external description. The content of topographic map 1:5000 is 
very extensive and applicable in many activities and economic 
fields. The map is therefore called Croatian Base Map (HOK, 
earlier State Base Map, abbreviated ODK). The unique way of 
presenting the content is secured by the cartographic key. The 
printed copies are distributed to possible users, and only a part 
of the edition, along with the original copies, is kept in the state 
institution authorized for geodetic and cadastral work. It is 
actually the only topographic map that is produced system- 
atically in Croatia (Fig. 2). 
Today, HOK is produced on the basis of aerial photography at 
the scale of 1:10 000. The sheets are made in digital form with 
the program support of the firm Microstation. The topographic 
content is saved in the format DGN/DXF, and the relief 
presentation is done in SCOP-DTM. 
According to the Program of the State Survey and Real Estate 
Cadastre for the Period 2001-2005 (Hrvatski drZavni sabor, 
2001) there will be 1028 sheets of HOK controlled and printed, 
859 sheets will be made and 500 sheets updated in digital form. 
All 9821 sheets will be transformed into the TIF format. 
2.2 Topographic maps at the scale of 1:25 000 and smaller 
produced on the basis of topographic survey between the 
two world wars 
The Military and Geographic Institute from Belgrade was 
carrying the topographic survey at the scale 1:50 000 in Serbia, 
Monte Negro and Macedonia from 1920 till 1928. For the 
territory of Croatia, Slovenia and Bosnia and Herzegovina 
which were the parts of Austro-Hungarian Monarchy, there was 
a very good map of the Military and Geographic Institute in 
Vienna at the scale of 1:75 000. For these areas the content was 
updated in the period from 1929 till 1933, and the originals of 
Austro-Hungarian survey were used for compiling the original 
copies in the scale of 1:50 000 (Franéula, 2000). 
On the basis of the field original copies, the Special Map of 
Yugoslavia was made at the scale of 1:100 000 in polyhedric 
projection. The initial meridian was the Paris one. The map 
consisted of 197 sheets the size of 30'x30'. Since 1931 this map 
has been published at the scale of 1:50 000 as well. 
On the basis of topographic survey made from 1934-1939 there 
were 208 sheets made for the map 1:25 000, i.e. 118 sheets for 
the territory of Slovenia, 52 sheets for the territory of Croatia, 
and 38 sheets for the territory of Serbia. The map was made in 
GauD-Krüger projection, but the format and the sheet division 
were adjusted to the maps of the Military and Geographic 
Institute at that time, i.e. the initial meridian was the Paris one, 
and sheet dimensions were 7'30"x7'30". 
The Military and Geographic Institute (VGI) in Belgrade 
monopolized the production of topographic maps in medium 
and small scales, as well as of general topographic maps needed 
in economy and administration, as long as after the end of the 
World War I. In 1938 VGI introduced photogrammetry pro- 
viding adequate photogrammetric instruments and equipment 
with the help of the firm Zeiss, for aerial photography, as well 
as for restitution. In that time, it was the most sophisticated 
photogrammetric technique. This technique helped the first 
topographic maps to be produced by means of photogrammetric 
method. The testing gave satisfying results, and the photogram- 
metric method was accepted as the basic method of topographic 
land survey (Stosié, 1969). During the World War II, VGI was 
164 
ruined together with the photogrammetric instruments and 
accessories. After the World War IL, the Main Geodetic 
Administration of FNRJ of that time and VGI initiated the 
introduction of photogrammetric method of land surveying 
again. 
In the period from 1945 till 1951 the topographic map at the 
scale of 1:200 000 was made. The basic source for this map was 
the Special Map at the scale of 1:100 000 that was revised in 
1946. This map was also made in polyhedric projection with the 
same sheet division as the other maps. 
The division of the above stated topographic maps takes the 
map sheet 1:200 000 as its basis. Each sheet contains 4 sheets 
of the next larger scale. Apart from their name according to the 
most famous settlement or geographic object on that sheet, the 
topographic maps 1:100 000 and 1:200 000 also got their own 
number. The numbering is made following the rows from the 
north to the south, and in a single row from the West to the 
East. The sheet of the map 1:50 000 bears the name and the 
number of the accompanying map sheet 1:100 000 with an 
additional designation 1, 2, 3 or 4. The map sheet 1:25 000 also 
has an additional designation a, b, c or d apart from the above 
mentioned ones. 
The graticule is usually not delineated within the sheet frame of 
topographic maps. There are several reasons for it. Meridians 
and parallels are mapped as curves in most projections. Even if 
mapped, the curves may be replaced by straight lines, the 
obtained figure bordered with two meridians and two parallels 
has got neither the shape of a rectangle nor of a square, but of a 
trapezium. The mapping of points or reading the coordinates on 
the basis of coordinate lines of such a shape is not easy. In 
order to facilitate such tasks which are very frequent when 
working on topographic maps, the grid is delineated on all 
topographic maps. This is a system of mutually perpendicular 
lines on a map, that parallel to coordinate axes at the selected 
equal distances. 
Since each sheet is a unit for itself in polyhedric projection, 
there is no unique projection coordinate system that would 
connect all sheets into an entity. This is a very large 
disadvantage of polyhedric projection. VGI decided therefore in 
1931 to introduce the grid of GauB-Krüger projection onto the 
topographic maps in polyhedric projection that was adopted in 
1924 to be used in state survey of the Yugoslav territory. On 
that occasion, a question came up: how much will the grid of 
the GauB-Kriiger projection mapped onto the map sheets in 
polyhedric projection will be distorted? The tests showed that 
the distortions of grid lines were smaller than the graphic 
accuracy and therefore they could be neglected. Thus, the 
GauB-Kriiger projection of the fifth, sixth or seventh system 
was introduced onto all sheets of the maps at the scale of 
1:50 000 and 1:100 000. 
The sheets of these old topographic maps in polyhedric 
projections at the scales of 1:50 000, 1:100 000 and 1:200 000 
are still used. Namely, some thematic contents of a more lasting 
value (e.g. pedology) were processed on these maps, so we will 
encounter them in practice for some time. Only the copies 
printed on paper are still in use. Publishing sources of these 
maps are not available. 
  
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