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Coastline Extractor

Hey that's cool. Let's see how it compares to using SHP files of WaterBody data
 
These files are a much less detailed than the SWBD masks. But the hi-res US masks should be OK.

There are also GSHHS files available. Their problem is they are offset about 200 meters to the west! Their documentation even acknowledges this, but they don't want to correct it. And that mislocation isn't always the same.

The SWBD masks also can have problems. They are 'sawtoothed' and sometimes have errors related to cloudcover in the LandSat7 images that were used to make the files. Basically, the masks were drawn on Satellite images, then a raster to vector process made them polygons. For smaller areas we can get better results by drawing vectors in SBuilderX! But for LOD5 areas, this becomes a 'labor of love'.

Sawtoothed shapefiles can be smoothed. There's an interesting website called MapShaper that can do this:

http://mapshaper.com/test/demo.html

Dick
 
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