[GRASS-user] r.thin ?

[Hamish]

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