[gdal-dev] OSGeo.OGR.Geometry: Union the mutiple geometries at a time

[jratike80]

Hi,

I can't imagine any connection between Union and Convex/Concave hull. Union
of the points in the example image is a MultiPoint geometry. The hull is a
single geometry that encloses the input geometries, in this case it is a
polygon. There is no need to consider hulls when doing Union. Generally
hulls are useful things and I believe that GDAL supports convex hull through
GEOS. Convex hull is well defined and there is only one correct solution
when it is computed. It is also included in the OGC Simple Feature standard. 
Concave hulls are not as well defined and different implementations give
different results. If you need concave hull I would recommend PostGIS
https://postgis.net/docs/ST_ConcaveHull.html.

-Jukka Rahkonen- 

 


MRRAJESH wrote
> I am referring to the below image -
> 
> <http://osgeo-org.1560.x6.nabble.com/file/t386336/Convex_ConcaveHull.png> 
> 
> 
> 
> 
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