Fig.15: Orthophoto processing 
It has to be mentioned, that this processing is not a strong orthophoto rectification. But 
as pitch has no influence on horizontal distance and yaw motion is in the order of the hori- 
zontal image point resolution this form of rectification is good enough for interpreta- 
tion and planning activities. A further step is the consideration of sensor positioning for 
absolute rectification. 
6. Conclusion 
In combination with the hardware equipment an interferometric recording and processing 
Sonar-System has been developed. which is able to produce topographic maps from the 
sea-floor together with geometrical corrected images. This rises the possibilities for better 
interpretation of sea bottom features. Controlling activities in prospectorial areas as 
well as change detection in tidal areas can be done with less operational expense because 
of area covering data recording. The digital data evaluation gives the possibility for auto- 
matic processing. The software is part of the extensive modular system for digital geo- 
metric and densitometric image processing called MOBI, which allows special evaluations 
for better feature seperation. The hardware system is developed for shallow water areas, 
but it seems possible to use a system like this for deep sea activities. 
References 
BELDERSON, R.: Sonographs of the sea floor. A picture atlas. Elsevier Publising Co. New 
York, 1972 
CASTLEMAN, K.: Digital Image Processing. Prentice Hall, 1974 
CHESTERMAN, W.D., St. QUINTON, J.M.P., CHAN, Y., MATTEWS, H.R.: Acoustic survey 
of the sea floor near Hong Kong. International Hydrographic Review, 1976 
CLERICI, E.: Über die Anwendbarkeit von Side Scan Sonar zur Erstellung von topographi- 
schen Karten des Meeresbodens. Wissenxchaftliche Arbeiten der Fachrichtung Ver- 
messungswesen der Universität Hannover Nr.71, Dissertation 1977