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always be applied in terrestrial photogrammetry as is usually
the case in aerial photogrammetry.
On the other hand the calibration work itself is no real pro-
ductive job! So, it should be very simple, it should be possible
to repeat it very quickly at any time (preferably not at night
time as is the case with stellar-calibration). To meet these
circumstances properly terrestrial testfields are suited best
to evaluate the wanted set of calibration data.
2. THE CAMERA CALIBRATION CONCEPT
However, the use of terrestrial testfields for calibration is
not without problems. A very high precision for its geodetic
determination is necessary and - more difficult - its points
should be stable over a longer period of time to use the field
several times. Since both requirements can only be realized at
high expence the following calibration procedure is now pro-
posed:
1. The testfield should be established in its size as small as
possible.
So, it can be remeasured by geodetic means very quickly.
2. As a consequence the camera format will not be filled by one
image of the testfield. However, the format can be complete-
ly filled up with imaged terrestrial points by taking several
photos: partly with the same, partly with diverging camera
axis, but all taken from only one station belonging to the
testfield.
5. Since all photos are taken from the same station there are
tie conditions between image parameters to strengthen the
mathematical model.
4, Images taken under the same orientation angles should serve
in two respeots:
First, they should help to reduce the necessary number of
terrestrial points. :
And secondly, they should improve the stochastical model.