Hamish, you are correct, it is Hempstead Bay, I have downloaded the most current vector map from NYS. The raster map I am looking to convert is not a recent map, but from 1929.
Thanks for the tip on the S-57 driver, it is not something that I was aware of. --- On Wed, 11/10/10, Hamish <[email protected]> wrote: From: Hamish <[email protected]> Subject: Re: [GRASS-user] r.thin ? To: "charlie" <[email protected]> Cc: "GRASS user list" <[email protected]> Date: Wednesday, November 10, 2010, 6:02 AM charlie wrote: > In response to your questions, I am trying to convert a raster > map (a scanned & georeferenced map with only XY data) > with a shoreline and some wetland islands into a vector map > so I can compare gains/losses over time. > > A preview of the map is here: > http://historicalcharts.noaa.gov/tiled_jpgs_done/zoomifyURLDrivenWebPage.htm?zoomifyImagePath=579-12-1929 if I am getting that right, the area is Hempsted Bay? if so fyi NY DEC (DECRP/NYS GIS Clearinghouse) maintains vectors of the wetland areas already, e.g. these are loaded into OpenStreetMap, metadata in the data layer there. http://www.openstreetmap.org/?lat=40.59313&lon=-73.60279&zoom=15&layers=M hmmm, but maybe only protected/listed/named areas are covered? also the ENC version of the nautical chart can be imported with v.in.ogr's S-57 driver, and you can extract the features that way (but s57 is a bit ugly to work with in this context) Hamish
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