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Title
Close-range imaging, long-range vision

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4. ORIENTATION OF PANORAMAS
4.1 Definitions
The orientation of panoramas is decsribed in analogy to
standard methods of close-range photogrammetry based on a
cartesian coordinate system. Fig. 10 illustrates the orientation
parameters of a single panorama. The essential parameters are
defined by the position (X,,Y,,Z,) of the cylinder projection
centre, and the initial direction q of the panorama image. The
tilt angles & and « describe a possible deviation of the tripod
rotation axis from the vertical direction. Using bubbles these
angles should be small.
In order to get the orientation parameters of several panoramas
simultaneously, tie points between these panoramas are
required. The orientation accuracy mainly depends on the use
of natural or signalised points. As an example, Fig. 11 shows
measured signalised tie points.
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Fig. 11: Measured tie points in a panorama
Tie points represent angular directions within a panorama. For
the adjustment process the observation equations (6) are set up
according to Lisowski & Wiedemann (1999). Due to the pre-
adjustment of the camera/tripod unit it is not necessary to
consider the excentricity between rotation axis and perspective
centre.
Additional required information are, on the one hand, an
absoulte dimension of the coordinate system. This can be
derived by one or more measured object distances between tie
points. On the other hand, the datum of the coordinate system
has to be defined. This problem is solved by fixing the
orientation parameters of one of the panoramas, e.g. by setting
all values to zero.
In this way a "model coordinate system" with real dimensions
is achieved. If this system shall be transformed into a global
coordinate system (e.g. building coordinate system) a 3-D
transformation based on control points can be applied.
Alternatively, additional constraint equations can be introduced
into the adjustment process.
4.2 Orientation process
The non-linear orientation process requires appropriate initial
values of all unknowns. Usually an iterative calculation of
approximate values is performed for photogrammetric bundles,
such as a combination of relative orientations and resections. In
our case there is no calculation of approximate values but, we
assume that all panoramas cover the same room. Thus, all
panoramas are assigned with equal coordinates of the cylinder
origin and equal tilt angles (70) except the inital direction q.
The first panorama has q-0, the subsequent panoramas are
oriented with respect to the first one, whereby an approximate
orientation angle of + 45° is sufficient.
The initial values of unknown object coordinates are calculated
from the first panorama with constant distance r, that equals,
for simplicity, the average point distance in object space as
shown in Fig. 12. The light grayed area represents the imaged
room.


Fig. 12: Grafical sketch of the start situation for initial
values of orientation process


Fig. 13: Grafical sketch of the iterative adjustment process





Fig. 14: 3-D view of the orientation result
Fig. 13 illustrates the progress of the orientation process (final
result in Fig. 14). It is clearly visible that the final orientation
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