Kakiuchi, Tsutomu 
  
3 CAMERA CALIBRATION USING VIDEO THEODOLITE 
For camera calibration, control points should be generated and its image 
coordinates also should be acquired. Camera calibration procedures are as 
follows: When the telescope is pointing to Py point under the condition 
that the distance is D from the center of the video theodolite to R, 
horizontal angle H, and vertical angle V;, the image point to Po is taken as 
po on the right and left image respectively. Next, when the video 
theodolite is rotated H; angle, the image point to Po is taken as p; on the 
right and left image, and the object position to image point p; becomes Pj. 
Similarly, when the video theodolite is rotated V; angle, the image point 
to Py is taken as p», the object to p? becomes P». Repeating this operation, : sine 
control points are taken on the stereo image and are produced in the space Figure 5. Camera calibration 
respectively based on Figure 5. 
Ground coordinates for these control points are calculated following equation. 
  
X; = DcosV, sin(H, H,) 
1 
Y;- Dos V;sinV, sinV;cosV, cos(H; H, X (1) 
Z; = Disinv, sinV, + cosV; cos V, cos(H, H,) 
Camera calibration for the right and left image was performed using 9 control points, which were produced in the above 
procedure. 
4 PRE EXPERIMENT 
4.1 Experiment Method 
In order to estimate the accuracy of 3D measurement of the stereo vision system and the relationship between the 
rotation parameters ( "  ) and the reading angles (zenith, horizontal) of the video theodolite, the following pre- 
experiments were performed using the test field (Figure 6). 
Figure 7 shows the three test models (Z=0mm, 20mm, 50mm) were used in this paper. The black white rectangular 
target is a control point corresponds the above Py, and other 38 black circle points are check points for checking 3D 
accuracy 
  
  
  
  
  
  
  
  
  
® 00 00 
4cm - Control Point (Po) 
€ es. 
dem d «€ e Z = 0mm, 20mm, 50mm 
4cm 
i ® 00 00 
cm 
f ® 00 00 
cm 
® 00 0600 
"HFeejeejee 
4cm 7cm 4cm 7cm 4cm 
Figure 6. Test site Figure 7. Test model 
The following image A1 (Figure 8) was taken from 2.4980m as the original 
orientation image. The left-hand number superimposed in the upper left corner 
shows the horizontal angle Ho=0 00). The number just to the right is the 
zenith (Vo=0 00, V=90 -Zenith angle) and the distance (D=2.4980m). 
Figure 9 shows the right and left image for camera calibration which was 
interpolated by above concept. 
Camera calibration for the right and left image was performed by the same 
procedure noted above using one control point on the test model. 
For the unknown parameters, exterior orientation parameters( "o, 0, 0 
(rotation parameters), Xo, Yo, Zo (camera positions) and interior orientation 
parameters (f, xo, yo (principal points), a;, a? (scale factor), p ;(lens distortion)}. 
    
Figure 8. Orientation image 
  
416 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000.