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After the test phase the computing of orthophoto plans 
with high resolution is done in a stand-alone process. 
The definition of the scale and the pixel resolution (dots 
per inch) is possible for different output media. The 
orthophoto can be combined with line drawings or undergo 
other image processing operations, e.g. edge detection. 
war ian and implementation 
The implementation is based on an open industrial 
image processing system (SunlP/SunVision) for SUN 
Sparc workstations under Unix OS 4.1.2 with 
OPENWINDOWS 3.0. Forthe userinterface ergonomics 
the graphical user interface and the disign principle of 
OPEN LOOK are applied. In SunlP it is possible to 
include own reconfigurable graphical user interfaces 
(GUI), several built-in tools for image handling and own 
image processing algorithms. Also tools for controlling 
and analysing images, subimages and regions of the 
digital orthophoto process are at disposal. In the image 
display the 2D/3D- Graphics-library XGL allows 
displaying, manipulation and integration of geometry 
objects. 
4. FIRST RESULTS 
The used camera was a middle format Rollei 6006 
Réseau (121). For a first test a facade with prevailing 
even planes was chosen. Fig. 4.5 shows the final result 
combined with a superimposed line drawing for geometric 
control of the projections. The three levels of the plane 
hierarchy are represented in Fig. 4.2 to Fig. 4.4. A 
combination of the levels 1 to 3 is demonstrated in Fig. 
4.1. All small planes have been rectified by linear or 
quadratic transformations. Level 1 (Fig. 4.2) shows a 
great main plane, which has been rectified projectively. 
The plane coefficients (17 control points) are determined 
by least squares adjustment. Fig. 4.6 gives the error 
vectors (control points), which symbolize the deviations 
from the adjusted projection plane. The deviations vary: 
mean 1.2 cm, max. 2.9 cm. Using a wide angle lens (c = 
50 mm) this causes a relief transposition Ar of mean 0.9 
mm and max. 2.1 mm in the orthophoto (scale 1 : 25). 
  
  
  
  
  
    
    
Combination of Rectifications 
  
  
Fig. 4.2 Rectification of middie facade (Level 1) 
    
Quadratic 
  
—— Linear 
  
Fig. 4.3 Rectification of middle façade (Level 2) 
  
  
  
  
  
  
  
  
   
Fig. 4.4 Rectification of middle façade (Level 3)