[GRASS-user] v.generalize with where clause

Matt Kynx matt at kynx.org
Tue Mar 15 04:42:49 EDT 2011


I'm (slowly ;) getting to grips with GRASS, with the aim of turning
the arctic ice maps from http://ice-glaces.ec.gc.ca/ (.e00) into KML.

The maps contain vectors for the entire Canadian arctic coastline.
Slarty Bartfast would've loved the fiddly bits, but I'd like to smooth
out some of this detail to reduce the size of the maps.

I can do this (radically!) with v.generalize if I first extract just
the land areas.

v.generalize -c --overwrite input=land at arctic output=land_smoothed
type=boundary method=hermite threshold=100000 angle_thresh=20

But if I try and use v.generalize with the same parameters on a map
with ice, sea and land areas, selecting the land areas with a where
clause, no smoothing takes place.

v.generalize -c --overwrite input=a11_centroids at arctic
output=a11_smoothed method=hermite threshold=100000 angle_thresh=20

I only want to smooth boundaries with land - I don't want to touch the
ice-ice or ice-water boundaries. Any idea how I can achieve this?

Also I came across the following "[GRASS-dev] v.generalize no longer
corrupts areas and area attributes":

Is GRASS 7 stable enough for day-to-day use?

Many thanks,


More information about the grass-user mailing list