390 
PRELIMINARY REMARKS AND POSING THE PROBLEM 
In the FRG do exist about 65,000 sheets of the German Basic 
map 1:5,000. They are printed in two colours, black for the 
planimetry representation and the characters and sepia- 
brown for the contour-lines. For each sheet in the modern 
edition we have three cartographic originals, one for the 
planimetry representation, one for the characters and one 
for the contour-lines. 
In some areas, especially in city areas, we can get digital 
geometric data by the coordinates of the cadastral boundary 
points and of the house corners, which are stored for our 
digital cadastral map. But in the larger part of the FRG we 
have no topographic data in digital form. So we have to 
digitize existing topographic map originals. 
For the quantity of map sheets at the scale 1 :5,000 exclu 
sive manual digitization has no future. At that time we 
would prefer a combination of manual and automatic digi 
tization. So it is the topic of our investigations to look 
for practical solutions with existing hard- and software. 
A well-known problem of the application of automatic digi 
tization by means of a raster-scanner is the subsequent 
conversion from raster-to-vector - if vector data are 
desired - and the feature-tagging. It was our main objective 
to perform these processes as much as possible in batch 
processing. But if there are economic or time-consuming 
advantages in a manual or interactive procedure, we would 
like to integrate it. 
Because of the great importance for several purposes there 
do exist a great number of software systems (partly hard 
ware-systems too) for the automatic raster digitization of 
contour-line-originals and the subsequent raster-vector 
conversion. So it was not a problem to scan the contour- 
line-original of our test sheet of the German Basic map at 
the scale 1:5,000 and to convert the data from raster to 
vector form. We used the ARLIP- System (Woetzel 1977). 
With this software-system developed by the Gesellschaft fur 
Mathematik und Datenverarbeitung (GMD) - Bonn, FRG - some 
years ago, a workable program has been made available for 
topological skeletting and line- and node-extraction from 
binary images. Experiments made with feature-se1ected 
cartographic originals turned out quite promising. A very 
important restriction is, however, that different qualities 
of lines and areas are not recognised automatically. For 
this reason atuomatic digitizing by means of raster- 
scanners is confined to so-called feature-se1ected graphic 
representations which are graphic scanning originals 
containing only one line quality (e.g. only contour-lines 
or only boundary-lines of the same quality). This restric 
tion is a great handicap for the general usage for carto 
graphic scanning originals because - apart from a few 
exceptions (e.g. contour-line-original) - cartographic