SELECT ST_Area(ST_Intersection(GeomFromText('Polygon((0 0,0 3,3 3,3 0,0
0))'),
GeomFromText('Polygon((1 1,1 4,4 4,4 1,1 1))'))) --> 4 (QED)
SELECT ST_Area(ST_Union(GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))'),
GeomFromText('Polygon((1 1,1 4,4 4,4 1,1 1))'))) --> 14
Paul Ramsey wrote:
ST_Area(ST_Intersection(g1,g2)) ?
On Jan 10, 2008, at 8:23 AM, [EMAIL PROTECTED] wrote:
Yes, but how do you calculate the area of the intersection ?
Olivier.
Selon Guido Lemoine <[EMAIL PROTECTED]>:
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
[EMAIL PROTECTED] 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
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Tel. +39 0332 786239 (direct line) Fax. +39 0332 785154
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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
----------------------------------------------------------------
Disclaimer:
Views expressed are those of the individual and do not represent
the views of the European Commission
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