105 
points per second and do not cope with the registration accor 
ding to the profiling speed# It Is even worse if during profi 
ling time we would like to register the full digital model 
terrain# It means three coordinates X,Y,Z# The magnetic recorder 
Titu-Dygidata can register only one point during 0,7 second# 
It means that it can secure the recording only during the non 
automatic profiling# 
Reliability of system performance 
is a very essential economic parameter# Defect or faults of 
the instrument disturb orthophoto production cycle and decease 
to a considerable degree the production efficiency of the system# 
Therefore it is important to seoure careful maintenance of the 
instrumentation, and what is even more important to have the 
staff which is able to repair the defects# 
4» Time and cost of orthophoto production 
Krauss and Pape [3] present an interesting table showing the 
requirement of time and cost needed for the production of one 
sheet of orthophotomap at the scale 1:5000 /4 square km/ using 
"off-line" system with C-8 Zeiss stereoplan!graph equipped with 
SG-1 storage unit and G2-1 ortoprojector# Prom table 2 one can 
find out about the time and costs involved in the production of 
a 1:5000 orthophotomap# The following cases can be considered: 
A - only horizontal situation /without contour representation/* 
Then total time is 5*5 days, and cost 1890 - D#M# including 
work pointed out at 1, 2b, 4# 6 and 10# 
B - orthophotomap including contour representation /based on 
dropped lines/ according to thh type of work shown in 1, 2b, 
5, 6, 7, 9 and 10, total time 13*7 days and 3120 D#M# costs# 
C - orthophotomap including contour representation /which was 
obtained from HLZ contourliner/ and type of work mentioned 
in 1, 2b, 5# 6, 9 and 10# Total time 9*7 days and cost 
2620.- D.M. 
D - orthophotomap including contour representation /by means 
of stereoplotting/ according to the type of work pointed 
out at 1, 2a, 3, 4, 6, 3, 9 and 10# Total time 17*5 days 
and costs of 5090#- D#M# 
The same German Base Map compiled by the stereoplotting technique 
takes about 75 work days and costs 18000#- D#M# Even in compa 
rison with the most expensive case /D/ it can be seen that ■che 
cost ratio is 1:3*5 and the time - consuming ratio is 1:4*3* 
In the alternative pointed at C these ratios are respectively 
1:6 # 9 and 1;7*7*