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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part Bl. Istanbul 2004 
  
  
Figure 8. The left image is the DTM from automatic process and the right one is from digital maps. 
The green line shows the region for accuracy evaluation 
  
Figure 9. The difference image between automatic DTM and original DTM. 
The red lines show some of the gross error regions. 
3. ERDAS IMAGINE 
The ERDAS IMAGINE is an image processing package for 
processing spatial data. It has many different kinds of tools 
which enable the user to process, manipulate and analyze the 
data in both raster and vector formats. This software consists of 
different modules. The module which handles the 
orthorectification and automatic DTM extraction is 
OrthobasePro. It is capable for different kinds of sensors like 
Aerial imagery, close range imagery and optical satellite 
imagery (IRS, SPOT, IKONOS and QuickBird). This research 
is for evaluating the capability of the software in handling 
SPOT 5 stereo imagery for automatic DTM generation. 
In this study both ERDAS IMAGINE v8.6 and v8.7 are 
evaluated. Section 3.1 describes the process and the result for 
v8.6 and section 3.2 describes the process and the result for 
v8.7.