International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 | Interna 
e Apply high density color depth function to generate true orthophoto. This is a function to 
automatically eliminate the occlusion of building, etc. using 
Flowchart of proposal method is shown in figure 5. other overlapping pictures based on DEM and three 
dimensional vector data. 
After implementing the aerial triangulation, we acquired the 
“Photography | edge of streets and external line of two storied and higher 
wih Hoop te building as three dimensional vector data in order to construct 
= is = DSM. We generated the three dimensional surface model based 
at on it. The external lines of buildings that were not facing with 
Bune Rete res | the streets were omitted discretionarily (figure 6, 7). 
  
  
  
  
Judgement | 
Vectorzatbn TanmgetBuilng | 
Depending on EsHeght | 
| Exclhde a One-Stored Houses) | 
* n 
| Vectorzaton | | Vectorzaton | 
| Edge ofRoads | | Edge ofBuillings of 
: Figui 
I 
Generate Sinplifed DEM | | | 
j 
Y Ea. 
Generate r3 
. Botom Ine ofBuillng | | 
Generate ! 
Sin plified DSM TN I3 
  
Y 
Process | 
hdivilual Trueorthophotos | 
  
  
i 
  
Y 
Merge Trueorthophoto with 
Autom atically Drawn Seam Ines | 
  
i 
  
Y 
Export Genarated Seam bss 
Trueorthophotos 
as l6bETEF. 
Figure 5. Flowchart of True orthophoto generation method 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
4. PRACTICAL EXPERIMENT Bi 
We conducted the experiments based on the method discussed 
in the above. The details of experiment are as shown in Table 2. a ta 
lgur 
cover 
Items Description build 
Casel | Case2 | Case3 ou 
Location Vicinity of Shibuya Station Ay 
Weather condition | Taken in November, sunny day Figure7. 3-dimentional surface model around Narrow Street adj 
Photography DMC STO 
Photography scale 1:8,000 Seas, 
Resolution of image | 9.8cm Processing of orthophoto generation is divided into rectification, color 
Overlap of aerial | 607 670 80 occlusion processing and mosaic, but all of them are automatic 
photography processing. 
Side lap of aerial | 30 67 80 A raw image around high buildings is shown in figure 8. 
photography A part of true orthophoto we generated is shown in Figure 9. 
True orthophoto | Image station Ortho Pro Several tiny black areas around wall of buildings can be 
generation software recognized as occlusion. Photographs are overlapping 25times 
in maximum, and those occlusions give an example of difficulty 
Table 2. Experiment work to generate true orthophoto of generation true orthophotos. 
5. RESULTS 
Ortho Pro which is the orthophoto generation module of digital 
photogrammetry system Image station is equipped with the 
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