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Old 10-25-2013
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Re: NOAA To Stop Printing Nautical Charts

Raster (RNC)charts are just photocopies of the paper charts, calibrated to work with plotters. Electronic navigation (ENC) charts are vector based which means they are point-based, mapped by showing the locations of known individual points, depths, and objects. That's why they don't have elevation lines for the land masses like the rasters. I don't know how they estimate shoreline location but I'd guess they use the lines from the original rasters. Maybe someone else can fill in on the exact procedure they use to come up with an ENC.
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