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Old 05-19-2010
brak brak is offline
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In process of development I get to compare charts with satellite imagery and it is hit or miss. It is evident that errors enter NOAA ENC data set from time to time due to errors in scanning or setting types of objects from the raster charts.

The most common error I find is location shift. If it happens, it usually will be uniform for a specific chart, and most of the time will be relatively small (under 20 ft), though some charts are shifted by as much as 70ft or more. Of course, since real precision of GPS units is often not much better, it should not be a problem for navigation if navigator does not assume to be exactly where the little "icon on a screen" says he is.

Here is a random screen shot to illustrate the point.
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