-11- 
acy Phase B 
or 
1) Photomaps at scales 1:50,000 and 1:100.000 are assembled from the ortho- 
photos and can be published as first provisional maps. They can serve as 
43 base maps for resources surveys and also for the selection of areas of 
urable which larger scale photography is considereà necessary for topographic or 
rter other interpretation purposes, If desired, the application of pictomap 
procedures can also be considered at this stage. 
2) In an independent process, contours (contour interval 20 m) can be 
erval constructed and scribed, using the drop line charts. These contours can be 
printed over the first provisional (photo)maps. 
la- e e 3) According to priorities, the following stages of perfection can then be 
carried out for individual map sheets, in which photogrammetrio plotters are 
no longer required. 
em 
a) On larger scale aerial photography or on the original small scale photo- 
ly graphy under certain circumstances, a topographic office interpretation 
is carried out with the aid of simple mirror stereoscopese 
The results of this office interpretation are transferred to the original 
photomaps printed on scribing sheets and are used for the production of 
  
PS annotated photomapse 
‚ES b) The office interpreted aerial photographs are then used in the field for 
field identification and field completion. The results of this phase are 
l also transferred to the original photomaps and are either used for the 
jS production of a final annotated photomap or as desoribed in c). 
c) After cartographic eneralisation, the results are used for the produe- 
tion of a final multi-colour line-map at scales 1:50.000, 1:100,000 or 
1:250.000. 
e © 
A further improvement of the topographic map is possible, if, after establi- 
shing geodetic height control and after re-adjusting the network of 
APR-profiles to this control, contouring is carried out in photogrammetric 
plotters. In this case, a contour-interval of 10 m can be obtained, 
4. Comparative evaluation of cost and time requirements 
The cost and time estimates will be confined to & comparison of the production 
of line base maps (using the conventional system) and the production of photo 
base maps as indicated in phase A of the proposed system. The estimates are 
based on an area of 100 000 km“ and on the assumption that the final aim is 
2 to produce a topographic base map at the scale 1:50.000. 
0