Fig. 1: Raw image from a Rolleiflex 6006 metric 
with 50 mm focal length 
The presented example is the western facade of the 
Nikolai Church in Jüterbog, south of Berlin, Germany. The 
image is not optimized for the generation of an ortho- 
image, but it is well suited to present the nature of the new 
approach. 
  
Fig. 2: Rectified image using projective 
transformation (scale 1:400 ) 
606 
2. DIGITAL SURFACE MODEL 
Customary software products for the generation of sur- 
face models are designed for digital terrain models. Con- 
sequently they are well suited to handle changes in the 
slopes of surfaces, but not discontinuities in the surface 
itself. 
  
   
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Fig. 3: Plot of a CAD Model of the object 
The new surface modelling approach is based on the 
usage of a CAD model (Fig. 3) of the object to generate a 
Digital Surface Model (DSM). The CAD model may be the 
result of a reduced restitution process only taking such 
edges into account, that have an influence on the shape 
of the surface. In some cases already existing CAD 
models may be used. The model is supposed to consist of 
surface elements, plane or curved, or of volume elements 
(Li 1993). If only a point or wire model is available, 
surfaces have to be generated by connecting the existing 
points and lines. 
In this example a digital photogrammetric measurement 
tool (IMDIS), a meshwise numerical transformation be- 
tween pixel coordinates and metric image coordinates 
making use of the réseau crosses, and bundle adjustment 
(PICTRAN) were used in order to calculate image orien- 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996 
tations 
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