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Parameter 6, [Pixel]
Exterior orientation 25.20
Interior orientation 5.88
Eccentricity of projection centre 5.63
Non-parallelism of CCD line (2 components) 1.15
Lens distortion 0.60
Affinity 0.45
Non-uniform rotation (periodical deviations) 0.24
Tab. 2: 6, of spatial resection
Translating the resulting 0 of 0.24 pixel into object space, we
receive a lateral point precision between 0.1 (at 2 m distance)
and 0.5 mm (at 10 m distance) when using a 35 mm lens.
According to the length of the CCD line of 10,200 pixel, this
value corresponds with a relative precision 1 : 42,000.
In (Amiri Parian & Griin, 2003) further parameters in addition
to physically defined parameters are used for the compensation
of local systematics. For this purpose the panorama is divided
into pieces, in which a polynomial approach is then used for the
compensation of local remaining systematics. Thus Go = 0.23
pixels was reached, which corresponds to the order of
magnitude shown here.
4, IMPLEMENTATION OF THE MODEL
The mathematical model was implemented into different
photogrammetric applications, with primary focus on a bundle
block adjustment for panoramic images.
4.1 Panoramic bundle adjustment
Using the bundle adjustment, it is possible to determine object
points, orientations and camera parameters simultaneously from
two or more panoramas. An important goal during the
development of the panoramic image bundle block adjustment
was user friendliness, which means among other things that the
computation should get along with as few as possible
approximate values. The implemented solution requires only
three object points to procure approximate values for the
orientation of the panoramas and successively for all object
points. These three object points can be realized for example by
a small reference triangle placed into the object. The adjustment
can be accomplished alternatively with a minimum datum
solution, a certain number of control points or as free network
adjustment. In Tab. 3 the results of two computations, an
adjustment with minimum datum and a free network
adjustment, both with 364 object points and 5 camera positions,
are summarised. As expected, the standard deviations of the
object coordinates are better in the free network adjustment.
This effect can be explained by the datum point distribution.
Fig. 10: Object points of calibration room of AICON 3D
Systems GmbH incl. camera positions
Minimum datum Free network
adjustment
Go [pixel] 0.22
9x [mm] 0.48 0.33
oy [mm] 0.45 0.27
Oz [mm] 1.01 0.15
Tab. 3: Results of panoramic bundle block adjustment of points
in the calibration room
Remaining systematic errors of the camera might result in
object point coordinate errors and not show up in the results of
the bundle adjustment. Therefore the computed object
coordinates were compared with the reference coordinates of
the calibration room. For the stabilization of the block geometry
four well-distributed control points were used. From Tab. 4 it
becomes obvious that the average value of the deviations
amounts to ca. 0.5 mm for all three coordinate directions. It is
not sure, however, whether the small discrepancy between
bundle results and checkpoint deviations can be interpreted as a
limitation of the accuracy potential of the camera, or whether
the deviations are caused by the limited precision of the
reference coordinates.