[postgis-users] Corner coordinates from Geometry

[Robert Hicks]

Works great! Thanks everyone!

On Tue, Nov 24, 2009 at 12:47 PM, Paul Ramsey <pramsey at opengeo.org> wrote:
> select st_x(st_centroid(geom)) as x, st_y(st_centroid(geom)) as y from mytable;
>
> On Tue, Nov 24, 2009 at 9:46 AM, Robert Hicks <robhyx at gmail.com> wrote:
>> Great thanks! I think either ST_PointOnSurface() or ST_Centroid()
>> should be fine, but now I need convert the geometry string into
>> latitude and longitude (Sorry, I should have been more clear before
>> what I was ultimately looking for).
>>
>> On Tue, Nov 24, 2009 at 12:40 PM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
>>> Ah, POINT(avg(X), avg(Y))...
>>>
>>> On Tue, Nov 24, 2009 at 9:38 AM, Kevin Neufeld <kneufeld at refractions.net> wrote:
>>>> Maxime van Noppen wrote:
>>>>>
>>>>> Paul Ramsey wrote:
>>>>>>
>>>>>> Use ST_Centroid() then. It's just the mid-point of the bbox, so it's
>>>>>> fast to calculate.
>>>>>
>>>>> It might be outside the polygon though.
>>>>>
>>>>
>>>> In which case, if it matters, use ST_PointOnSurface().
>>>>
>>>> Paul, just a clarification, I believe centroid calculates the geometric
>>>> centre of a geoemtry or "centre of mass" and not the mid-point of the bbox.
>>>>  Here are a few pictorial examples:
>>>> http://postgis.org/documentation/manual-1.5SVN/ST_Centroid.html
>>>>
>>>> -- Kevin
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>>
>>
>>
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