Histogram | Histogram 2 Histogram 3 
        
  
   
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
   
  
  
  
Histogram 4 Histogram 5 Histogram 6 
Figure 11 Histogram of digital Images 
5.2 DEM Creation and Editing 
LOD OCT TPA OT 
  
Figure 12 DEM (GRID Model) 
Digital Elevation Model (DEM) is 3D data format analyzing 
and expressing surfaces of an object by 3D modeling, which is 
the major element for geographic data processing. For creating 
and editing DEM, MTA (MGE Terrain Modular) was used and 
so TIN model and Grid model were generated. Grid structure, 
advanced 2D matrix, can easily manipulate elevation matrices. 
Then, this study used Grid model to create DEM. Figure 12 
illustrates Grid model layout generated and edited on MTA to 
create orthographic images. 
(XY, Z^ 
   
   
   
   
   
Original f 
Image (x.y) 
Image 
iz) 
DEM 
Grey V alue 
  
Ortho Image 
  
  
Figure 13 Digital Ortho Rectification 
5.3 Creation of Orthographic Images using DEM 
ER-mapper 6.1 was used for creating orthographic images 
and orthographic rectification approach was applied using 
reference points. Orthographic image creation using digital 
displacement correction approach conducts correction with 
     
    
  
  
ai 
Figure 14 Ortho Image (ER-mapper6.1) 
respect to exterior orientation factors, interior orientation 
factors, focal distances and collinearity conditions during the 
process to move DN values of original images to image 
coordinates of DEM. It adopts the principle as shown in Figure 
13. After substituting 3D ground coordinates of each pixel of 
DEM to collinearity condition formula, images were converted 
to original image coordinates. Brightness was determined by 
interpolation on pixels around corresponding original image 
coordinates and saved on each pixel position of DEM. 
Figure 14 describes orthographic images acquired for digital 
images of an object. At this point, bilinear interpolation was 
applied to interpolation of images and regenerated to ll’. 6 
orthographic projection images were tessellated on Intergraph 
Image Analyst. Acquired mosaic images were edited using 
Photoshop5.0 for correction on mosaic seam. Figure 15 shows 
orthographic image outputs before editing related to each 
digital data and Figure 16 presents combined images of 
orthographic images and vectors corrected by Photoshop. 
Contour and orthographic images of a target showed proper 
matching through correction of distortion. 
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