[postgis-users] Difficult Problem with Polygons

[Francois Hugues]

Hi,

1. Does st_touches not work for that ?

2. What do you mean by below ? south from the line ? St_distance should help you to find the closer one from Q.

Hugues.


-------- Message d'origine--------
De: postgis-users-bounces at postgis.refractions.net de la part de Ed Linde
Date: lun. 29/10/2012 09:33
À: PostGIS Users Discussion
Objet : [postgis-users] Difficult Problem with Polygons
 
Hi All,
I need help with 2 hard problems. I store triangles in a table as POLYGON.

1. I want to know for a given triangle, which triangles share an edge
(adjacent) with this triangle.

2. Then I have a line that cuts through a triangle's face and a point Q,
away from this line and
triangle. I would like to know amongst the neighbours of the triangle
(calculated in 1),
which ones fall *below* the line and closer to the point Q (where Q is the
generator of a Voronoi cell).
And also the set of triangles that are *above* the line and further from Q.

Any suggestions as to how I can go about achieving this in postgis 2.0?

Cheers,
Ed

-------------- next part --------------
A non-text attachment was scrubbed...
Name: winmail.dat
Type: application/ms-tnef
Size: 3248 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20121029/f9f42545/attachment.bin>