lines, roads, buildings, drainage etc. is going on.
This map consists of a high quality controlled photo
mosaic printed in green with a superimposed print
in black showing all the abovementioned details
and a superimposed yellow tint printed on the
farmed land.
For military purposes 5-metre-contourlines and
a coordinate-grid are superimposed on the same
photomosaic and the map is thereafter printed in
a high quality half-tone-method. This map is gen-
erally not available for the public but may be used
for certain civil purposes.
The new topographic map on 1 : 50,000 (remote
areas on 1 : 100,000) is based on the two above
mentioned maps. The field reconnaissance for the
topographic map is combined with the field recon-
naissance for the cadastral map when possible.
When a coordination of the two maps is not possi-
ble a special stereoplotting in autograph A6 or in
Balplex is performed for the topographic map-
manuscript.
The methods for the production of the above
mentioned official maps is constantly improved. A
big step forward in the determination of rectifica-
tion points was made possible when the country
was photographed from 10,000 metres altitude
(scale 1 : 67,000) during the last four years in a
combined operation by the Swedish Air Forces and
the Geographical Survey Office.
Hydrographic Surveys
The hydrographic surveys of the vast coast- and
archipelago areas of Sweden have since fifteen years
been based on photogrammetrically determined
shorefixes and shorlines. During the last four-year-
period a completely new procedure has been devel-
opped based on a precision aerial triangulation of
the above mentioned photographs (1 : 67,000) in
autograph A7, electronically calculated coordinate
transformations and rigorously rectified dimension
stable photographs on a scale of 1:10,000 from neg-
atives taken from 4,000—5,000 metres altitude. The
hydrographic depth charts on a scale of 1 : 10,000
are not published but are used not only in the chart
editing but also as an important tool in planning
of fareways, harbours etc.
Legal surveys
The Land Survey Board has the main responsibility
for the legal surveys and produces with photogram-
metric stereo methods the base maps for reallot-
ments and for various planning purposes, mainly
for planning of urban and other densily populated
areas. The photogrammetric production of the Land
Survey is characterized of a well planned alternat-
ing work of the central photogrammetric organiza-
all over the country. The last mentioned are respon-
sible for the geodetic control surveys, the signaliza-
tion of controls and boundery points, the field in-
ventory of boundery lines etc. and the field com-
pletion. The organization in Stockholm does the
planning, keeps contact with the Geographical Sur-
vey Office, which performes the photography work,
makes the electronic calculations and adjustments
of the control net and makes the stereo plotting.
There has been found to be a distinct need for
photogrammetric standards in legal surveys similar
to the standards in force for terrestrially performed
work. A comprehensive work has been accomplish-
ed in this field but there are great difficulties to
reach a good solution. It has been regarded as very
essential that the standards should not hamper the
future development of the photogrammetric meth-
ods and also that the standards should not call for
checking surveys to such an extent that the profit
reached by photogrammetry is consumed in the
checking.
Base maps for urban and similar planning as well
as for other legal purposes are produced in the same
way by other governmental organizations and pri-
vate firms. Nowadays a special effort is made in
the mapping for highway-planning in order to en-
sure the fitness of the maps not only for the high-
way construction but also for the legal procedures
connected with the right-of-way problems.
Photogrammetry in civil engineering
The planning of building projects affecting the ter-
rain calls for adequate maps as well as information
on soil, rock etc., usually comprised in special maps.
When the project affects a large area and the ter-
rain renders possible alternative solutions the de-
mands on the maps increase. The Swedish terrain,
at an average rolling and forest covered, has been
glaciered and is consequently rather varying. The
good possibilities to fit the photogrammetric pro-
ducts to various requirements facilitate a step-by-
step planning and designing during which the de-
mands on accuracy etc. are successively increased
and the most accurate and expensive work can con-
sequently be restricted to the final alternatives.
H ydroelectric power planning
The hydropower resources in North Sweden have
normally fairly small drop, great flow, possibilities
to lead water from one river to another etc. which
make the number of solutions almost infinit in the
first planning stage. The terrain areas to be taken
into consideration are also very vast. Consequently
the Swedish State Power Boards has, during the last
decade, devoted a lot of interest and resources in
photogrammetric mapping of large areas in North
tion in Stockholm and the local district surveyors ;3i Sweden by its own photogrammetric organizations
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