[Qgis-user] Differences between polygons (city limit bounds) problem

[Joe Larson]

Hello list!

I've been wrestling with this for a while now - appealing to the 
community for some potential suggestions. I am updating our City Limits 
Boundary polygon for submission to the 2010 Census.

I add the old Census boundary (vintage 1999) polygon and our current 
City Limits boundary polygon to QGIS and run a 'difference' operation 
via fTools, TWICE (2x)...Once gives me the 'IN' pieces and twice gives 
me the 'OUT' pieces. This works great.

I then (try to) perform something like a merge (or maybe dissolve?) with 
the 'IN' poly pieces and then a clip (or maybe another difference 
operation?) with the 'OUT' pieces.

The Census needs two shapefile deliverables: one with all the 'IN & OUT' 
poly pieces and a final polygon boundary. I may have worked on this 
issue unsuccessfully to realize a better strategy - anyone have 
suggestions? let me know if i can elaborate, thx -joe