102 
The system of production of orthophotoi "on-line” or "off-line” 
is another important factor which influenced the instrument 
construction and profitability of orthophoto procedure# The 
production line of the company decides about the orthophoto 
instrumentation# When this instrumentation has to be a supple 
ment of the existing photogrammetrie equipment, then simple 
and unexpensive instruments working together with plotters in 
"on-line" system should be chosen# But if orthophoto instru 
ments can be an essential and independent equipment, then more 
expentive compicated and multifunctional orthophoto devices 
should be used, which in "off-line" system can be applied# 
If we accept orthophoto as a document in the process of map 
compilation, then we can accept also stereoorthophoto as a 
technology more versatile and more universal# Therefore in 
the construction assumptions of the orthophoto instruments 
the aspect of simultaneous production of orthophoto and stereo 
mate should be also considered# 
The second factor determining the adaptation of 
orthophoto instruments to the quality of orthophotomap produc 
tion is connected with the assignment of produced orthophoto 
graphs# In France, for instance[1,2] , orthophotos an a small 
scale 1:40000 to 1:20000 are used to search of the phenomena 
taking place on large regions# Orthophotos on the scale 
1:20000 and 1:10000 are helpful in cartography during the 
production of thematic maps in mountains areas# Orthophoto 
maps on the scale 1:10000 and particularly on the scale 
1:5000 are use for different purposes and, among others for 
planning inventory, cartography, engineering study or prospec 
ting in geology# Large scale orthophotomaps /1:2000/ are use 
ful in urban planning, highways and pipelines projects, in 
land inventory and land integration projects and many others# 
Orthophotos can be now also used as indirect documents to line 
map compilation and for x periodical map revision# 
Orthophotos supplied with onomatology, counter-lines and carto 
graphic net present the final form and can replace the line- 
maps# 
The third factor is connect eel with required accuracy 
of orthophoto# The accuracy depends on: 
1/ orthophotoscope construction, 
2/ adjustment of the plotter and orthophoto instrument, 
3/ photogrammetrie measurements v conditioned by the quality of 
instruments and the operator s experience, 
4/ quality of initial data and selection of photographic mate 
rial and procedure# 
Well performed orthophoto secures the accuracy between 0 # 1 mm 
to 0,2 mm [4] • But not always such accuracy is necessary# 
Recognition done by the Institut Géographique National in France 
[2] indicates that nearly all orthophoto users /90%/ are safis- 
fied by the 0,5 mm accuracy# The others /10$/ demand eith er isj 
higher or lower accuracy# We can see that in this case it(not 
diffiouli to satisfy the orthophoto receivers# In 3pite of such 
low accuracy demands some users are dissatisfied with certain 
degradation of orthophoto pictures in comparison with original