4 
In the deiinition of pass points by both geodet- 
ical methods and aerotriangulation, the limits of per 
missible mean planimetric errors are as follows: 
for maps on a scale of 1:5000 ±0.25 m, 
for maps on a scale of 1:2000 ±0.11 m. 
for maps on a scale of 1:1000 ±0.07 m. 
The Technical and Economic Maps on 1:2000 
and 1:5000 scales are graphically plotted point by 
point, the coordinates of some points (trigonometric 
al network, polygonometric points, pass points and 
some other points intended for the supplementary 
surveying of unplotted spaces) being registered. Maps 
on the scale of 1:1000 are plotted numerically, the 
registered model coordinates are transformed into 
geodetic coordinates, and the original is drawn by 
plotting all points on an automatic coordinatograph. 
If the photogrammetric methods is used, the build 
ings are represented by the projections of their roofs. 
The following mean planimetric errors are characte 
ristic of the accuracy attained in the photogrammetric 
plotting of the planimetry: 
in maps on a scale of 1:5000 ±0.50 m, 
in maps on a scale of 1:2000 ±0.25 m, 
in maps on a scale of 1:1000 ±0.15 m. 
In maps on all of these scales, the altimetry is 
in both flat and hilly country photogrammetrically 
plotted with the principal contour lines spaced at 
one-metre intervals. 
A total area of 2800 km 2 was photogrammetric 
ally plotted (most of it on a scale of 1:2000) for 
large-scale technical maps, during the period of 1964 
to 1967. 
3. Photogrammetry in Forestry 
Photogrammetry is finding an extensive field in 
forestry mapping and re-allotment work, for both 
surveying and interpretation. Forests cover about 
34 %, that is some 4,400,000 hectares, of Czecho 
slovakia’s national territory. A considerable part of 
this area needs re-mapping to supply forestry with 
the kind of map it requires. In addition to this re 
quirement for basic forestry maps, re-allotment work 
calls for forest crop maps representing the dynamics 
of forest husbandry with a satisfactory degree of ac 
curacy. They have to show the local data referring to 
stands and growth on which assessments are based. 
Two kinds of situations must therefore be distinguish 
ed on forestry maps — the so-called basic situation, 
of a stable nature, mainly showing boundaries and 
the economic and traffic network; and the growth 
situation, consisting of the variable details of the 
stand and directly affected by economic activities. 
The basic forestry situation has to be surveyed 
with a higher degree of accuracy, answering the re 
quirements of 1:5000 mapping and the special pur 
pose of forestry maps. Analytical and analogue meth 
ods of photogrammetry are used to this end. Both the 
photogrammetric and geodetical point fields are ob 
tained by analytical strip aerotriangulation, and the 
base maps are plotted on universal photogrammetric 
plotters. Successful experiments with the analytic 
aerotriangulation of those point fields in general 
blocks are in progress. These methods of analytic 
photogrammetry combined with machine computation 
should enable us to re-map Czechoslovakia’s forests 
within 30 to 40 years without affecting other tasks 
which photogrammetry has to fulfil in the re-allot 
ment of our forests. 
The variable details of stand or crops have to be 
re-mapped every ten years in accordance with the 
production and management plans on which orderly 
exploitation is based. Without efficient photogram 
metric methods it would hardly be possible to deliver 
those maps in good time and in the requisite quality. 
The interpretation of aerial photographs plays 
an important part in all these activities, beginning 
with the surveying of the stand, which depends on 
interpretable crop photographs. On black-and-white 
photography, the hues, the structure and the spatial 
impression are the main indices. Apart from the per 
fect orientation in the field, the technicians respons 
ible for the assessment on the spot use the aerial pho 
tograph primarily for choosing and adjusting their 
tracks covering the wooded ground, for estimating 
the density of the forest, and as an aid in making and 
correcting their assessment. In the near future we in 
tend to make experimental use of special photogra 
phic materials — colour material, false-colour films, 
etc. — for easier interpretation of aerial photographs. 
4. Single-Purpose Mapping 
The rapid development of our national economy 
calls for growing numbers of single-purpose maps. 
Traffic projects, agriculture, mining, hydraulics, and 
forestry (the latter treated separately in this report) 
are the most important fields for which such maps 
are required. For illustration we quote some applica 
tions of photogrammetry to these branches of eco 
nomy: 
Traffic reconnaissance and planning — permanent 
ways and railway stations plotted for document 
ary information on a scale of 1:1000 (Standard 
Railway Plan); photogrammetric measurement 
of longitudinal and cross profiles of roads (for 
planning and design purposes); plans for recon 
struction projects on railways and roads. 
Agriculture — 1:2000 mapping for land improve 
ment projects, with strict demands on the photo 
grammetric plotting of altimetry. 
Mining — photogrammetric measurement of over 
burden moved in opencast brown-coal mines; 
photogrammetric investigation of subsidences in 
mining areas. 
Hydraulics — terrestrial photogrammetry employed 
to plot the contour plans of drained reservoirs 
before reconstructing the dams. 
5. Special Applications 
In most cases of this description, aerial or terres 
trial photogrammetry is used for surveying large 
numbers of detail points, frequently ineccessible, or to 
obtain numerous precise data in circumstances where 
classical surveying methods are either inapplicable or 
at least difficult. Photogrammetry has extensive fields 
of application, for such purposes, as indicated by the 
following examples: