I am using QGIS (2.10) to make a growing zone map of the U.S. from some data I found online. I need to reshape to fit into a U.S. map, and I find it's easier if I break the shape into smaller parts, and run an intersect on the smaller part with the map of the U.S. that I have (takes less processing time to do this, then merge the smaller with the larger after). The problem is that it will not let me break the shapefile, because it is an "Invalid Geometry". I have brought it into GRASS and have used v.clean, to no avail.
Is there a function that will actually tell you why the shape is an invalid geometry, or can someone tell me how to purge the invalid geometry demon?
I do not see how to attach a file to this post or I would have attached the shapefile.
