CADRG Compressed (ARC Digitized Raster Graphics, .cadrg)

CADRG (Compressed ARC Digitized Raster Graphics) is a general-purpose product, comprising computer-readable digital map and chart images. CADRG data is derived directly from ADRG and other digital sources through downsampling, filtering, compression, and reformatting to the Raster Product Format (RPF) Standard.

The ARC system divides the surfaces of the earth ellipsoid into 18 latitudinal bands called zones. The CADRG database is composed of rectangular grids of frames of pixels for each zone. Each frame is represented by a discrete file, and the data files are arranged in a hierarchical directory/subdirectory structure. The location and name of each file are recorded in a CADRG table of contents (TOC) file in the root directory.