Hi all, This may be a wishlist/ plugin thing, but is there a way have a layer render or not depending on how many features there are in the frame? So if there are 100 points in the frame the layer renders, but if there are 101 the layer is invisible?
My use case is this: I look at census tracts overlaid on aerial imagery (a lot), panning and zooming and identifying to verify population attributes. In urban dense areas, the tracts are really small (because the census aims for more or less constant population), but in rural areas they can cover an entire county. I use scale dependent rendering, but I have to change it all the time depending on what I am looking at. About a dozen tracts is usually the perfect amount to look at in a frame. It would be easier to write an algorithm for points than polys, but maybe it is an interesting enough problem someone (hehe) should implement a naive approach and see if it works. I can imagine there being problems when the frame has both high and low density pieces (is non-homogeneous), but maybe it would work anyway. I can also imagine that chaining several layers together so that they switch on and off depending on the density might be useful. You could use hierarchical geographies (e.g. blocks, block groups, tracts, counties, states), but also more abstract features too. I have absolutely no idea how to implement this, but I would be happy to try/ report bugs/ whatever. Thanks for the attention! _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user