What map projection and datum are C-CAP data distributed in?
C-CAP data, provided on the Web, are distributed in Universal Transverse Mercator (UTM), North American Datum 1983 (NAD83), meters. The reason for the use of a Mercator-based projection is that raster data are not well represented in Geographic Latitude/Longitude (GLL) projection. GLL is a non-Cartesian coordinate system, meaning that the pixel size will change over space, becoming more extreme as you approach the poles. Since C-CAP images cover approximately 100 miles x 100 miles (more than 1 x 1 degree lat/long), the pixel size would have to change within one project area, causing distortion. This situation causes some serious problems for image processing. For this reason, a Mercator projection is used to maintain a constant pixel size.
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