[postgis-users] Point inside a polygon

[Larry Reeder]

Another thing to be aware of with ST_PointOnSurface is it can return a
point that's on the boundary of polygon, but *not inside* the polygon, so
that ST_Within(St_PointOnSurface(surface), surface) returns false.  That's
bitten me before, but may be OK for your purposes.

       -Larry




On Fri, May 2, 2014 at 1:38 PM, Åsmund Tokheim <asmundto at gmail.com> wrote:

> Hi
>
> You can use st_closestpoint(geom, st_centroid(geom)) to make sure that the
> returned point is in most circumstances at or near the centroid, and always
> at least on the boundary of the polygon. While st_pointonsurface certainly
> will be faster, it will often choose a more random point on the surface.
>
> Åsmund
>
>
> On Fri, May 2, 2014 at 12:45 PM, Nicolas Ribot <nicolas.ribot at gmail.com>wrote:
>
>> Hi,
>>
>> Use st_pointOnSurface (
>> http://postgis.net/docs/manual-2.1/ST_PointOnSurface.html)
>>
>> Nicolas
>>
>>
>> On 2 May 2014 06:32, J.Alejandro Martinez Linares <islanis at infomed.sld.cu
>> > wrote:
>>
>>> Hi people, i need your help, i was using st_centroid to get a point that
>>> be inside a polygon butr st_centroid got a property  that is a problem to
>>> me, it returns a point that not always is inside the polygon, cause when
>>> the polygon has an irregular form, the point that st_centroid is outside
>>> the polygon, and i need a function that do a similar thing that st_centroid
>>> but i need that the point it returns always be inside the polygon, is there
>>> a function that do that?
>>>
>>> cheers.
>>>
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