Hi all.
I'm studying v.generalize; in the past I obtained good results, but now I
keep on getting either 100% or 0% of the original vertices, no matter of
which algorhitm and parameters I select: could this be a bug, or am I doing
something wrong?
Testing on debian testing, grass64-5 from deb unstable, through qgis
interface.
Thanks.
--
http://faunalia.it/pc
On Tue, 03 Nov 2009 11:59:34 +0100, Paolo Cavallini <cavallini@faunalia.it>
wrote:
Hi all.
I'm studying v.generalize; in the past I obtained good results, but now I
keep on getting either 100% or 0% of the original vertices, no matter of
which algorhitm and parameters I select: could this be a bug, or am I
doing
something wrong?
Testing on debian testing, grass64-5 from deb unstable, through qgis
interface.
Thanks.
E.g.:
v.generalize input=south1@butta type=area layer=1 method=douglas_reduction
threshold=1000.0 look_ahead=7 reduction=50 slide=0.5 angle_thresh=3
degree_thresh=0 closeness_thresh=0 betweeness_thresh=0 alpha=5 beta=5
iterations=1 layer=1 output=snake_simpl
Generalization (douglas_reduction)...
Building topology for vector map <snake_simpl>...
Registering primitives...
1000
1488 primitives registered
31776 vertices registered
Building areas...
713 areas built
618 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 1393
Number of primitives: 1488
Number of points: 0
Number of lines: 0
Number of boundaries: 775
Number of centroids: 713
Number of areas: 713
Number of isles: 618
Number of vertices was reduced from 31776 to 31776 [100%]
Finalizado com sucesso
Hello Paolo,
Try v.build.polylines. This was discussed couple of times before. So
you might want to have a look at some older discussions.
Daniel
On Tue, Nov 3, 2009 at 11:07 AM, Paolo Cavallini <cavallini@faunalia.it> wrote:
On Tue, 03 Nov 2009 11:59:34 +0100, Paolo Cavallini <cavallini@faunalia.it>
wrote:Hi all.
I'm studying v.generalize; in the past I obtained good results, but now I
keep on getting either 100% or 0% of the original vertices, no matter of
which algorhitm and parameters I select: could this be a bug, or am Idoing
something wrong?
Testing on debian testing, grass64-5 from deb unstable, through qgis
interface.
Thanks.E.g.:
v.generalize input=south1@butta type=area layer=1 method=douglas_reduction
threshold=1000.0 look_ahead=7 reduction=50 slide=0.5 angle_thresh=3
degree_thresh=0 closeness_thresh=0 betweeness_thresh=0 alpha=5 beta=5
iterations=1 layer=1 output=snake_simpl
Generalization (douglas_reduction)...
Building topology for vector map <snake_simpl>...
Registering primitives...
1000
1488 primitives registered
31776 vertices registered
Building areas...
713 areas built
618 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 1393
Number of primitives: 1488
Number of points: 0
Number of lines: 0
Number of boundaries: 775
Number of centroids: 713
Number of areas: 713
Number of isles: 618
Number of vertices was reduced from 31776 to 31776 [100%]Finalizado com sucesso
--
http://faunalia.it/pc
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Hi,
2009/11/3 Daniel Bundala <bundala@gmail.com>:
Try v.build.polylines. This was discussed couple of times before. So
you might want to have a look at some older discussions.
probably it would be good to document it or at least to mention it in
the manual/tutorial of v.generalize (if it's not).
Martin
--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa
Hi Daniel.
Thanks for your reply. I'm trying to generalize (and smooth) polygons, not
lines, so your suggestion do not apply.
Any other hint?
All the best.
On Tue, 3 Nov 2009 18:20:39 +0000, Daniel Bundala <bundala@gmail.com>
wrote:
Try v.build.polylines. This was discussed couple of times before. So
you might want to have a look at some older discussions.
Paolo Cavallini wrote:
Hi Daniel.
Thanks for your reply. I'm trying to generalize (and smooth) polygons, not
lines, so your suggestion do not apply.
No, Daniel's suggestions do apply because you want to generalize boundaries. If an area is defined by many short boundaries, there is nothing to smooth because each boundary is processed separately and you need to build polylines first in order to get nice results. See previous posts on this topic.
Also type=boundary instead of type=area would help.
Markus M
Any other hint?
All the best.On Tue, 3 Nov 2009 18:20:39 +0000, Daniel Bundala <bundala@gmail.com>
wrote:Try v.build.polylines. This was discussed couple of times before. So
you might want to have a look at some older discussions.
Markus Metz ha scritto:
Also type=boundary instead of type=area would help.
That was it.
Now fixed on QGIS trunk.
Thanks a lot.
--
Paolo Cavallini: http://www.faunalia.it/pc