 
being too limited. 
The scale question has not been much dealt with in literature. 
According to Spurr: Aerial Photographs in Forestry, New York, 
1948, the scale 1: 26 000 is the smallest practical scale for forestry 
purposes and 1:16 000 the ideal scale. In a report from Forest- 
Inventories Section, Department of Affairs and National Re- 
sources, Ottawa, Canada, in 1955, it is pointed out that the scale 
1: 16 000 has been found very little superior to the scale 1: 35 000. 
The Committee of Forest Photogrammetry has found an urgent 
need to carry out research work on photo scales. The Geogra- 
phical Survey Office kindly contributed to the performance of 
the work by taking the photographs required. Erik Welan- 
der was helpful in the planning of the work. Personell of the 
Central Land Survey Office contributed by making measurements 
and S. G. Móller took part in the planning of the investi- 
gations. For technical questions Prof. B. Hallert, Head of 
the Division of Photogrammetry at the Royal Institute of Tech- 
nology, was contacted. The Committee's work has been done by 
the author in co-operation with L. Lindskog and V. Bon- 
desson.