Case Study: NGA (National Geospatial-Intelligence Agency)
The seabed changes continuously, especially close to land, due to storms, changes in ocean currents and man-made disasters and activity.
Digital Nautical Chart (DNC) is a relational, vector-based digital data base which replaces approximately 5,000 paper nautical charts. When DNC is integrated with ship's radar, GPU and other applications, it dramatically reduces the 80% of marine mishaps caused by human error. It provides the mariner with advanced electronic warning of unforeseen dangers with fewer shipboard personal.1 "DNCÂ® and ECDIS-N are the greatest advancement in safe navigation since the introduction of radar."2
DNC was created and maintained by NGA (National Geospatial-Intelligence Agency) for use by the US Navy and US Coast Guard. Planned future use by commercial shipping will have major positive environment impact by practically eliminating oil tanker and other chemical spills. DNC is compiled from US, foreign and NGA charts, notices to mariners, imagery, hydrographic surveys and other miscellaneous sources. DNC is continually updated with changes to the source materials. These changes come out in a new edition DNC. Currently, approximately 6,000 changes are made each month.
Baseline DNC CD's are stored on the end-user's hard drive. Then patches may be applied by a CD or NGA Gateway which automatically updates the DNC data. The patches are cumulative so the most current data is always available.
The Baseline DNC is multi gigabyte sized. The pipe gets very narrow at the level of the individual ship so it is necessary to drastically reduce the update size. Since the inception of the program, more than 750,000 different patches have been flawlessly created and used by the ships.