[postgis-users] Analyse and erase the intersecting part of polygons

[Andreas Laggner]

Hello postgis-users,

i did an "append" of many geometries by inserting 70 tables in one table 
like this:

create table Atkisvegd(atkis_id integer, land character varying(2), oba 
integer) with oids;
select 
addgeometrycolumn('','atkisvegd','the_geom','31467','MULTIPOLYGON',2);

insert into Atkisvegd select gid, land, oba, the_geom from hh_veg1;
insert into Atkisvegd select gid, land, oba, the_geom from hh_veg2;
insert into Atkisvegd select gid, land, oba, the_geom from hh_veg3;
insert into Atkisvegd select gid, land, oba, the_geom from hh_veg4;
insert into Atkisvegd select gid, land, oba, the_geom from hh_veg5;

insert into Atkisvegd select gid, land, oba, the_geom from mv_veg1;
insert into Atkisvegd select gid, land, oba, the_geom from mv_veg2;
insert into Atkisvegd select gid, land, oba, the_geom from mv_veg3;
insert into Atkisvegd select gid, land, oba, the_geom from mv_veg4;
insert into Atkisvegd select gid, land, oba, the_geom from mv_veg5;

and so on..........

there should not exist any intersections, but actually there are 
intersections! (about 0.6% of the total area).
My AIM:
I want to eliminate the wrong part of the overlapping polygons (what´s 
wrong i can analyse with the attributes!).
For example i have many Polygons that are declared as "wet soils" and 
these often overlaps with other landuse
(98.7% of the overlapping area is "wet soils"). I derived this 
informations from the dataset in ArcGis.

adios Andreas


-- 
Dipl. Geoökologe Andreas Laggner
Institut für Ländliche Räume (LR)
Bundesforschungsanstalt für Landwirtschaft (FAL)

Institute of Rural Studies
Federal Agricultural Research Centre (FAL)

Bundesallee 50
D-38116 Braunschweig

Tel.: (+49) (0)531 596 5515
Fax: (+49) (0)531 596 5599
E-mail: andreas.laggner at fal.de
Homepage: http://www.lr.fal.de/