[postgis-users] Area calculation oh two polygon that they are overlapping

[Paul Ramsey]

ST_Area(ST_Intersection(g1,g2)) ?

On Jan 10, 2008, at 8:23 AM, olivier.amram at free.fr wrote:

> Yes, but how do you calculate the area of the intersection ?
>
> Olivier.
>
> Selon Guido Lemoine <guido.lemoine at jrc.it>:
>
>> Your multipolygon is simply two rings of 3 by 3. Defining them
>> as multipolygon does do nothing for intersection, so the area is 18
>> (which is 9 + 9). You need to look up what intersection means.
>> For me, the intersection of the 2 polygons is the common area,
>> which is 4.
>>
>> GL
>>
>> olivier.amram at free.fr wrote:
>>> Hi,
>>>
>>> I'd like to compute the total area of polygon that intersects with  
>>> another
>>> polygon
>>>
>>> Polygon(0 0,0 3,3 3,3 0,0 0)
>>> Polygon(1 1,4 1,4 4,1 4,1 1)
>>>
>>> The total area is 14 but I don't find a solution to compute this  
>>> value.
>>>
>>> e.g. SELECT Area(GeomFromText('MultiPolygon( ((0 0,0 3,3 3,3 0,0  
>>> 0)),((1
>> 1,1 4,4
>>> 4,4 1,1 1)))')) --> 18
>>>
>>> Have you any idea ?
>>>
>>> Thank,
>>>
>>> Olivier.
>>>
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>>>
>>
>> --
>> ----------------------------------------------------------------
>> Guido Lemoine
>> Joint Research Centre, European Commission
>> Institute for the Protection and Security of the Citizen (IPSC)
>> Support to External Security
>> Via E. Fermi, 2749 TP 267 Ispra 21027 (VA), Italy
>> Tel. +39 0332 786239 (direct line) Fax. +39 0332 785154
>> WWW: http://ses.jrc.it
>> ----------------------------------------------------------------
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>> the views of the European Commission
>>
>>
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>
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