[gdal-dev] MULTILINESTRING to MULTIPOLYGON using ogr2ogr

Tue Nov 27 03:58:08 PST 2012

Thanks for all of your responses...
we're a trying some of your suggestions, using some tools to accomplish
this task.
I think we're close enough now. (the polygon shapefile is almost correctly
generated from a shape with a bunch of lines which compose closed
boundaries of polygons).

On Mon, Nov 26, 2012 at 2:53 PM, Joaquim Luis <jluis at ualg.pt> wrote:

>  GMT5 has a tool called gmtstitch that could perhaps help doing the job,
> but I never played enough with it to be more positive about its capacities.
>
> Joaquim
>
>
> I want a command line tool to do the same thing that "Feature to Polygon"
> of ArcGIS or Polygonizer plugin of Quantum GIS does. Is there any tool for
> this?
>
> 2012/11/26 Peter Halls <p.halls at york.ac.uk>
>
>> Alisson, Hugo,
>>
>>      I think a reason for the lack of response is that the operation
>> you need is a tad more involved than is supported by ogr2ogr - which
>> performs simple geometrical operations but is really designed to
>> perform format translations.
>>
>>     To go from a spaghetti of lines to polygons requires the
>> identification of each future polygon boundary, the assembly of the
>> polygon boundary, ensuring that it closes and writing out the new
>> polygon.  This much ogr2ogr does.  To go to multipolygons, however,
>> requires the further assembly of the related polygons into a combined
>> polygon - for example, islands in a lake.  All of this relies on the
>> existence of attribute values to identify what belongs to what.
>> Further complication is involved if the resultant polygons overlap and
>> it is required that these overlaps be identified, although this is not
>> required for a polygon shapefile.
>>
>>     As this process may require intelligence based upon more complex
>> attribute relationships, it is probably the case that a program
>> (Python, Java, C++, etc) is required to implement the specific logic
>> required.
>>
>>     If you want to read up on the operations involved, one of the most
>> approachable texts is 'GIS Basics' by Steve Wise (Taylor & Francis,
>> 2002).  The good news is that there are calls in the OGR API to
>> implement each of the steps involved.
>>
>> Best wishes,
>>
>> Peter
>>
>> On 26 November 2012 12:24, Hugo Benicio <hbobenicio at gmail.com> wrote:
>> > I'm facing a similar problem when trying to convert a shapefile
>> containing
>> > lines to a shapefile containing polygons.
>> > No progress.
>> > If you solve it, please, let me know!
>> >
>> > Thanks in advance.
>> >
>> >
>> > On Mon, Nov 26, 2012 at 8:47 AM, Alisson Barbosa <
>> alisson.uece at gmail.com>
>> > wrote:
>> >>
>> >> Can anybody help me?
>> >>
>> >>
>> >> 2012/11/23 Alisson Barbosa <alisson.uece at gmail.com>
>> >>>
>> >>> Hi friends,
>> >>>
>> >>> I would like to transform a shape with multilinestring in a shape with
>> >>> polygons using ogr2ogr.
>> >>>
>> >>> Polygon to multilinestring, I use:
>> >>> ogr2ogr -f "ESRI Shapefile" -overwrite "C:/Users/Alisson/Basins3.shp"
>> >>> "C:/Users/Alisson/Basins2.shp" -sql "SELECT * FROM Basins2"
>> -skipfailures
>> >>> -nlt MULTILINESTRING
>> >>>
>> >>> This works.
>> >>>
>> >>> Multilinestring to multipolygon, I use:
>> >>> ogr2ogr -f "ESRI Shapefile" -overwrite "C:/Users/Alisson/polygon.shp"
>> >>> "C:/Users/AlissonContorno30.shp" -sql "SELECT * FROM Contorno30"
>> >>> -skipfailures -nlt MULTIPOLYGON
>> >>>
>> >>> But, this error appears:
>> >>> ERROR 1: Attempt to write non-polygon (LINESTRING) geometry to POLYGON
>> >>> type shapefile.
>> >>>
>> >>> Can you help me?
>> >>>
>> >>> Best regards,
>> >>> --
>> >>> Alisson Barbosa
>> >>> Systems Analyst - FUNCEME
>> >>> M.Sc. in Computer Science - MACC
>> >>> Graduate in Computer Science  - UECE
>> >>>
>> >>>
>> >>
>> >>
>> >>
>> >> --
>> >> Alisson Barbosa
>> >> Systems Analyst - FUNCEME
>> >> M.Sc. in Computer Science - MACC
>> >> Graduate in Computer Science  - UECE
>> >>
>> >>
>> >>
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>> >
>> >
>> >
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>>
>>
>>  --
>>
>> ----------------------------------------------------------------------------------------------------------------
>> 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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