DEPTH PROCESSING

The swath-data processing underwent the following guidelines:

1. division of the surveyed area into main geographical sectors (projects), e.g. the Sardinia Channel, the Sardinia Margin, The Central Thyrrhenian, the Northern Thyrrhenian and the SouthEast Margin, including the data acquired during the 1996 survey;

2. creation of blocks (NEPTUNE) within the above geographical sectors, with an average number of points of 500000;

3. line positioning processing (smoothing with cutoff frequency 0.07 and filter length 20), with NEPTUNE's POSPROC Module;

4. depth processing with the appropriate sound velocity profiles (generated upon the XBT and statistical data) and additional local processing if necessary, with NEPTUNE's DEPTHCORR Module;

5. block processing with Statistical or hand filtering, with NEPTUNE's BINSTAT Module (cell size ranging from 100 to 200 m, according to the crosstrack resolution of the data, noise 3%, local rules to get rid of macroscopic depth errors); a lot of effort was applied in order to keep as much of valid data as possible. This was not always sufficient to eliminate some of the errors that were present on the ovelapping swaths on deepest areas.

6. export of the block data in NEPTUNE binary xyz format (geographical);