[postgis-users] Intersect Query Issue

Jerod Clabaugh jclabaugh at mac.com
Wed Jun 1 15:01:38 PDT 2005


All:

I am trying to get the area as acres from the overlap of 2 polygons. 
I have 2 polygon tables, shape.pa and shape_incursion_2005.  I used 
the query below and got an answer but its not correct.  Its not 
providing the correct area for the overlapping area post-clipping, 
but rather pre-clipping.

SELECT (area(shape_incursion_2005.the_geom)* 0.0002471) as acres, 
intersection(shape_incursion_2005.the_geom, shape_pa.the_geom) FROM 
shape_pa, shape_incursion_2005 WHERE 
intersects(shape_incursion_2005.the_geom, shape_pa.the_geom) AND 
shape_pa.name = 'Caracol'

In ArcGIS, I would select the polygon I wanted to compare 
(shape_pa.name = 'Caracol') and then clip the other table's 
overlapping polygons onto it and then calculate the area...

Any ideas on what I am doing wrong?

Thanks in advance,

Jerod Clabaugh



More information about the postgis-users mailing list