Sweden 10
One or two additional autographs — one Wild A 7 from the Institute
of Technology and one Wild A 5 from the General Staff — are rented
at an average rate corresponding to one instrument a month for 8
months a year. In the spring of 1956 a new Wild Autograph A 7 will
be delivered to the Central Office.
Planimetric details and contours are mainly plotted graphically by
stereoplotting separate models. In rare cases coordinates of boundary
points have been determined.
The ground control networks have been supplemented by stereoplot
ting separate models and by aerial triangulation. Many different pro
cedures have been tried especially for re-allotments. It has been found
that the situation of a large number of usually signalled points on the
ground can be determined photogrammetrically directly from a geode
tic triangulation network, and also that geodetic measurements can be
taken from such photogrammetrically determined points. Many exten
sive traverses or stake line networks have been avoided in this way.
It has frequently proved possible to combine the purely technical
plotting work with photo-interpretation, which simplifies older methods
and saves both time and money. Photo-interpretation is accordingly
used mainly for planning purposes and ground appraisals. See [79].
The National Hydrographic Office*)
Photogrammetry is used by the National Hydrographic Office for
producing line maps, so-called ’’original” sheets, on the scale of 1:10 000
and the sheet size of 50 X 50 cm, on which the hydrographic symbols
are explained. The plotted hydrographic original sheets are produced
by stereoscopic adaptation in precision instruments. This includes the
plotting of shore lines, minor control points for later hydrographic mea
surements, and contour lines at 5 m intervals.
The photogrammetric work is done at the Geographical Survey Of
fice with the assistance of hydrographically trained personal from the
National Hydrographic Office. In the period 1952—1955 an area of
2 325 km 2 has been plotted in this way.
Airborne Mapping Limited
Airborne Mapping Ltd started work in 1952 and in 1954 granted
permission to fly for air survey photography.
The company is organized in close co-operation with AB Jordbruks-
flyg (Agricultural Flights Ltd), which has developed the use of light
aircrafts for agricultural and forestry purposes and also does prospect
ing work in intimate collaboration with Lundberg Explorations Ltd.
*) Since 1/1 1956 this Office is a department of the Board of Shipping and
Navigation.
