Problem from polylines to polygons

[Gio_ca]

Hi everybody,
I have just installed gvSIG because I need to convert a polyline feature (shape) into a polygons.
I used the sexante tool but I didn't get what I expected.
Basically I have an outer boundary (rectangle) and inside I have some ellipses and other polylines connecting on side of the boundary to another. It seems to me that the outer boundary is not recognized as a polyline. Indeed the polylines connecting two edges of the outer boundary are closed automatically after the conversion.

Can anybody help me on that?


This is the original image:



This is what I obtained after converting polylines into polygons with Sextante

[Benjamin Ducke]

I don't think you will be able to process this dataset
as polygons in GIS (any GIS, not just gvSIG).
It violates GIS topology rules to have overlapping polygons
in one layer.

Cheers,

Ben

----- Original Message -----

> Hi everybody,
> I have just installed gvSIG because I need to convert a polyline
> feature (shape) into a polygons.
> I used the sexante tool but I didn't get what I expected.
> Basically I have an outer boundary (rectangle) and inside I have some
> ellipses and other polylines connecting on side of the boundary to
> another. It seems to me that the outer boundary is not recognized as a
> polyline. Indeed the polylines connecting two edges of the outer
> boundary are closed
> automatically after the conversion.
>
> Can anybody help me on that?
>
>
> This is the original image:
> http://osgeo-org.1803224.n2.nabble.com/file/n6377472/original_polylines.jpg
>
>
> This is what I obtained after converting polylines into polygons with
> Sextante
> http://osgeo-org.1803224.n2.nabble.com/file/n6377472/converted_polygons.jpg
>
> -- View this message in context:
> http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6377472.html
> Sent from the gvSIG users mailing list archive at Nabble.com.
> _______________________________________________ Gvsig_internacional
> mailing list
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[Antonio Falciano]

Il 18/05/2011 13.51, Gio_ca ha scritto:

> Hi everybody,
> I have just installed gvSIG because I need to convert a polyline feature
> (shape) into a polygons.
> I used the sexante tool but I didn't get what I expected.
> Basically I have an outer boundary (rectangle) and inside I have some
> ellipses and other polylines connecting on side of the boundary to another.
> It seems to me that the outer boundary is not recognized as a polyline.
> Indeed the polylines connecting two edges of the outer boundary are closed
> automatically after the conversion.
>
> Can anybody help me on that?

Hi Giovanni,
have you tried the "Polygonize" tool in SEXTANTE? This algorithm
converts lines to polygons, considering only the edges which describe
closed areas and without returning overlapping polygons. Hope this helps!

Cheers,
Antonio

--
Antonio Falciano
http://www.linkedin.com/in/antoniofalciano

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[Gio_ca]

Hi Ben,
Actually ArcInfo tool "feature to polygon" managed to convert the file as I want, so considering the outer boundary as a polyline.

See the snapshot below when I highlighted one of the polygons out of the converted file. For example that polygon is not created by gvSIG.



Regards,
Giovanni

[Gio_ca]

Hi Antonio,
I just tried polygonize but this what I got:


I would like to get the same result as from ArcInfo...

Thanks

[Francisco José Peñarrubia]

Please, use a transparent fill. Maybe your polygons are down.
Can you clarify it?

El 18/05/2011 14:48, Gio_ca escribió:

> Hi Antonio,
> I just tried polygonize but this what I got:
> http://osgeo-org.1803224.n2.nabble.com/file/n6377637/polygonize.jpg
>
> I would like to get the same result as from ArcInfo...
>
> Thanks
>
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6377637.html
> Sent from the gvSIG users mailing list archive at Nabble.com.
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--
Fran Peñarrubia
Scolab
www.scolab.es

Asociación gvSIG
www.gvsig.com

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[Antonio Falciano]

Il 18/05/2011 14.48, Gio_ca ha scritto:
> Hi Antonio,
> I just tried polygonize but this what I got:
> http://osgeo-org.1803224.n2.nabble.com/file/n6377637/polygonize.jpg

And what do you obtain if you execute "Split polylines at nodes" tool
before "Polygonize"?

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[Gio_ca]

Hi checked the attribute tables and there are no polygons behind...

[Francisco José Peñarrubia]

Ok, then, check Antonio Falciano suggestion about split lines, and maybe
you will also need some snapping.
ArcInfo does this process when cleaning. (Removing dangles and snapping).

Hope it helps

Fran.

El 18/05/2011 15:08, Gio_ca escribió:
> Hi checked the attribute tables and there are no polygons behind...
>
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6377733.html
> Sent from the gvSIG users mailing list archive at Nabble.com.
> _______________________________________________
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--
Fran Peñarrubia
Scolab
www.scolab.es

Asociación gvSIG
www.gvsig.com

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[Gio_ca]

I tried what Antonio suggested but I got the same result...

[jorgepsantos2002]

Dude, it's very easy convert lines to polygons in gvSIG.You must try the Derivative Geometries.

Layer Menu - Derivative Geometries

I draw a similar feature and convert polyline to polygon with close geometries. See attatchment.

Best wishes,

_________________
Jorge Santos
Téc. em Geodésia e Cartografia
http://processamentodigital.blogspot.com/
http://twitter.com/jpsantos2002
Skype: jorgepsantos2002

2011/5/18 Gio_ca <[hidden email]>

I tried what Antonio suggested but I got the same result...

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[Gio_ca]

Thanks Jorge.
I can try but as long as I see from the attribute table of your attachment you just got 5 polygons while they should be 8. Probably you are missing polygons whose edges are both inner lines and part of the outer boundary.
See the image in the earlier messages that I produced with ArcInfo with a polygon highlighted in dark green. Do you have that polygon also in your map?

[Antonio Falciano]

Hi Jorge,
I have created 10 features with SEXTANTE "Create random vector layer"
tool and then applied both "Polygonize" and "Derivative geometries". It
seems that the results are quite different. The "derivative" polygons
overlap themselves, while the polygonized ones not. :-(
I'm agree with Fran. In this case, it seems that the external rectangle
doesn't intersect the internal lines at all, so it's surely a problem of
precision/snapping. SEXTANTE Polygonize tool nodes lines and merges them
using an enhanced precision in order to avoid topology exceptions,
however it doesn't snap "quite near" vertices. I think that we need more
robust topology checks in SEXTANTE and gvSIG in order to make them more
reliable and powerful in a production environment.

Cheers,
Antonio


Il 18/05/2011 17.30, Jorge Santos ha scritto:

> Dude, it's very easy convert lines to polygons in gvSIG.You must try
> the Derivative Geometries.
>
> *Layer Menu - Derivative Geometries*
>
> I draw a similar feature and convert polyline to polygon with close
> geometries. See attatchment.
>
> Best wishes,
>
> _________________
> Jorge Santos
> Téc. emGeodésiae Cartografia
> http://processamentodigital.blogspot.com/
> http://twitter.com/jpsantos2002
> Skype: jorgepsantos2002
>
> 2011/5/18 Gio_ca <[hidden email]
> <mailto:[hidden email]>>
>
>     I tried what Antonio suggested but I got the same result...
>
>     --
>     View this message in context:
>     http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6377788.html
>     Sent from the gvSIG users mailing list archive at Nabble.com.
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>     <mailto:[hidden email]>
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>
>
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[Antonio Falciano]

Giovanni,
please, can you send us in private your line layer? Thanks.

Cheers,
Antonio

Il 18/05/2011 17.42, Gio_ca ha scritto:

> Thanks Jorge.
> I can try but as long as I see from the attribute table of your attachment
> you just got 5 polygons while they should be 8. Probably you are missing
> polygons whose edges are both inner lines and part of the outer boundary.
> See my attachment in the earlier messages that I produced with ArcInfo with
> a polygon highlighted in dark green. Do you have that polygon also in your
> map?
>
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6378247.html
> Sent from the gvSIG users mailing list archive at Nabble.com.
> _______________________________________________
> Gvsig_internacional mailing list
> [hidden email]
> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>

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[Gio_ca]

Hi Antonio,
at the moment I am back home and I have all the files at the office. I will send the shape file to you tomorrow morning as soon as I get to the office.

Thank you very much,
Giovanni

[Gio_ca]

Hi Antonio,

Further to your request, I zipped and attached the shape file with polylines that I am trying to convert in a shapefile with 8 polygon features.

Thanks,

Giovanni

----Messaggio originale----
Da: [hidden email]
Data: 18/05/2011 17.53
A: "Gio_ca"<[hidden email]>
Ogg: Re: Problem from polylines to polygons

Giovanni,
please, can you send us in private your line layer? Thanks.

Cheers,
Antonio

Il 18/05/2011 17.42, Gio_ca ha scritto:

> Thanks Jorge.
> I can try but as long as I see from the attribute table of your attachment
> you just got 5 polygons while they should be 8. Probably you are missing
> polygons whose edges are both inner lines and part of the outer boundary.
> See my attachment in the earlier messages that I produced with ArcInfo with
> a polygon highlighted in dark green. Do you have that polygon also in your
> map?
>
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6378247.html
> Sent from the gvSIG users mailing list archive at Nabble.com.
> _______________________________________________
> Gvsig_internacional mailing list
> [hidden email]
> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>

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[Antonio Falciano]

Hi Giovanni,
there are some vertices that need to be snapped on the "rectangle". Just
a trick: you could extend all internal lines in order to intersect the
external rectangle and then polygonize them. Sorry for my approximation,
but it's a topological problem that needs further investigation and I
haven't enough time to study it now.

Cheers,
Antonio

Il 19/05/2011 9.52, Gio_ca ha scritto:

>
> Hi Antonio,
>
> Further to your request, I zipped and attached the shape file with
> polylines that I am trying to convert in a shapefile with 8 polygon
> features.
>
> Thanks,
>
> Giovanni
>
>
>
>     ----Messaggio originale----
>     Da: [hidden email] </user/SendEmail.jtp?type=node&node=6381007&i=0>
>     Data: 18/05/2011 17.53
>     A: "Gio_ca"<[hidden email]
>     </user/SendEmail.jtp?type=node&node=6381007&i=1>>
>     Ogg: Re: Problem from polylines to polygons
>
>     Giovanni,
>     please, can you send us in private your line layer? Thanks.
>
>     Cheers,
>     Antonio
>
>     Il 18/05/2011 17.42, Gio_ca ha scritto:
>
>     > Thanks Jorge.
>     > I can try but as long as I see from the attribute table of your
>     attachment
>     > you just got 5 polygons while they should be 8. Probably you are
>     missing
>     > polygons whose edges are both inner lines and part of the outer
>     boundary.
>     > See my attachment in the earlier messages that I produced with
>     ArcInfo with
>     > a polygon highlighted in dark green. Do you have that polygon
>     also in your
>     > map?
>     >
>     > --
>     > View this message in context:
>     http://osgeo-org.1803224.n2.nabble.com/Problem-from-polylines-to-polygons-tp6377472p6378247.html
>     > Sent from the gvSIG users mailing list archive at Nabble.com.
>     > _______________________________________________
>     > Gvsig_internacional mailing list
>     > [hidden email] </user/SendEmail.jtp?type=node&node=6378288&i=0>
>     > http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>     >
>     --
>     Antonio Falciano
>     http://www.linkedin.com/in/antoniofalciano
>
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