In spite of the large number of unknowns the numerical
effort for solving the normal equations therefore is relatively
small and practically independent of the number of control
points. With a medium fast computer the computing time will
be within a few seconds for an image of several thousand
lines. (For further advice see /2/). Moreover this amount
for estimating the exterior orientation parameters is small
compared with the ensuing rectification procedure.
Rectification is called the operation, which transfers
every single picture element from its actual (wrong)
position to the real (correct) position.
CONCLUSION
The presented model for geometric rectification of remote
sensing imagery presently is under investigation in re-
gard of achievable accuracy as a function of the number of
control points used. In the second step the developed
computer program shall be applied to practical scanner data.
The necessary terrain height information then will be
derived from digital terrain models (DTM). The DTM as well
as the control points, necessary to meet pregiven accuracy
requirements, can successfully be obtained from photo-
grammetric flights over the scene area.
REFERENCES
/1/ Ebner, H.: A mathematical model for digital rectifi-
cation of remote sensing data. Paper presented at the
XIIIth Congress of the International Society for
Photogrammetry (Comm.III), Helsinki 1976.
/2/ Ebner, H. and Hossler, R.: The use of Gauss Markov
Processes in Digital Rectification of Remote Sensing
Data. Paper to be presented at the ISP-Comm.III -
Symposium, Moskau, July 31 - Aug. 5, 1978.