The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
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3. ACCURACY TEST 
For the calibration of the K750i, eighteen images from three 
locations (each of which has three stations, i.e., down, middle 
and up) were taken in a convergent geometry mode (Figure 4a). 
Nine images were taken in normal mode (image no. 1-9) and 
each three of the rest nine images are -90° (image no. 10-12), 
+90° (image no. 13-15) and 180° (image no. 16-18) rotated, 
respectively. 
Scale bar 
Figure 3. The 3D testfield and the Axyz system. 
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(a) 
(b) 
Figure 4. (a) Image acquisition geometry for the calibration of 
K750i, and (b) for N93, W100 and F828. Black circles stand for 
the image stations. 
For the calibration of the N93, W100 and F828 cameras an 
image acquisition geometry with thirteen images (Figure 4b) 
was used. Images no. 1-9 are in normal mode and no. 10-13 are 
the rotated ones. However, different rotated image versions 
were used. For the camera N93 the images no. 10 and 11 
were -90° and no. 12 and 13 were +90° rotated, for W100 no. 
10-13 were all +90° rotated, and for F828 no. 11 and 13 
were -90° and no. 10 and 12 were +90° rotated. For N93, W100 
and F828 the focal length was set to the smallest possible value 
by zooming. 
(e) (f) (g) (h) 
Figure 5. Image quality of the cameras, (a), (b), (c) and (d) are 
cropped images at station 4 from K750i, N93, W100 and F828, 
respectively. The signalized point approximately locates at the 
centre of the image. Image scales are 1/863, 1/829, 1/460 and 
1/513 for (a), (b), (c) and (d), respectively, (e), (f), (g) and (h) 
are cropped images at station 1 from K750i, N93, W100 and 
F828, respectively. The signalized point approximately locates 
at the upper left part of the full image. Image scales are 1/977, 
1/961, 1/550 and 1/583 for (e), (f), (g) and (h), respectively. 
The image measurements were performed with the Least 
Squares template matching (Gruen, 1985) using the in-house 
developed software BAAP. Another in-house developed 
software SGAP (Beyer, 1992) was used for the bundle block 
adjustment with self-calibration. 
The imaging quality differs among the cameras. In Figure 5a, 
5b and 5c, low-level image enhancement effects are strongly 
visible at the edges of the points. The F828 has the best overall 
image quality considering all images from all stations. On N93 
images (Figure 5b and 5f) strong JPEG artifacts are visible 
(Figure 6). The K750i, N93 and W100 have only the JPEG 
output option. Their image measurements were carried out on 
their original JPEG images. For the F828, TIFF output images 
were used for the image measurements. 
Figure 6. 3X zoom-in of the upper left part of Figure 5f. JPEG 
artifacts are visible. 
3,1 Accuracy test of K750i 
The 18 images version gives a sigmaO value of about half a 
pixel (version 10 in Table 2) and highly systematic residual 
patterns in some images (Figure 7a and 7b), even after self 
calibrating bundle adjustment with block-invariant additional 
parameters.