CIP A 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
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Figure 6. First and last image of an image sequence taken with the Sony camcorder (left below) and two views of the VRML
model fully automatically generated from the sequence (top and right).
Figure 6 shows the first and the last image of a sequence taken
with the Sony camcorder and two views of the resulting
VRML model. Of the 1500 images we have taken only seven
to minimize the computational effort. Overall, we obtained 71
7-fold, 60 6-fold, 55 5-fold 24 4-fold, and 4 3-fold points after
robust adjustment and an error of 0.06 pixels. For this camera
only the range of the focal length is known, but not the pixel
size or the metric size of the sensor, i.e., the parameters of the
camera matrix are unknown. Our auto-calibration scheme
resulted into 1.66 for the ratio of principal distance to image
width and 2.38 for the ratio of principal distance to image
height. The precision in image space was 0.25 pixels. It should
be noted that the results have been obtained without user
interaction and with the same set of parameters as for the
above sequence. The two views of the VRML model generated
for the points and the cameras shows that the metric geometry
of the scene has been recovered fairly well.
4.3 Structure computation
Our approach for the computation of 3D structure (Mayer,
2003), i.e., a disparity image in the first place, from an image
pair or triplet is based on the algorithm for cooperative
disparity estimation proposed in Zitnick and Kanade (2000).
The respective image pair is resampled along the epipolar
lines. Matching scores are computed by cross correlation and
absolute differences and written in a 3D array made up of
image width, height, and disparity range. As the computational
effort depends directly on the range of the disparity, we
compute this range by projecting the points reliably
determined for the image triplet onto the epipolar lines.
Figure 7: Disparity map (left) and visualizations based on the disparity map
