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Orthorectificatio 
mage Processin 
Computer network including 
  
  
Silicon Graphics Indy 
Sun Sparkstation 20 
Pentium - Rechner 
  
Software 
OrthoMax (Autometric) 
IMAGINE (ERDAS) 
ARC/INFO (ESRI) 
Arcview (ESRI) 
Software development 
for merging raster and 
vector data 
  
  
  
  
  
Fig. 1: Hardware and software environment for the processing of aerial photography. 
Digital stereo photogrammetry has the advantage over 
analytical photogrammetry that nowadays many 
processing stages are handled automatically. At present, 
various companies are developing programs for fully 
automated triangulation of image blocks. The first 
operational solutions can be expected this year. 
A central component of our relief acquisition is a highly 
developed process of automatic image matching for the 
measurement of three dimensional grids of any density. 
Algorithms for the semi-automatic recognition of 
topographical objects such as roads, buildings and 
waterways offer an important step towards the 
automation of line measurement. Initially, there will only 
be isolated solutions for specific objects in this field. In 
the medium term, however, analytical photogrammetry 
will be replaced by semi-automatic systems. 
Visualisation and control of three-dimensional data 
components are of central importance to the stereo 
workstation. 
Generation of orthoimages is becoming increasingly 
important as the costs have decreased markedly by the 
digital rectification of aerial photographs into map 
317 
projections. The use of digital orthophotos for updating 
existing spatial data is evidently spreading. On screen 
digitizing in an orthophoto on a powerful pentium PC 
under Arcview is an inexpensive updating method. 
Image processing offers a wide range of possibilities. It 
is used for image preparation, the classification for the 
production of thematic maps and for the processing of 
three dimensional point data in a raster format. Only at 
this level it is possible and viable to process up to 1 
million points per square kilometre to form a relief model. 
A Geographic Information System for data storage and 
the analysis of the vector data obtained is indispensable 
in the field of digital data acquisition. 
2. BUILDING MODEL ACQUISITION 
A decisive difference between analytical and digital 
building registration is the separation of building 
borderline measurement and height detection . 
The complete process can be sketched as shown in 
figure 2. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996