[postgis-devel] Problems with st_crosses postgis version 1.5

[David Potts]

Hi

I seem to have a problem with st_crosses function

I have two square grids, each aligned on top of each other, one grid
represents the other sub divided in to 4 quaters.  Each quater shares 2
common edges, the other 2 edges are within the square.

I had assumed that something like

select * from buoy_table b,quater_table q where
st_crosses(b.outline_geom,q.outline_geom)

would return every square in the quater grid within the buoy qrid, ie 4
squares from the quater grid to every single square in the buoy qrid

It returns nothing, any suggestions why ?


expressions like   st_intersections(st_buffer(q.outline_geom,-1),
s_buffer(b.outline_geom,-0.1)) will give me what I want, ie the 4 quater
squares per parent square but its very slow!


xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Any views expressed in this message are those of the individual sender,
except where the sender specifically states them to be the views of the
Pinan Software