I am following the v.generalize tutorial at http://users.ox.ac.uk/~orie1848/tutorial.html
(we should move that to the wiki before it disappears)
but it doesn't say much about working with areas beyond removing small
ones.
I have a vector area which has a very "steppy" boundary, like from
r.to.vect with a sawtooth pattern at the cell edges. I want to run a
smoothing filter over it to get rid of the jaggy bits.
No matter what method I try my output map is always the same as the input
map, no vertices are created or destroyed.
any ideas how to do this? I know about 'v.clean tool=prune' and Markus
Metz's topology-preserving v.simplify (psst- add it to wiki addons) but
I'd like to learn more about how to use v.generalize.
I am following the v.generalize tutorial at http://users.ox.ac.uk/~orie1848/tutorial.html
(we should move that to the wiki before it disappears)
but it doesn't say much about working with areas beyond removing small
ones.
That page and the images exists in the svn too. How does one go about
adding extra manual pages? Or perhaps we could integrate it into the
manual page itself?
I have a vector area which has a very "steppy" boundary, like from
r.to.vect with a sawtooth pattern at the cell edges. I want to run a
smoothing filter over it to get rid of the jaggy bits.
No matter what method I try my output map is always the same as the input
map, no vertices are created or destroyed.
any ideas how to do this? I know about 'v.clean tool=prune' and Markus
Metz's topology-preserving v.simplify (psst- add it to wiki addons) but
I'd like to learn more about how to use v.generalize.
How large is the cell you exported from? First you have to use a
smoothing operator. When you are done with the smoothing you should use
the douglas method to reduce the number of points.
It produces nice straight lines and with method=douglas threshold=30 you
can get it even better (note that the cell size was 30m) Also note that
the method=snakes I used simply the default values for alpha and beta.
Hi,
Is it possible with grass to replace missing values in a map by surrounding values by a sort of interpolation, knowing that sometimes many missing values are numerous one near another? If yes, how?
Thank you very much
Stéphanie
Hi,
Is it possible with grass to replace missing values in a map by surrounding values by a sort of interpolation, knowing that sometimes many missing values are numerous one near another? If yes, how?
Thank you very much
Stéphanie
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Il giorno mar, 17/02/2009 alle 18.00 +0100, FAROUX STEPHANIE ha scritto:
Hi,
Is it possible with grass to replace missing values in a map by
surrounding values by a sort of interpolation, knowing that sometimes
many missing values are numerous one near another? If yes, how?
Thank you very much
Stéphanie
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a
06125
Perugia (Italy)
Socio fondatore GFOSS "Geospatial Free and Open Source Software" http://www.gfoss.it
e-mail: marchesini@unipg.it
ivan.marchesini@gmail.com
tel: +39(0)755853760
fax (university): +39(0)755853756
fax (home): +39(0)5782830887
jabber: geoivan73@jabber.org
Il giorno mar, 17/02/2009 alle 18.00 +0100, FAROUX STEPHANIE ha scritto:
Hi,
Is it possible with grass to replace missing values in a map by
surrounding values by a sort of interpolation, knowing that sometimes
many missing values are numerous one near another? If yes, how?
Thank you very much
Stéphanie