Kunii, Yoichi 
  
2.2  3DSpatial Data Acquisition 
3D coordinates of an object were calculated using coplanarity condition in this paper. The detail procedures of the 3D 
spatial data acquisition method are as follows: 
+ Extraction of feature points. 
+ Select one line, and one feature point perpendicular to the line on the image. 
- Horizontal length for the line is measured. 
+ Relative ground coordinates for each feature point on the object are calculated by relative orientation using the 
coplanarity condition. 
+ The relative ground coordinates are transformed to absolute ground coordinates using the horizontal length and the 
vertical direction. 
+ The absolute ground coordinates were set as approximate values for the bundle adjustment, and 3D coordinates of 
the each point on the object are calculated. 
Therefore, 3D spatial data is acquired effectively using coplanarity condition and the bundle adjustment. 
2.2.1 Evaluation of Accuracy: In order to evaluate accuracy for the above method, experiment was performed using a 
test model shown in figure 6. The horizontal length from point No.1 to No.2 was given (26cm) and point No.3 was 
selected as the perpendicular point. The squared points are control points for orientation, and another 34 black circle 
points are check points for checking accuracy. Figure 7 shows the stereo image for the test model, and base-depth ratios 
for the stereo image is 0.38. 
  
  
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Figure 6. Test model 
   
(a) Left image (b) Right image 
Figure 7. Stereo image for the test model 
  
462 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
  
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