o 
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.