[Qgis-user] ftools union issue: duplicating polygons

[Ivan Santiago]

Hello all:

I'm having some problems using union from fTools 0.6.2, specifically with Union.

I have three polygon layers:
a municipality area
1980 urban areas
1990 urban areas

The first union process (1990 + municipal polygon) was OK.

Then the second union gave me problems.
It seems that union produced duplicated polygons.  I could see that when using transparency.
This map should be equally transparent.

I made two simple fake polygons over the same area and it went well with union.

I've enclosed the shapefiles if anyone is interested in this issue.
---------------------------
Iván Santiago
GIS Specialist
Information Technologies
Office of Management and Budget<https://mail.ogp.gobierno.pr/exchweb/bin/redir.asp?URL=https://mail.ogp.gobierno.pr/exchweb/bin/redir.asp?URL=http://www.ogp.gobierno.pr/>
787.725.9420 x 2378
Calle Cruz 254
PO Box 9023228
San Juan, PR 00902-3228
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