[gdal-dev] more than one linearring object in the geometry but with all linerring objects having zero points?

[Frank Warmerdam]

Chao,

I suspect you have a multipolygon.  So each subgeometry is a polygon
on which there are in turn subgeometries which are rings.

By the way, if you just print the geometry in python you should get
the "Well Known Text" representation which can be explanatory.

Best regards,
Frank



On Thu, Mar 28, 2013 at 9:58 AM, Chao YUE <chaoyuejoy at gmail.com> wrote:
> Dear all,
>
> I try to read fire polygon shapefile by ogr (beginner level), I referred to
> some sources online:
> http://geoinformaticstutorial.blogspot.fr/2012/10/accessing-vertices-from-polygon-with.html
> http://gis.stackexchange.com/questions/8144/get-all-vertices-of-a-polygon-using-ogr-and-python
>
> However, both the links are incomplete as I have polygons who have more than
> one linearring objects, which
> fianally turns out to have hole inside the polygon.
>
> But I have another strange issue, is that there are some polygons with more
> than one linearring object,
> but all the rings have zero points. However, the fire size of the polygon is
> not zero, and when I checked
> the same polygon in ArcGIS, there is really a shape! could anyone point out
> I miss something?
> thanks!!
>
> In [28]:
>
> feature = layer.GetFeature(276)
>
> geo = feature.GetGeometryRef()
>
> geo.GetGeometryCount()
>
> Out[28]:
>
> 2
>
> In [29]:
>
> ring = geo.GetGeometryRef(0)
>
> ring.GetPointCount()
>
> Out[29]:
>
> 0
>
> In [31]:
>
> ring = geo.GetGeometryRef(1)
>
> ring.GetPointCount()
>
> Out[31]:
>
> 0
>
> In [34]:
>
> feature.items()['SIZE_HA']
>
> Out[34]:
>
> 13041.187
>
>
> Chao
> --
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
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>
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