[GRASS-user] Smoothing algorithim to remove small spikes

spiderplant0 spiderplant0 at gmail.com
Sat Oct 8 14:14:08 EDT 2011

Hi, I have a vector map that has some narrow features (boat jettys etc) that
I wish to smooth out. Can anyone suggest a method of achieving this please?
I have tried several of the algorithims in v.generalise without success. 

One of the problems I am experiencing is that small details seem to be
treated similarly to large scale detail. 

See links to example using snakes method.

Map prior to filtering...

Map after filtering...

Composite map....

At the bottom-left of the map I have small spikes that I want smoothed over.
They have been smoothed out reasonably well but the large spike has been
converted into a short fat spike. I.e. it has been reduced in size by around
the same percentage as the small ones. Also at the top-right of the map, a
huge area of land has been chopped off. 

Its as if the smoothing algorithm didnt take account of scale but just
consider a number of vertices each side of the point and apply the filter
without considering how far apart in metres the points are.

What I'm looking for is a way to smooth out the small detail especially
small spikes, but not chop out big areas of land at larger scales.

View this message in context: http://osgeo-org.1803224.n2.nabble.com/Smoothing-algorithim-to-remove-small-spikes-tp6873002p6873002.html
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