Sweden 14
Scales 1:1 000, 1:2 000, 1 m interval, some 3 000 ha.
„ 1:4 000, 1:5 000, 2 „ „ „ 13 000 „
„ 1:8 000,1:10 000,5,, „ „ 52 500,,
For its planning of large power transmission lines the State Power
Board has also made use of photogrammetry. This work is as yet part
ly experimental. The Board is thus attempting to stake out a 100 km
long section of a 380 000 volt line in the middle part of Sweden by a
far reaching application of photo-interpretation and photogrammetric
plotting. Parts of the line have been photographed on scales between
1:4 000 and 1:40 000.
Some other photogrammetric measuring and recording methods,
mainly based on single pictures, are used in the hydraulic laboratory of
the Board.
The Organisation. The photogrammetric work of the State Power
Board is done in close collaboration with the Geographical Survey
Office, which carries out the requisite aerial triangulations, precision
plottings, and other more extensive mapping operations. At present
more than 10 of the Board’s officials are doing photogrammetric work
and many others are using aerial pictures for preliminary planning.
Principal Methods and Instruments. Besides the usual methods and
the already mentioned combination of Geodimeter observations with
photogrammetric measurements the State Power Board generally em
ploys a method based on a small scale aerial triangulation of high alti
tude pictures to determine control points, subsequently used for both
general mapping and the large scale triangulation of low altitude pic
tures. The small scale triangulations are often supported by bases fixed
on ice. Triangulations and precision adaptations are done at the Geo
graphical Survey Office in an Autograph A 7 belonging to the State
Power Board.
In order to delimit the areas to be plotted and rapidly investigate al
ternatives of projects, the State Power Board very extensively recon
noitres the latter in stereoscopic instruments, at the same time deter
mining altitude differences and distances far more accurately than can
be done by the usual geodetic methods during brief visits to the respec
tive places. Such reconnaissances in stereoscopic instruments are not
made, however, instead of field reconnaissances, but are an aid to make
them more effective and concentrated at the most important points. An
Autograph A 6 was formerly used for these studies of the stereoscopic
models, but nowadays a Kelsh Plotter is used. Mirror stereoscopes are
also extensively used for reconnaissances in connection with problems
of forestry, timber floating, erosion and road construction.
When a map is to be used in legal proceedings relating to claims for
damages, specially critical parts of it — e. g. where the ground slopes