[GRASSLIST:3706] coastline/breakline question using r.surf.contour

[Roy Sanderson]

Dear GrassUsers

I'm creating a DEM from what is originally a vector map of contours
(imported from a dxf file).  The contours have been 'rasterised' using
v.to.rast, and then running r.surf.contour on this to create the DEM.  The
resulting DEM looks fine, except around the coastline and estuaries, where
the interpolation has continued beyond the shore.  I have a vector map of
the coastline, as a line rather than a polygon since it goes to the edge of
the map.  Is there a simple way of forcing r.surf.contour to ignore these
sea/estuary areas?  One solution might be to use the coastline vector to
create a 'sea v land' raster, and r.mapcalc this onto the DEM.  However,
how to convert the coastline vector to a polygon is not obvious, since it
is incomplete on the seaward side of the map (hence v.line2area ignores the
coastline vector).

I'm running Grass5.0pre4

Any suggestions gratefully received.
Roy

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Roy Sanderson
Centre for Life Sciences Modelling
Porter Building
University of Newcastle
Newcastle upon Tyne
NE1 7RU
United Kingdom

Tel: +44 191 222 7789
Fax: +44 191 222 6563
r.a.sanderson at newcastle.ac.uk
http://www.ncl.ac.uk/clsm

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