Good to see you are working on this and taking the analyses results so seriously!Īs you requested I tested this in arcgis. But this obviously must be discussed in the dev mailing list. I would be in favor to eventually remove (temporarily) the tool from qgis 2 and reinstate it later when a solution is found. I'm still convinced that we cannot ship a tool that we know produce a wrong result. I believe that in this case the operations are made by unioning/intesecting the layers 2 by 2 and then the result unioned/intersected with the following one.īut the current solution is worse than mine, although both are "wrong". There is already a feature request to allow choose >2 input layers (as for example Arcgis does). (***)In QGIS union and intersect just allow to select 2 input layers. The result of a union operation is just one layer, so in the example you are using all the resulting 11 features are in the same layer, a few of them repeated/overlapped. In the example the circles would be in one layer and the rectangle in another. This is the common situation, the union tool needs two inputs. What is expected if the two circles resides in one layer and the rectangle resides in another layer? I guess that eventually the same layer can be used two times, but I don't think it makes much sense. I don't know if I understand correctly, but as far as I know, the union operation is supposed to have 2 (or more***) different inputs. Is it the expected behavior if the three geometries are inside the same layer, right?