[GRASS-dev] [grass-code I][452] v.overlay misses some vector elemnts with "and" operator

[grass-dev at grass.itc.it]

code I item #452, was opened at 2007-08-05 21:36
Status: Open
Priority: 3
Submitted By: Andras Fabian (alpilotx)
Assigned to: Nobody (None)
Summary: v.overlay misses some vector elemnts with "and" operator 
Issue type: other bug
Issue status: None
GRASS version: CVS HEAD
GRASS component: vector
Operating system: Linux
Operating system version: SUSE Linus 10.2 / Kernel 2.6.21 
GRASS CVS checkout date, if applies (YYMMDD): 070804


Initial Comment:
I have noticed a new issue with v.overlay and the "and" operator, although I don't know, if this is in some way related to "[#384] v.overlay with 'and' operator sometimes produces wrong results" http://wald.intevation.org/tracker/index.php?func=detail&aid=384&group_id=21&atid=204
(which was added to the tracker Maciej Sieczka in my name - though nothing happened on that bug, why ???)
OK, this time it looks like this. I have a set of vectory polygons (call it "polygons_select") and one larger vector polygon which almost overlaps the previous ones (call it "eco_clipped_central_appalachian"). Now, I would like to cut A by B, so I obviously do a v.overlay with "and". Or as it looks in reality: "
v.overlay ainput=polygons_select atype=area alayer=1 binput=eco_clipped_central_appalachian btype=area blayer=1 output=polygons_current operator=and olayer=1,0,0 --overwrite
"
Now the resulting "polygons_current" is missing some polygons, which should obviously NOT be missing! See attached screenshots:
- polygons_select.jpg is where I start 
- polygons_select_WITH_eco_clipped_central_appalachian.jpg shows the second polygon (in transparent yellow) which I would like to overlay with the first ones.
- polygons_current.jpg shows with the red arrow, where one polygon is missing.

I also attach the vector sets from GRASS, so maybe someone could test it out. As I'm working on a slightly time critical project, it would be very helpful to have some response within the next weeks. Thank you very much!

Andras Fabian

http://www.alpilotx.de (where many infos about my project can be seen)


 

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You can respond by visiting: 
http://wald.intevation.org/tracker/?func=detail&atid=204&aid=452&group_id=21