Evaluation of Nautical Chart Adequacy in the Coastal Area around Incheon Bay using Satellite Imagery with AIS Data

Automated Identification of Discrepancies between Nautical Charts and Survey Soundings

“…The International Hydrographic Organization (IHO) has created a standard vector format, named S-57, for official ENCs (that is, produced by a government hydrographic office) that contain a set of data layers for a range of hydrographic applications. However, an IHO S-57 ENC is mainly used, in combination with positional information from navigation sensors and radar data, by an Electronic Chart Display and Information System (ECDIS) to provide a graphical representation of a marine area, including bathymetry and topography, and to assist the mariner in route planning and monitoring by providing natural features, man-made structures, coastlines, and any other information related to marine navigation [6,32]. To meet high standards of reliability and performance, an extensive body of rules defines an ECDIS with the result that, under SOLAS Chapter V regulations, an ECDIS loaded with official ENCs is currently the only alternative for the navigator to the adequate and up-to-date paper charts [33].…”

“…Furthermore, on the other side, reasons of economic effectiveness cause merchant vessels to venture into approaches with less under keel clearance than before [3]. In addition, various natural events (e.g., hurricanes, high sedimentation rates) and human activities (e.g., dredging) may modify the condition of the premises and suddenly make parts or, in extreme cases, the entirety of a chart obsolete [5,6]. Thus, not only the quality of a nautical chart depends on the surveys upon which it is derived but surveying for avoiding chart obsolescence represents a never-ending task.…”

“…This translates to the fact that decades may past until a new hydrographic survey can be conducted in a given area. In such an optic, it is becoming more and more obvious that evaluating the adequacy of the chart portfolio requires not only using newly collected bathymetric sonar bathymetry (BSB) but any possible source of geospatial information like automatic-identification system (AIS) data or alternative surveying means such as synthetic aperture radar (SAR) shoreline extraction, satellite-derived bathymetry (SDB), and airborne-lidar bathymetry (ALB) [6,[14][15][16][17][18][19][20]. However, given the physically-limited penetration in water of SAR, SDB, and ALB as well as the circular limitation in retrieving information from AIS data (i.e., vessels tend to avoid uncharted areas), BSB surveys-despite their high cost and logistic challenges-not only provide both highly accurate and dense measurements of the seafloor morphology, but also represent the only practical source of hydrographic information for large parts of the ocean [15].…”

Automated Identification of Discrepancies between Nautical Charts and Survey Soundings

“…And, on the other side, reasons of economic effectiveness cause merchant vessels to venture into approaches with less under keel clearance than before [3]. In addition, various natural events (e.g., hurricanes, high sedimentation rates) and human activities (e.g., dredging) may modify the condition of the premises and may suddenly make obsolete parts or, in extreme cases, the entirety of a chart [5,6]. Thus, not only the quality of a nautical chart depends on the surveys upon which is derived but surveying for the purpose of keeping nautical charts up to date represents a never-ending task.…”

“…Those offices must balance such a pressing need with the limited available resources and survey priorities that translate to the fact that decades may past until a new hydrographic survey can be conducted in a given area. In such an optic, it is becoming more and more obvious the requirement to evaluate the adequacy of the chart portfolio not only using newly collected bathymetric sonar bathymetry (BSB) but any possible source of geospatial information like automatic-identification system (AIS) data or alternative surveying means like synthetic aperture radar (SAR) shoreline extraction, satellite derived bathymetry (SDB) and airborne-lidar bathymetry (ALB) [6,[14][15][16][17][18][19][20]. However, given the physically-limited penetration in water of SAR, SDB and ALB or the circular limitation in retrieving information from AIS data (i.e., vessels tend to avoid uncharted areas), BSB surveys -despite their high cost and logistic challenges -not only provide both highly accurate and dense measurements of the seafloor morphology, but also represent the only practical source of hydrographic information for large parts of the ocean [15].…”