The sea floor: The sea map base layer is an image of printed nautical charts, contoured by the frame and the coast line. 1:50,000 charts are generally used for the mainland France coast. 1:20,000 charts are also used for estuaries, bays and gulfs and two 1:150,000 charts are used along the Aquitaine coast. 1:50,000 charts will be used for Reunion island, Martinique and Guadeloupe. 1:300,000 charts will be completed by detailed 1:50,000 charts for French Guiana. Assembly tables for maps to be incorporated in the SCAN Littoral® solution can be found in Appendix B.

Land maps: The land map is an image version of the IGN map (raster data from 1: 25,000) contoured at the same coast line, except coastal toponymy, which may appear at sea. The coast line Coast line data (for the highest tide with a tidal coefficient of 120 and in normal weather conditions) were obtained from the HistoLitt® database. These data were prepared jointly by Shom and IGN. Shom larger scale charts were converted to digital format for the required geographic scope (from 1: 5,000 to 1: 50,000 or even 1: 150,000), and updated using the IGN ORTHO® database. This line is now used to match terrestrial data and marine data for our reference materials. On the other hand, this coast line is not defined for the entire length of the French Guyanese coast due to clouds on airborne photographs. Pending the definition of this coast line, the French Guyanese map was compiled using digitally converted terrestrial and marine maps. The technical specifications for the French Guyanese solution are therefore slightly different.