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I would like to split a shapefile in qgis according to how the polygons overlaps.

See pic for explanation:

enter image description here

gisnside
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kogia
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3 Answers3

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I think I found a method. It s a grass function included inside the sextante plugin. See the screenshot. I did a test with a shapefile that looked like yours.pic

More Details:

  1. It is best to install QGIS Sextante Plugin. So you do not have to worry about importing/exporting to grass datasets.

  2. The tool is Located in Sextante toolbox > Grass Commands > Vector > v.overlay

  3. Just open the tool and use the default parameters and you get the results in a new layer

enter image description here

vinayan
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Shepherdjo
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I am more familiar with ArcGIS than QGIS but I just did a brief search and think this would work:

1) Use the Union tool (as suggested by Darren Cope) to create your 7 features.
2) Under Data Management Tools use "Join attributes by location" and take the sum of the number of your original (purple in your map) polygons that overlap your new 7 features.

Thus where there is only 1 original poly, the new field = 1, where there are 2 polys, field = 2 and so on.

AlmaThom
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    Here is a good site with info on the QGIS equivalent of a Spatial Join: http://maps.cga.harvard.edu/qgis/wkshop/join_spatial.php – AlmaThom Aug 01 '12 at 22:25
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The standard QGIS Georeferencing tool "Union" will give the same result.

Darren Cope
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  • i can't get it working as per the asker's requirement..i gave input and union layers the same..are you sure it would work? – vinayan Aug 01 '12 at 16:23