2011/1/30 John Smith <deltafoxtrot...@gmail.com>: > On 30 January 2011 21:05, M∡rtin Koppenhoefer <dieterdre...@gmail.com> wrote: >> broken by design... >> There won't be an "invalid polygon", there would be 2 valid but >> contradicting polygons. > > Which are sorted by smallest first usually so they render on top of > the larger ones.
This is a method of trying to extract useful data from an undefined state making assumptions, but it is IMHO not how we should design our data model. This would also mean that even with complete data for the whole world, you would need endless processing if you wanted to estimate the area covered by sand: for every area tagged surface=sand you would only know it's real extension after subtracting all other polygons with different surface-values (or with an assumed different surface). You also seem to reduce this to a rendering problem. There can also be cases where a bigger polygon overlaps for a small part a smaller polygon. cheers, Martin _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
