B7:= 5-8 +ei +10 +13 + 14 
BE f Header 10:+:+13; + 14 
BY = 4.10 + 18 + 14 
For the screening of printing original No. 1, a 60 dot screen has been used. Since coated 
art paper is not well suited for subsequent cartographic entries, "map paper' has been used for 
printing. 
The third test on the preparation of a topographic photo map 1:25.000 has been performed 
according to Printing Process C. Of the possibilities indicated, one has been realized. The fol- 
lowing version of the map sheet "Dillenburg' is available : 
Cl.=19 +1 +.15 + 1*8. 1910-0513: 14 
This version is attached as enclosure. For the screening of the printing originals No. 1 
and No. 15, a 60 dot screen has been used. 
Printing has been done on ''map paper''. Although the colouring of version C1 differentiates 
considerably of the comparable version Al, it still does not correspond to the aim aspired after. 
Due to the relatively high range of contrast of the aerial photograph original, version C1 is alto- 
gether too dark i.e. the graphic density per unit area is in the darker parts of the map sheet too 
high. In other words : the forest areas should be kept lighter without reducing, however, the con- 
trast of the field areas and the built-up areas. Evidently this demand can only be fulfilled if the 
printing original No. 1 (aerial photograph) can be accordingly treated by a phototechnical contrast 
adjustment and contrast increase. In the tests performed so far, analoguous procedures of image 
processing have only been applied to a limited extent. It must still be clarified, too, whether the 
red colour chosen for the road mask serves its purpose or whether a pure yellow colour would be 
more suitable. It is understood that with a version determined for practical use, additional names 
and designations would have to be entered into the map sheet. But as we are primarily concerned 
with deloping a procedure on the preparation of a topographic photo map, this is only of minor im- 
portance. In conclusion be mentioned, that some copies of the version C1 have under the same 
conditions also been printed on coated art paper. On this paper, the single colours (in particular 
the yellow colour for the field areas, and the green colour for the forest areas) seem purer than 
the colours printed on "map paper', this increasing the expressiveness of the map. 
4. - Revision of Topographic Photo Maps 
  
Nowadays, the procedures of preparing and revising (updating) a map series are primarily 
judged by the attainable accuracy and the required expenditure of time. The (planimetric) accuracy 
of the enclosed map sheet ''Dillenburg' corresponds in all probability to that of the Topographic 
Map 1:25.000 (line map) of the Federal Republic of Germany, as can be gathered from the tests 
performed so far. Thetime spent for preparing the map sheet "Dillenburg' according to printing 
process A amounted to approximately one month (incl. print order). This information shall only 
serve as general characterization of the procedure applied by us to prepare a topographic photo 
map. As to the revision of topographic aerial photographs, we can so far only state that its per- 
formance should be relatively simple considering the fact that a new orthophoto plan (i.e. a new 
printing original "aerial photograph") can be prepared at any time from the latest aerial photogra- 
phy available by means of the measured and stored terrain profiles [6], [7]. 
9. - Concluding Remark 
  
The tests performed on the preparation and revision of topographic photo maps 1:25.000 
have not yet been concluded. For this reason, only an intermediate report can be given. Apart 
from an improvement of the colouring and an increase in the topographic expressiveness of the 
photo map, we shall also have to investigate whether coloured aerial photographs, image recor- 
dings of remote sensing technics and the application of digital image processing procedures render 
possible an improvement in the preparation of the printing originals and an increase in the topo- 
graphic expressiveness without considerably increasing the manual portion of the working time. 
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