Hi all, hi Carson, Needing to sum some pollutants concentrations stored in a polygon shapefile, I come across a big problem with the "join attributes by location" of the ftools plugin. My source polygon shapefile is for simplification a regular grid, and the target shapefile too, with exactly the same limits (in fact the source shp is based on the target on). When calling the plugin, it first complains about source and target are in differents CRS, which is false (I use EPSG 27572), and after computation using the "sum summary of interesting features", the results are somewhat unexpected, because in each target polygon, the sum represents the sum of the contigous sources polygons, and not just the sources polygons INSIDE the target one. To be clear you can see in the attached file an example where the sources concentrations values are in normal font (one value by polygon), and in bold the resulting sum in the targets polygons (where normally expecting the same values as in the sources). I think there's missing a test in the plugin to select values if they are strictly inside the target. Hope there's a simple solution, I really need the values :/ Thanks PS : without this problem, the ftools plugin is really a nice tool. Good job Carson :)
-- Lionel Roubeyrie chargé d'études LIMAIR - La Surveillance de l'Air en Limousin http://www.limair.asso.fr
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