Compression of Scanned Aeronautical Chart Data in Support of Naval AircraftDigital Moving Map Systems

摘要

The Map Data Formatting Facility (DMFF), located at the Naval Oceanographic andAtmospheric Research Laboratory (NOARL), is developing a global database of compressed, scanned, aeronautical chart images, called the Compress Aeronautical Chart (CAC). 1 The CAC is stored as a library of Compact Disk-Read Only Memory (CD-ROM) optical disc which are being distributed by the Defense Mapping Agency (DMS). Six different chart scales, ranging from 1:50,000 to 1:2,000,000, will be supported In the CAC. The primary users of this compressed digital chart library are aircraft mission planning systems and digital moving map systems, including those for the AV-88 Harrier, F/A-18 Hornet, V-2 Osprey, and A-12 Avenger 11. The MDFF processes raw scanned chart data (DMS's Arc Digitized Raster Graphics (ADRG) by first transforming the data from DMA's Equal Arc Second Raster Chart (ARC) map projection system into another projection system, known as the Tessellated Spehroid (TS), and then applying two compression algorithms to the data The final compression ratio that is achieved is 48:1. Digital maps, Data bases.