Computer enhanced GLORIA sidescan sonar images of the surface of the Mississippi Fan

Abstract

In 1985 the United States Geological Survey and the Institute of Oceanographic Sciences (UK) mapped the seafloor of the Gulf of Mexico, within the US Exclusive Economic Zone, using GLORIA sidescan sonar (Fig. 43.1). The GLORIA system operates at a frequency of 6.5 kHz and the beam has a wavelength of c. 23 cm. The digitally processed mosaic is published as black and white images at a scale of 1:500000 (EEZ-Scan 85 Scientific Staff 1987). The interpretation of the images and profiles from the Mississippi Fan is discussed in Twichell et al. (1991). The GLORIA data are available on a CD-ROM optical disc. Further enhancement has been carried out for that part of the data that covers the Mississippi Fan, the Florida Escarpment and neighbouring regions (Sinding-Larsen and Wen 1990). This enhancement involved filtering, colour coding, feature extraction and classifications; the resulting image is shown as Fig. 43.2.