[GRASS-user] r.thin ?

[Markus Neteler]

2010/11/9 Micha Silver <micha at arava.co.il>
>
> On 11/09/2010 06:21 PM, charlie wrote:
>
> Micha and Achim, thank you for the replies.  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 you succeed to separate the boundaries, then run the resulting raster thru r.thin, and finally convert to vector.

In order to remove the JPEG/whatever data compression artifacts, you
can preprocess
with r.seg from GRASS Addons (see Wiki). It does a great job. Then go
on as Micha describes.

Cheers
Markus