[gdal-dev] Re: can ogr2ogr split polygons that cross 180 degree longitude

[Hermann Peifer]

Hmm. With a fresh ogr2ogr from svn, I am running into this error:

ERROR 6: GEOS support not enabled.
ERROR 6: GEOS support not enabled.

Simply adding the configure option  --with-geos=yes doesn't help. The 
configure output is:

checking for geos-config... /home/peifer/local/FWTools/bin_safe/geos-config
checking for GEOS version >= 2.2.0... yes
checking for GEOSversion in -lgeos_c... no

Any hint how to fix this?

Hermann

Even Rouault wrote:
> Selon Hermann Peifer <peifer at gmx.eu>:
>
> I've finally added a new switch to ogr2ogr : -wrapdateline. See
> http://trac.osgeo.org/gdal/ticket/3158
>
>   
>> Even,
>>
>> Thanks for the possible algorithm.... but to be honest: some sort of
>> command line switch would be /somewhat more handy/, for non-programmers
>> like me.
>>
>> Hermann
>>
>> Even Rouault wrote:
>>     
>>> Selon Hermann Peifer <peifer at gmx.eu>:
>>>
>>> I think this should be prefectly doable with some code/script just using
>>>       
>> OGR
>>     
>>> API.
>>>
>>> Here's a possible algorithm :
>>>
>>> 1) Create a new empty WGS84 shapefile
>>> 1) Loop over features in the source shapefile (the one after reprojection
>>>       
>> to
>>     
>>> WGS84)
>>> 2a) If the polygon has points with longitudes both near 180° and near
>>>       
>> -180°,
>>     
>>> create a duplicate temporary polygon and add 360° to the negative
>>>       
>> longitudes.
>>     
>>> Compute the interescection with Geometry.Intersect (you need GEOS support)
>>>       
>> of
>>     
>>> that polygon with POLYGON((0 90,180 90,180 -90,0 -90,0 90)) and with
>>> POLYGON((180 90,360 90,360 -90,180 -90,180 90)). For the second
>>>       
>> intersection,
>>     
>>> substract 360° to the longitudes in order to get again longitudes in the
>>> [-180,180] range. Finally, write 2 new features into the output shapefile,
>>>       
>> or
>>     
>>> better, just one with the geometry being a multipolygon with the 2 parts.
>>> 2b) Otherwise, just copy the original feature into the output shapefile
>>>
>>> Best regards,
>>> Even
>>>
>>>
>>>       
>>>> Eric,
>>>>
>>>> I can't help much apart from confirming that the same happened to me
>>>> when trying to reproject Russia from LAEA to WGS84.
>>>>
>>>> My "solution" was to ask a colleague, who is using ESRI products to do
>>>> me a favour... :-(
>>>>
>>>> Hermann
>>>>
>>>>
>>>> Eric Muller wrote:
>>>>
>>>>         
>>>>> I am trying to reproject  shapefiles that represent Russia (from
>>>>>
>>>>>           
>> http://wagda.lib.washington.edu/DATA/geography/world/russia/download.html)
>>     
>>>>> from the original:
>>>>>
>>>>>     The map is Albers equal-area projection Clarke spheroid of1866 with
>>>>>     the first standard parallel 46 00 0.000, the second standard
>>>>>     parallel 73 00 0.000, the central meridian 84 00 0.000. The latitude
>>>>>     of the projection's origin is 60 00 0.000.  Units -- meters.
>>>>>
>>>>> to lat/long WGS84. I use the following command:
>>>>>
>>>>> ogr2ogr \
>>>>>     -s_srs '+proj=aea +ellps=clrk66 +lat_1=46.0 +lat_2=73.0 +lat_0=60.0
>>>>> +lon_0=84.0 +units=m +no_defs' \
>>>>>     -t_srs '+proj=latlong +ellps=WGS84 +datum=WGS84 +no_defs' \
>>>>>     rs_polbnda_${f}.shp rus${f}.shp
>>>>>
>>>>> I would like polygons that cross the 180 degree longitude to be split.
>>>>> It there a way to ask ogr2ogr to do that? What is the recommended way to
>>>>> do it, if not?
>>>>>
>>>>> Thanks,
>>>>> Eric.
>>>>>
>>>>>
>>>>> ------------------------------------------------------------------------
>>>>>
>>>>> _______________________________________________
>>>>> gdal-dev mailing list
>>>>> gdal-dev at lists.osgeo.org
>>>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>>>>
>>>>>           
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>>>>
>>>>
>>>>         
>>>       
>
>