390 
It 
—ITAttaA 
it toiim 
S.R. SLOVENIJA 
C.A. SRS 
PREGLEDNA KARTA 
KLIMATSKIH CON 
po 11. aprilu 
po 16. aprilu 
vz po 21.aprilu 
t¿1/sA po l.maju 
□ po 11.maju 
AVSTRIJA 
Figure 5. Regional division of Slovenia according to starting dates in dependancy of climatic conditions. 
between 1 : 15 600 and 1 : 19 150. 
For intensive plane areas the aerial survey is re 
alised in the scale 1 : 10 000 and is used for revi 
sion of topographic maps in scales 1 : 2880 and 1 : 
2000. Camera is Zeiss with c - 305 mm with image mo 
tion compensation which contributes to greater reso 
lution and accuracy. 
The main cycle is 3 years covering each year appro 
ximately one third of the entire teritory. Permanent 
aerial survey enables high qualitiy of final product 
and greater flexibility for user needs. Cycle of 3 
years is usefull at the following works: 
- cyclic revision of topographic maps and plans 
- maintenance of spatial data bank 
- elaboration of planning documentation 
- elaboration of urban and rural plans 
- photointerpretation of forestry components 
- elaboration of photo mosaics and photomaps. 
The time for the realisation of aerial survey runs 
from april to august. The starting point is defined 
by the spring vegetation step, climaticaly given by 
10°C of average daily temperature. Since the Slove 
nian territory is not climaticaly homogenous it is 
not possible to unify the starting point. The aerial 
survey is there fore different for different geograp 
hical locations and starts 2 to 3 weeks after vegeta 
tion starting point. This enables the optimal time 
period for agricultural vegetation. 
For the metric restitution of the photographs addi 
tional signalisation of geodetic points is realised 
which gives greater accuracy of elaborated plans and 
maps. 
The cyclic aerial survey is financed by 81 users. 
The quality and additional proposals for survey is 
realised through users board having a meettings once 
a year. The cyclic aerial survey is economicaly spe 
aking for about 20 % less expensive then aerial sur 
vey upon order. This is the result of systematic ap 
proach and the continuity of the realisation. 
Practical experiences 
The present system of cyclic aerial survey started 
to be operational from 1975. The film Agfa Gevaert 
Pan 200 has been used in order to increase the re 
solution between different kinds of vegetation (in 
near infra red). Combination with narow angle and 
image motion compensation gives the photographs of 
good qualitiy, being extremly usefull in forestry 
and agriculture. It is evident that better results 
would be reached by IR films, which is at the moment- 
not realiasable due to financial and technical pro 
blems (the present techniques do not allow mass pro 
duction of coloured contact copies and enlargements). 
The advantage of cyclic aerial survey is at perma 
nent availability of photographs which is not the ca 
se at the aerial survey by order. The main disadvan 
tage of the cyclic aerial survey is its unability to 
meet the user special requirements in full extent.