[GRASS-dev] [GRASS-user] generalize polygons including holes

[taking this over to grass-dev]

On 05/02/15 18:23, Markus Metz wrote:

On Thu, Feb 5, 2015 at 4:56 PM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

On 05/02/15 14:49, Markus Metz wrote:

On Thu, Feb 5, 2015 at 11:50 AM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

On 05/02/15 10:06, Markus Metz wrote:

v.generalize does not distinguish between outer and inner rings, it
simply goes through all boundaries and generalizes each one.

And this has always been the case or this is specific to GRASS7 ?

This has always been the case.

Then why doesn't there seem to be any generalization happening for the hole
boundaries of the test dataset with grass64release ?

With the test dataset you provided, GRASS 6.4 does generalize the hole
boundaries. I do not have the problem vector of Robert, so I can not
say if the hole boundaries in that vector are generalized or not.

With a make distleaned, svn updated and recompiled grass64relase, using the test data and the commands

v.generalize test method=douglas thresh=100 out=test_gen_100 --o
v.generalize test method=douglas thresh=500 out=test_gen_500 --o

I get the attached result (red = 100, orange=500). I don't see any generalization in the holes as I do with the same commands in GRASS 7.

Moritz

(attachments)

test_generalize_holes_grass64release.png

On Fri, Feb 6, 2015 at 10:23 AM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

[taking this over to grass-dev]

On 05/02/15 18:23, Markus Metz wrote:

On Thu, Feb 5, 2015 at 4:56 PM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

On 05/02/15 14:49, Markus Metz wrote:

On Thu, Feb 5, 2015 at 11:50 AM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

On 05/02/15 10:06, Markus Metz wrote:

v.generalize does not distinguish between outer and inner rings, it
simply goes through all boundaries and generalizes each one.

And this has always been the case or this is specific to GRASS7 ?

This has always been the case.

Then why doesn't there seem to be any generalization happening for the
hole
boundaries of the test dataset with grass64release ?

With the test dataset you provided, GRASS 6.4 does generalize the hole
boundaries. I do not have the problem vector of Robert, so I can not
say if the hole boundaries in that vector are generalized or not.

With a make distleaned, svn updated and recompiled grass64relase, using the
test data and the commands

v.generalize test method=douglas thresh=100 out=test_gen_100 --o
v.generalize test method=douglas thresh=500 out=test_gen_500 --o

I get the attached result (red = 100, orange=500). I don't see any
generalization in the holes as I do with the same commands in GRASS 7.

Hmm, I do get generalization of the holes in G64 (no local changes).

g.version -g
version=6.4.5svn
revision=64438M
date=2015

black: original, red: thresh=100, green: thresh=500

Markus M

(attachments)

g64_generalize_test.png