Figure 2: The Internet data set (A, B, C and D) used for the 3-D reconstruction.
Changed details between the images (E/F and G/H).
Figure 3: The three metric images acquired in Bamiyan in 1970 by Prof. Kostka (A, B, C)
and the acquisition geometry (D).
The distribution of the control points on the statue, measured on the contour plot of Prof. Kostka (E).
The main problems of these images are their differences in size
and scale, the unknown pixel size and camera constant and
most of all the different times of acquisition; therefore some
parts visible in one image are missing in others (Figure 2 - E, F,
G, H). Also the illumination conditions are very different and
this can create problems with automatic matching procedure.
The metric images were acquired in August 1970 with a TAF
camera [Finsterwalder and Hofmann, 1968]. The TAF
(Terrestrische Ausrüstung Finsterwalder) is a photo-theodolit
camera (Figure 4) that acquires photos on 13x18 cm glass
plates. Two fiducials marks are present on the longer sides of
the photos while a moving pointer signs the horizon with an
index that moves vertically. The original photos were scanned
by Vexcel Imaging Inc with the ULTRA SCAN 5000 at a
resolution of 10 micron. The resulting digitized images resulted
in 16930 x 12700 pixels each (Figure 3 - A, B, C). A contour
plot of the big statue, done by Prof. Kostka [Kostka, 1974], is
also available (20 cm isolines, scale 1:100). From this plot
some control points could be measured and used for the
orientation process.
2.1 Interior orientation
2.1.1 Internet images
For every image, the pixel size and a focal length are assumed,
as well as the principal point, fixed in the middle of the images.
With this last assumption, we consider the size of the found
images as the original dimension of the photo, while they could
be just a part of an originally larger image. The assumed pixel
sizes are between 0.03 mm and 0.05 mm.
2.1.2 Metric images
In all TAF images the principal point is defined as the
intersection of the straight line joining the two fiducials marks
on the upper and lower side of the image and the horizontal line
passing through the horizontal index defined on the right side of
the image (Figure 4). The focal length of the camera is 160.29
mm [Kostka, 1974].
-
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upper fiducial mark
moving
a a < vertical
index
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i |
I |
lower fiducial mark
Figure 4: The TAF camera (left) and
the interior orientation of the images (right)
2.2 Exterior orientation
2.2.1 Internet images
As no other information is available, we first performed an
interactive determination of the camera positions, varying also
the value of the focal length and using some control points
measured on the contour plot of Prof. Kostka. Then we refined
these approximations with a single photo spatial resection
solution.
2.2.2 Metric images
In [Kostka, 1974] the acquisition procedure is described (Figure
3-D). The images were acquired in normal case, with a double
baseline and a distance of ca 130-150 m from the statue. Using
this information and some control points measured on the
contour plot we achieved the first approximations of the
exterior orientation.
2.3 Bundle adjustments
The final orientation of both data sets was achieved using
bundle adjustments and the control points measured on the
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