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From: Stefan Steiniger <sstein@ge...>  20080711 00:22:48

Hei, Today I started some work on analysing and later generalising (i.e. simplification) of polygon layers where the polygons form a mosaic (tesselation). So any operation on the boundaries requires that topologic neighbourhood must be observed. I.e. to simplify an outline I need to simplify the common boundary of two polygons. I have now written a "polygon neighborhood graph" and try now to extract the common boundary. Unfortunately the Jts intersection command results in linestrings that are rather line segments. So I need to paste them together again. Does anybody knows a function for that? I tested union, and it seems to create again a MultiLineStrings instead of a unified line. The only tool that comes to my mind so far is Larry's /ISA's "blend lines". Any other suggestions? Stefan 
From: Larry Becker <becker.larry@gm...>  20080711 00:58:20
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Hi Stefan, How about com.vividsolutions.jts.operation.polygonize? That seems to be what it was intended to do. regards, Larry On Thu, Jul 10, 2008 at 7:21 PM, Stefan Steiniger <sstein@...> wrote: > Hei, > > Today I started some work on analysing and later generalising (i.e. > simplification) of polygon layers where the polygons form a mosaic > (tesselation). So any operation on the boundaries requires that > topologic neighbourhood must be observed. I.e. to simplify an outline I > need to simplify the common boundary of two polygons. > > I have now written a "polygon neighborhood graph" and try now to extract > the common boundary. Unfortunately the Jts intersection command results > in linestrings that are rather line segments. So I need to paste them > together again. Does anybody knows a function for that? > > I tested union, and it seems to create again a MultiLineStrings instead > of a unified line. The only tool that comes to my mind so far is Larry's > /ISA's "blend lines". > > Any other suggestions? > > Stefan > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel >  http://amusingprogrammer.blogspot.com/ 
From: Stefan Steiniger <sstein@ge...>  20080711 01:29:29

Hei Larry, mhm.. maybe I could not really express what I want to do. I have already polygons  and want to derive the common boundary between two polygon as "one Linestring". So I need to concatenate the pieces that intersection() does return. Or are you proposing to simply work with the (out)lines instead of the complete polygon? Not sure if that would be an advantage, as I also need to clean up the data from double edges. Not sure... Stefan Larry Becker wrote: > Hi Stefan, > > How about com.vividsolutions.jts.operation.polygonize? That seems to > be what it was intended to do. > > regards, > Larry > > > > On Thu, Jul 10, 2008 at 7:21 PM, Stefan Steiniger <sstein@... > <mailto:sstein@...>> wrote: > > Hei, > > Today I started some work on analysing and later generalising (i.e. > simplification) of polygon layers where the polygons form a mosaic > (tesselation). So any operation on the boundaries requires that > topologic neighbourhood must be observed. I.e. to simplify an outline I > need to simplify the common boundary of two polygons. > > I have now written a "polygon neighborhood graph" and try now to extract > the common boundary. Unfortunately the Jts intersection command results > in linestrings that are rather line segments. So I need to paste them > together again. Does anybody knows a function for that? > > I tested union, and it seems to create again a MultiLineStrings instead > of a unified line. The only tool that comes to my mind so far is Larry's > /ISA's "blend lines". > > Any other suggestions? > > Stefan > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > <mailto:Jumppilotdevel@...> > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel > > > > >  > http://amusingprogrammer.blogspot.com/ > > >  > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > > >  > > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel 
From: Michael Michaud <michael.michaud@fr...>  20080711 07:02:21

Hi Stefan, Did you try the planar graph plugin. Last time I had such a problem, I created a planar graph from my polygon layer, simplified the resulting edge layer created a new planar graph (or polygonize) from the simplified edges layer. Otherwise, to create linestrings from linesegments, use linemerge (I think I added an option to union or union by attribute to merge linesegments if needed) Michaël Stefan Steiniger a écrit : > Hei, > > Today I started some work on analysing and later generalising (i.e. > simplification) of polygon layers where the polygons form a mosaic > (tesselation). So any operation on the boundaries requires that > topologic neighbourhood must be observed. I.e. to simplify an outline I > need to simplify the common boundary of two polygons. > > I have now written a "polygon neighborhood graph" and try now to extract > the common boundary. Unfortunately the Jts intersection command results > in linestrings that are rather line segments. So I need to paste them > together again. Does anybody knows a function for that? > > I tested union, and it seems to create again a MultiLineStrings instead > of a unified line. The only tool that comes to my mind so far is Larry's > /ISA's "blend lines". > > Any other suggestions? > > Stefan > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel > > > 
From: Stefan Steiniger <sstein@ge...>  20080711 07:23:39

Salut Michael, Michael Michaud schrieb: > Hi Stefan, > > Did you try the planar graph plugin. > Last time I had such a problem, I created a planar graph from my polygon > layer, > simplified the resulting edge layer > created a new planar graph (or polygonize) from the simplified edges layer. alright that could be a good idea, to use the created edge layer. I will check that (... especially as I wanted to have some generalization results for a presentation in about 3 weeks). > > Otherwise, to create linestrings from linesegments, use linemerge (I > think I added an option to union or union by attribute to merge > linesegments if needed) aha.. even better :) [because at some point I may need to work with my personal polygon graph when (hopefully) starting to implement object based generalization procedures] thank you Michael and Larry Stefan PS: still watching the Linus Video [sometimes he is not very convincing, just by a lack of hard arguments from my point of view.. but the questions from the audience are also not that clear to me] > > Michaël > > Stefan Steiniger a écrit : >> Hei, >> >> Today I started some work on analysing and later generalising (i.e. >> simplification) of polygon layers where the polygons form a mosaic >> (tesselation). So any operation on the boundaries requires that >> topologic neighbourhood must be observed. I.e. to simplify an outline I >> need to simplify the common boundary of two polygons. >> >> I have now written a "polygon neighborhood graph" and try now to extract >> the common boundary. Unfortunately the Jts intersection command results >> in linestrings that are rather line segments. So I need to paste them >> together again. Does anybody knows a function for that? >> >> I tested union, and it seems to create again a MultiLineStrings instead >> of a unified line. The only tool that comes to my mind so far is Larry's >> /ISA's "blend lines". >> >> Any other suggestions? >> >> Stefan >> >>  >> Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! >> Studies have shown that voting for your favorite open source project, >> along with a healthy diet, reduces your potential for chronic lameness >> and boredom. Vote Now at http://www.sourceforge.net/community/cca08 >> _______________________________________________ >> Jumppilotdevel mailing list >> Jumppilotdevel@... >> https://lists.sourceforge.net/lists/listinfo/jumppilotdevel >> >> >> > > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel > > 
From: Stefan Steiniger <sstein@ge...>  20080714 19:56:36

So.. I tried it now with the planar graph. Unfortunately an error did occur with my data and the function also returns several overlapping edges instead one for touching polygons. However, I could use the LineMerger that was also used in PlanarGraph by Michael and I get now what I want :) Next steps are now to let the generalization work on the edges and then to regenerate the polygons. stefan Michael Michaud wrote: > Hi Stefan, > > Did you try the planar graph plugin. > Last time I had such a problem, I created a planar graph from my polygon > layer, > simplified the resulting edge layer > created a new planar graph (or polygonize) from the simplified edges layer. > > Otherwise, to create linestrings from linesegments, use linemerge (I > think I added an option to union or union by attribute to merge > linesegments if needed) > > Michaël > > Stefan Steiniger a écrit : >> Hei, >> >> Today I started some work on analysing and later generalising (i.e. >> simplification) of polygon layers where the polygons form a mosaic >> (tesselation). So any operation on the boundaries requires that >> topologic neighbourhood must be observed. I.e. to simplify an outline I >> need to simplify the common boundary of two polygons. >> >> I have now written a "polygon neighborhood graph" and try now to extract >> the common boundary. Unfortunately the Jts intersection command results >> in linestrings that are rather line segments. So I need to paste them >> together again. Does anybody knows a function for that? >> >> I tested union, and it seems to create again a MultiLineStrings instead >> of a unified line. The only tool that comes to my mind so far is Larry's >> /ISA's "blend lines". >> >> Any other suggestions? >> >> Stefan >> >>  >> Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! >> Studies have shown that voting for your favorite open source project, >> along with a healthy diet, reduces your potential for chronic lameness >> and boredom. Vote Now at http://www.sourceforge.net/community/cca08 >> _______________________________________________ >> Jumppilotdevel mailing list >> Jumppilotdevel@... >> https://lists.sourceforge.net/lists/listinfo/jumppilotdevel >> >> >> > > >  > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Jumppilotdevel mailing list > Jumppilotdevel@... > https://lists.sourceforge.net/lists/listinfo/jumppilotdevel > > 
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