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Fig.B. System for Data Preprocessing and Recording
4. The Data Processing Software System
The hardware system presented before is a prototype for interferometric sonar imaging
with the aim of processing these data for the determination of three-dimensional space-
coordinates from the sea-bottom. The system works up to water depths from about 80 m
and ranges up to 150 m. Figure 8 shows a part of a track recorded near Hoek van Holland
in cooperation with the North-Sea Directorate of Rijkswaterstaat in the Netherlands.
From the beginning it was the idea to process the obtained data off-line with digital
methods. This is done by special image processing software. which is part of an exten-
sive modular software system at Hannover University called MOBI (German: Modulares
Off-line Bildverarbeitungssystem), that is made for the evaluation of remote sensing
data (Kolouch et al., 1981). The videotape recorded sonar data are first of all digitized
by using an A/D-converter and a double buffer interface at a DEC VAX 11/750 computer
system. The images are stored on CCT (computer compatible tape) for further evalua-
tion. Prerequisite for this is the development of a geometrical and mathematical model.
