Anselm Schmieder 
  
5.2 Quality of Contour Lines 
Figure 4 shows the results for the different methods. A visual comparison of the derived contour lines with ancillary 
contour lines issued by the Bavarian topography survey office showed, that the accuracy is in the range of + — 1 meter. 
Due to the fact, that the latter contour lines come from a survey of the year 1911, we can assume that there was some 
topographic erosion since these times. So, the comparison of our data, recorded in 1997, with this old data is somehow 
problematic because of the 86 years time lag. 
  
  
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Figure 4: Countour Line Approximation Methods: (a) No approximation, (b) take each 10th point, (c) Pavlidis and (d) 
Douglas-Peuker. 
5.3 Cartographic Products 
Figure 5 the comparison to the ancillary data for the contour lines smoothed using the Douglas-Peuker algorithm, which 
was visually identified to produce the best results. Additionlly, manual classification derived from X-Band radar backscat- 
  
276 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part Bl. Amsterdam 2000. 
  
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