Re: [gdal-dev] Polygonizer / Lines

2013-03-18 Thread Alisson Barbosa 
Yes Peter. I'm trying to get the Thiessen polygons.

Thanks for the tips, but the Polygonize method of OGRMultiLineString worked
for me.

Thank you.

2013/3/15 Peter Halls p.ha...@york.ac.uk

 Alisson,

  in vector mode, where you are working with linestrings, the procedure
 is as described in Stephen Wise's book, GIS Basics (Taylor  Francis, 2002)
 chapters 2 - 4.  You will need to compute the intersection of all the lines
 (Chapter 3), split them at the intersections and either duplicate the
 common boundary segments or (my preferred way) build a simple topology
 table that lists each line segment required for each polygon.  That way you
 can still output the set of complete polygons to a shapefile (no
 topology).  You will need to take account of the fact that some line
 segments must be reversed when building the polygon.

 Does that help?

 Best wishes,

 Peter


 On 15 March 2013 12:50, Alisson Barbosa alisson.u...@gmail.com wrote:

 Thank you Chaitanya,

 I had read the explanation of Peter Halls. But that was *raster
 polygonization*. I am currently working with another type: *
 polygonization of OGRLineStrings*.

 My question was because i was not able to polygonize using the mentioned
 method. I created an OGRMultiLineString or an OGRGeometryCollection and
 added geometries (many OGRLineStrings) by addGeometry or
 addGeometryDirectly methods. But the polygonization always returned null.

 I solved using this:

 OGRMultiLineString *mls = new OGRMultiLineString();
 OGRMultiLineString* pTemp = NULL;
 while(...) //iteration of lines
 {
 //creation of line
 pTemp = static_castOGRMultiLineString*(mls-Union(line));
 if (pTemp != NULL)
 {
 if( mls != NULL)
 {
 if( mls-getNumGeometries()  0)
 delete mls;
 }
 mls = pTemp;
 }
 }

 Thanks,

 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Alisson,

 You can refer to the method's documentation here:
 http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec

 The mechanism of this operation was already explained Peter Halls in
 this mailing list[1]. GEOS does a good job identifying line strings
 touching at end points and then combining them to make rings and then
 polygons.

 However, it's your job to ensure that all the line strings passed to the
 method are part of a single polygon.

 [1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html


 On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa 
 alisson.u...@gmail.com wrote:

 Can you explain a bit better?


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com
 wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




 --
 Best regards,
 Chaitanya kumar CH.

 +91-9494447584
 17.2416N 80.1426E




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --

 
 Peter J Halls, GIS Advisor  Team Leader Applications Support and
 Training,
Information Directorate, University of York
 Telephone: 01904 323806 Fax: 01904 323740
 Snail mail: Harry Fairhurst Building, University of York,
 Heslington, York YO10 5DD
 This message has the status of a private and personal communication

 




-- 
Alisson Barbosa
Systems Analyst - FUNCEME
M.Sc. in Computer Science - MACC
Graduate in Computer Science  - UECE
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Re: [gdal-dev] Polygonizer / Lines

2013-03-15 Thread Alisson Barbosa 
Thank you Chaitanya,

I had read the explanation of Peter Halls. But that was *raster
polygonization*. I am currently working with another type: *polygonization
of OGRLineStrings*.

My question was because i was not able to polygonize using the mentioned
method. I created an OGRMultiLineString or an OGRGeometryCollection and
added geometries (many OGRLineStrings) by addGeometry or
addGeometryDirectly methods. But the polygonization always returned null.

I solved using this:

OGRMultiLineString *mls = new OGRMultiLineString();
OGRMultiLineString* pTemp = NULL;
while(...) //iteration of lines
{
//creation of line
pTemp = static_castOGRMultiLineString*(mls-Union(line));
if (pTemp != NULL)
{
if( mls != NULL)
{
if( mls-getNumGeometries()  0)
delete mls;
}
mls = pTemp;
}
}

Thanks,

2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Alisson,

 You can refer to the method's documentation here:
 http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec

 The mechanism of this operation was already explained Peter Halls in this
 mailing list[1]. GEOS does a good job identifying line strings touching at
 end points and then combining them to make rings and then polygons.

 However, it's your job to ensure that all the line strings passed to the
 method are part of a single polygon.

 [1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html


 On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa 
 alisson.u...@gmail.comwrote:

 Can you explain a bit better?


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




 --
 Best regards,
 Chaitanya kumar CH.

 +91-9494447584
 17.2416N 80.1426E




-- 
Alisson Barbosa
Systems Analyst - FUNCEME
M.Sc. in Computer Science - MACC
Graduate in Computer Science  - UECE
___
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Re: [gdal-dev] Polygonizer / Lines

2013-03-15 Thread Chaitanya kumar CH 
Alisson,

Can you provide a sample dataset that didn't work?


On Fri, Mar 15, 2013 at 6:20 PM, Alisson Barbosa alisson.u...@gmail.comwrote:

 Thank you Chaitanya,

 I had read the explanation of Peter Halls. But that was *raster
 polygonization*. I am currently working with another type: *polygonization
 of OGRLineStrings*.

 My question was because i was not able to polygonize using the mentioned
 method. I created an OGRMultiLineString or an OGRGeometryCollection and
 added geometries (many OGRLineStrings) by addGeometry or
 addGeometryDirectly methods. But the polygonization always returned null.

 I solved using this:

 OGRMultiLineString *mls = new OGRMultiLineString();
 OGRMultiLineString* pTemp = NULL;
 while(...) //iteration of lines
 {
 //creation of line
 pTemp = static_castOGRMultiLineString*(mls-Union(line));
 if (pTemp != NULL)
 {
 if( mls != NULL)
 {
 if( mls-getNumGeometries()  0)
 delete mls;
 }
 mls = pTemp;
 }
 }

 Thanks,


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Alisson,

 You can refer to the method's documentation here:
 http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec

 The mechanism of this operation was already explained Peter Halls in this
 mailing list[1]. GEOS does a good job identifying line strings touching at
 end points and then combining them to make rings and then polygons.

 However, it's your job to ensure that all the line strings passed to the
 method are part of a single polygon.

 [1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html


 On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa alisson.u...@gmail.com
  wrote:

 Can you explain a bit better?


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




 --
 Best regards,
 Chaitanya kumar CH.

 +91-9494447584
 17.2416N 80.1426E




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




-- 
Best regards,
Chaitanya kumar CH.

+91-9494447584
17.2416N 80.1426E
___
gdal-dev mailing list
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Re: [gdal-dev] Polygonizer / Lines

2013-03-15 Thread Peter Halls 
Alisson,

 in vector mode, where you are working with linestrings, the procedure
is as described in Stephen Wise's book, GIS Basics (Taylor  Francis, 2002)
chapters 2 - 4.  You will need to compute the intersection of all the lines
(Chapter 3), split them at the intersections and either duplicate the
common boundary segments or (my preferred way) build a simple topology
table that lists each line segment required for each polygon.  That way you
can still output the set of complete polygons to a shapefile (no
topology).  You will need to take account of the fact that some line
segments must be reversed when building the polygon.

Does that help?

Best wishes,

Peter

On 15 March 2013 12:50, Alisson Barbosa alisson.u...@gmail.com wrote:

 Thank you Chaitanya,

 I had read the explanation of Peter Halls. But that was *raster
 polygonization*. I am currently working with another type: *polygonization
 of OGRLineStrings*.

 My question was because i was not able to polygonize using the mentioned
 method. I created an OGRMultiLineString or an OGRGeometryCollection and
 added geometries (many OGRLineStrings) by addGeometry or
 addGeometryDirectly methods. But the polygonization always returned null.

 I solved using this:

 OGRMultiLineString *mls = new OGRMultiLineString();
 OGRMultiLineString* pTemp = NULL;
 while(...) //iteration of lines
 {
 //creation of line
 pTemp = static_castOGRMultiLineString*(mls-Union(line));
 if (pTemp != NULL)
 {
 if( mls != NULL)
 {
 if( mls-getNumGeometries()  0)
 delete mls;
 }
 mls = pTemp;
 }
 }

 Thanks,

 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Alisson,

 You can refer to the method's documentation here:
 http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec

 The mechanism of this operation was already explained Peter Halls in this
 mailing list[1]. GEOS does a good job identifying line strings touching at
 end points and then combining them to make rings and then polygons.

 However, it's your job to ensure that all the line strings passed to the
 method are part of a single polygon.

 [1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html


 On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa alisson.u...@gmail.com
  wrote:

 Can you explain a bit better?


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




 --
 Best regards,
 Chaitanya kumar CH.

 +91-9494447584
 17.2416N 80.1426E




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




-- 

Peter J Halls, GIS Advisor  Team Leader Applications Support and Training,
   Information Directorate, University of York
Telephone: 01904 323806 Fax: 01904 323740
Snail mail: Harry Fairhurst Building, University of York,
Heslington, York YO10 5DD
This message has the status of a private and personal communication

___
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[gdal-dev] Polygonizer / Lines

2013-03-14 Thread Alisson Barbosa 
Hi friends,

I have a set of OGRLineStrings and an OGRLinearRing with many
intersections. I would like to polygonize this set of lines. Can anybody
help me?

Best regards,
-- 
Alisson Barbosa
Systems Analyst - FUNCEME
M.Sc. in Computer Science - MACC
Graduate in Computer Science  - UECE
___
gdal-dev mailing list
gdal-dev@lists.osgeo.org
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Re: [gdal-dev] Polygonizer / Lines

2013-03-14 Thread Chaitanya kumar CH 
Allison,

Check out OGRGeometry::Polygonize()

The result depends on the type of intersections in your lines.

--
Best regards,
Chaitanya Kumar CH
On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev

___
gdal-dev mailing list
gdal-dev@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/gdal-dev

Re: [gdal-dev] Polygonizer / Lines

2013-03-14 Thread Alisson Barbosa 
Can you explain a bit better?

2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




-- 
Alisson Barbosa
Systems Analyst - FUNCEME
M.Sc. in Computer Science - MACC
Graduate in Computer Science  - UECE
___
gdal-dev mailing list
gdal-dev@lists.osgeo.org
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Re: [gdal-dev] Polygonizer / Lines

2013-03-14 Thread Chaitanya kumar CH 
Alisson,

You can refer to the method's documentation here:
http://www.gdal.org/ogr/classOGRGeometry.html#a674319670e735bf6d4049300096157ec

The mechanism of this operation was already explained Peter Halls in this
mailing list[1]. GEOS does a good job identifying line strings touching at
end points and then combining them to make rings and then polygons.

However, it's your job to ensure that all the line strings passed to the
method are part of a single polygon.

[1]: http://lists.osgeo.org/pipermail/gdal-dev/2012-November/034793.html


On Thu, Mar 14, 2013 at 11:58 PM, Alisson Barbosa alisson.u...@gmail.comwrote:

 Can you explain a bit better?


 2013/3/14 Chaitanya kumar CH chaitanya...@gmail.com

 Allison,

 Check out OGRGeometry::Polygonize()

 The result depends on the type of intersections in your lines.

 --
 Best regards,
 Chaitanya Kumar CH
 On 14 Mar 2013 21:53, Alisson Barbosa alisson.u...@gmail.com wrote:

 Hi friends,

 I have a set of OGRLineStrings and an OGRLinearRing with many
 intersections. I would like to polygonize this set of lines. Can anybody
 help me?

 Best regards,
 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE


 ___
 gdal-dev mailing list
 gdal-dev@lists.osgeo.org
 http://lists.osgeo.org/mailman/listinfo/gdal-dev




 --
 Alisson Barbosa
 Systems Analyst - FUNCEME
 M.Sc. in Computer Science - MACC
 Graduate in Computer Science  - UECE




-- 
Best regards,
Chaitanya kumar CH.

+91-9494447584
17.2416N 80.1426E
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