448 
dastral and planning maps have to be digitized completely. They have to be reviewed 
and completed by those points, being visible in the phatographs. Those areas with an 
already existing coordinate cadastre can take that over into the LIS. 
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Fig.8: Presentation of parcel boundaries combined with a hedge in a photograph and 
the map. 
- topography 
The topography in existing maps is not paid that much attention to as it should be in a 
- LIS. By use of colour diapositive film it is possible to collect all topographic data with 
the analytical plotter. 
- utility 
The visibility of utilities in the aerial photograph is quite different. Primarily it depends 
on the difference between an overhead line and a subterranean one. Overhead lines are 
clearly visible and can be measured with the DSR-1. But in this case, the relation to 
the correct linetype (symbol) is often diffi cult. Therefore the undefined levels are used 
and will be changed interactively during the final treatrnent. 
The secondary group consists of those utilities with quite a number of visible details on 
the surface. being connected by pipes. Generally those utilities are water-, sewage-. 
rainwater-sewage- and gas-pipes. 
The most difficult kind of utilities are those being connected by cables like telephone 
and cabl e-TV. Visible facilities. like hatches. are seldom to be found and connecting lines 
are not always straight. In those cases. the lines themselves have to be digitized from 
graphical sources and have to be reviewed by measured distances. 
Alghough a colour diapositive film was applied, plenty of superficial details are not’ 
visible because of their size or their similarity to their surroundings. 
Therefore those details have to be signalized. 
Together with the existing maps it is much easier for the operator to find small details 
of the utulities. because they enable him to know where to look for them. In addition 
but only for this performance. sites of road works are other good advices (see fig.7).