CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
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This software is able to eliminate outliers and gross errors 
that are present in the laser acquisition. Figure 5 b) shows the 
filtered 3D model. 
Photos have been taken using a Nikon D1X digital camera 
equipped with a 28 mm fixed focus lens. 
Figure 6. The taken image 
A classical survey of the statue has also been carried out, in 
order to check the new procedures, comparing the results. 
4.3 Image calibration 
As the first step, the image calibration was carried out. The 
image size is 1312 pixels in height and 2000 pixels in width, 
the resolution is 300 dpi, corresponding to a pixel size of 
about 12 pm. 
Some high reflecting targets have been placed on the statue, 
allowing the automatic calibration of the image. The 
estimation has been performed using a bundle approach, by 
means of a software package made by our research group. 
In addition, the lens radial distortion coefficients have been 
estimated. 
The obtained results are shown in Tab. 1. 
Image orientation parameters 
Table 1 
camera orientation 
parameters and lens 
distortion 
external 
X 0 
99.982 m 
Y 0 
100.699 m 
Z 0 
103.220 m 
0) 
1.018592 gon 
<P 
3.437747 gon 
K 
-0.19099 gon 
internal 
radial distortions 
-3.776 mm 
K, 
0.000175488 
fio 
-3.677 mm 
K 2 
0.00000076 
c 
28.890 mm 
K 3 
-0.00000003 
Tab 1. Camera orientation parameters and lens distortion 
From the radial distortion coefficients the lens radial 
distortion curve has been obtained, as shown in Fig. 7. 
Ap[m 
4.4 Projection and interpolation 
Once the internal and external image orientations are known, 
the projection of the point cloud onto the image and the 
interpolation of the distance matrix can be carried out. 
The distance matrix can be represented as a grey scale image, 
where the grey levels are proportional to the distances (black 
= shortest distance, white = longest distance), (see Fig. 8). 
4’ 
a) 
b) 
Figure 8. Distance matrix image, a) after the projection 
process - b) after the interpolation process. 
In order to verify if the projection and interpolation processes 
have been carried out in a correct way, it is possible to 
display the RGB original image and the above mentioned 
“distance image” in a same window. It is also possible to 
superpose the two images.