[postgis-devel] Trying to get st_convexhull to return a bonduing box for a collection of linestrings

[Leknín Řepánek]

What about ST_Polygonize?

On Sun, Jan 03, 2016 at 08:12:28PM +0000, dave.potts at pinan.co.uk wrote:
> Hi
> 
> I have  postgis table which includes a series of Linestrings,  I am trying to
> create a single geometry that includes only the outside layer of line strings.
> 
> An example would be if the line strings described  digital 8, formed from
> squares two boxes,  I would want something looked like a rectangle, 
> 
> I have tried things like 
> 
>  select st_convexhull( st_union(st_startpoint(the_geom),st_endpoint(the_geom)))
>  from bar_table
> 
> I assumed that I would get a polygon with the middle bar removed, what I got
> was a collection of linestrings
> 
> Has anybody got any suggestions?
> 
> regards
> 
> 
> Dave.

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