6 Finland 
stereoscopically using 1 : 10 000 reduced cadastral and register maps. The pre 
interpretation of planimetrie details is done at the same time on stereo pictures. 
The inventory in the field comprises checking and supplementing plani 
metrie details, contour lines, property boundaries and names. 
The final drawing of the Basic Map is done on the scale of 1:10 000 on 
plastic sheets from the field drawings. Planimetrie details, contour lines and 
other elevation information and property boundaries are drawn on separate 
sheets. There is a trend to go over to scribing which method is already applied 
for contour lines. The text is prepared mainly in photosetters and it is fixed 
with stripping-film. After several proofreadings the Basic Map is printed in six 
colours on 1 : 20 000 scale in offset press. Different kinds of copies of the map 
on 1 : 10 000 are available on request. 
At it can be seen in the Table in 1963 contour lines of the 1 : 10 000 map 
were drawn with A 8 and B 8 plotters over an area of about 11 000 sq.kms. The 
annual output of the Basic Map covers about 15 000 sq.kms. Thus the contour 
lines over an area of about 4 000 sq.kms were established using the Classical 
Field Method with stereointerpolation. 
Topographic Map 1 : 20 000 / 1:100 000 
The sparsely populated areas in Northern Finland are mapped directly on 
1 : 20 000 scale by both the National Board of Survey and the Army Map 
Service. 
Aerial photography is done with wide angle cameras on 1 : 30 000 or 
1 : 60 000 scale and the extension of ground control with Zeiss Stereoplanigraph 
using the Elevation Controlled aerotriangulation. Geodetic triangulation or 
traverse nets with 1 — 2 points/100 sq.kms. measured with Tellurometers and 
theodolites are used as the basis. Elevation measurements are carried out partly 
by levelling and partly tachymetrically. 
Stereoplotting is done with Autographs A 8 and B 8 as well as with 
Stereotope instruments, depending on the importance of the area concerned. 
Contour lines at intervals of 10 meters and most of the roads and watercourses 
are plotted with stereoinstruments on the scale of 1 : 20 000 on the same 
plastic sheet. 
The aerial photographs are rectified to 1 : 20 000 scale by means of rectifica 
tion data obtained from the aerial triangulation or with the aid of control points. 
In most cases the rectified pictures are cut and composed into stereopairs. 
The pre-interpretation is done stereoscopically on paper prints or on rectified 
film-diapositives. If an aerophotographic map of 1 : 20 000 is available, the 
results of the interpretation are recorded on a Correctostat copy of it. If not, the 
planimetrie details are recorded on the contour drawing using roads, watercourses 
etc. for matching. Checking of pre-interpretation, collecting of names, classifica 
tion of roads and recording of dwellings are done in the field. The use of a 
helicopter in the inventory of the terrain has been experimented with and the 
first results are promising. 
The final drawing of the Topographic Map (1 : 20 000) is done by scribing 
and by drawing on two separate plastic sheets, the planimetrie details are 
recorded on one and the contour lines on the other. 
The map of 1 : 20 000 is printed in three colours, with the texts and 
planimetrie details in black, contour lines and main roads in brown and 
hydrography in blue. 
The map 1 : 20 000 is drawn so roughly that, if necessary, a map on a scale 
of 1 : 50 000 can be prepared from it by photographic reduction. Test sheets 
of this map on 1 : 50 000 scale and in five colours have been printed mainly 
for military purposes. The material of the map 1 : 20 000 is mainly used for 
compiling the topographic maps of 1 : 100 000.