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3.5. Cadastral Information 
Orthophotomaps at scale of 1:2000, 1:5000 and 1:10 000 
serve mainly as a basis of the rural cadastre. Maps at 
scales of 1:1000, 1:500 and 1:250 serve as a basis of 
urban cadastre. 
A cadastral information system is created for about 20 
thousand sq. km of the territory of Bulgaria and for 
another 30 thousand sq. km input cadastral data are 
collected to be entered into the system. The main 
products of the cadastral information system are about 
20 types of balances which contain summarized data on 
definite indicators for each object. For those communes, 
for which an informational system is created (1896 of the 
territory of the country) 8096 of the data necessary for the 
land reform are available. The cadastral maps included in 
an information system, are ready maps of the land and 
serve as a basis of the land reform. 
3.6. Land Consolidation Maps 
For the needs of the land consolidation which began in 
1911 but was carried out on a mass footing in Bulgaria 
during the period 1932-1942, land consolidation maps at 
scale of 1:2000 are compilated for some lands with total 
area of about 1,5 thousand sq. km. 
4. LARGE-SCALE TOPOGRAPHIC MAP 
4.1. Aim and Purpose of Use 
The compilation and the periodic revision of the large- 
scale topographic map is assigned by the Bulgarian 
Government to the Main Department of Cadastre and 
Geodesy at the Ministry of Regional Development and 
Construction. 
For the intensive activity regions of the country it is made 
at scale of 1:5000 and for the unintensive ones - high 
mountain and forest regions - at scale of 1:10 000. Maps 
at scale of 1:2000 are made for special purposes to the 
order of separate users, mainly in the industrial regions. 
The large-scale topographic map aims at representing 
the location, form, dimensions and crops of the separate 
units and all situation details and objects, visible within 
the map scale, all hydrographic and transport objects and 
Structures, as well as the terrain relief. 
The large-scale topographic map is intended for the 
investigation, designing and planning of economic 
activities, for the solution of research problems as well as 
for defence. It is used as a basis for the preparation of 
thematic cartographic products. 
The content and scale of the topographic map is 
determined in accordance with the purpose of its use in: 
agriculture, forestry, geological surveys, hydrographic 
and hydromeliorative construction, regional development, 
environment protection, rural cadastre, etc. (Instruction, 
1985). 
439 
4.2. Coordinate System, Sheet Division and 
Nomenclature 
The large-scale topographic map is produced in 1970 
Coordinate System, introduced for the entire territory of 
the country. The Baltic Sea Level Datum serves as basis 
for the altitudes. The sheet division is done in a 
Cartesian coordinate system and all sheets, irrespective 
of the map scale, have frame of 50x50 cm. 
The sheet division is connected with that of the map at 
scale 1:100 000. Each map sheet at scale of 1:100 000 
is divided into 4 map sheets at scale of 1:50 000, into 16 
map sheets at scale of 1:25 000, as well as into 64 map 
sheets at scale of 1:10 000 and 256 sheets at scale of 
1:5000. The sheet division at scale of 1:2000 is 
connected with the map at scale of 1:10 000, where 
each map sheet is divided into 25 map sheets at scale 
of 1:2000. 
The nomenclature of the map sheets at the diSerent 
scales is connected with the nomenclature of the map 
sheet at scale of 1:100 000 to which Cyrillic letters and 
numerals are added. 
On the sheets at scale of 1:10 000,1:5000 and 1:2000 a 
Cartesian coordinate net is plotted at intervals of 10 cm. 
The coordinate net, the corners of the map sheets and 
the geodetic points are plotted with accuracy of 40.05 
mm. The admissible deviations of the measured 
distances between the sheet corners from their 
theoretical values are: + 0.3 mm for the sides and + 0.4 
mm for the diagonals. 
4.3. Geodetic Basis 
The following geodetic networks serve as a basis of the 
large-scale topographic map: 
(i) The national triangulation network from | to IV class 
and the local triangulation and polygonometry; 
(ii) The national levelling network from | to Ill class, as 
well as the triangulation points of known heights. 
The triangulation points and bench marks provide the 
geometric relation between the map and the terrain. The 
triangulation points are evently distributed so that there 
are 4 to 6 points on average in one 1:10 000 map sheet; 
1 to 2 points - at scale of 1:5000 and 1 point in 1 to 1.5 
sheets at scale of 1:2000. 
4.4. Contour Interval 
The relief is presented in contours, symbols and spot 
heights. For the scale of 1:10 000 the contour interval is 
1,2, 5 or 10 m; for the scale of 1:5000 it is 1, 2 or 5 m; 
for the scale of 1:2000 -1 or 2m. 
For each map sheet a uniform contour interval is taken, 
dependent on the predominant terrain slope. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996