I second Nicolas' IDW suggestion though since a point source signal strength is proportional to the inverse square distance you might want to take that into account
On Sat, Jun 19, 2021, 10:57 Nicolas Cadieux <[email protected]> wrote: > Hi, > There are multiple ways of doing this. The Join attributes by location > (Summary) could help you could the number of polygons overlapping the > point. You could then split the overlapping circles into smaller parts > and then use the join by location again to transfer the sums polygon of the > points back to the various circle parts. Then use the symbology by > classification using this field. > > A much better way would be to make an interpolation of your point data > instead. The easy way would be just to make a heat map. The best way would > probably be to use IDW with a search radius. The gdal version of idw found > in processing will permit you to do this. Find an interpolation method > that is compatible with the phenomenon you are studying. For example IDW > is would be better that a tin or a voronoï polygon. > > Nicolas Cadieux > https://gitlab.com/njacadieux > > Le 19 juin 2021 à 10:54, Richard Duivenvoorde <[email protected]> a > écrit : > > > > Hi List, > > I'm experimenting to create 'flower'-shaped polygons for a point layer, > denoting the signal coverage of several directional radio transmitters on a > pole (fyi: to find/locate bats with small transmitters). > > After some fiddling I came to the attached result for a point with 3 (but > dynamic from attribute) transmitters using the following expression: > > collect_geometries( > array_foreach( string_to_array("azimuths"), > make_circle( make_point( > $x + "bereik_m"/2 * cos(radians(@element)), > $y + "bereik_m"/2* sin(radians(@element))), "bereik_m" ) > )) > > The result being a multipolygon with overlapping parts. > > In this work the overlapping area'a are (apparently) the most interesting, > as there the 'location' accuracy is highest. > > So my question: is there a way to give the overlapping area's really > different colors. > I've been playing with the layer rendering options, but ideally the area's > in which there is no, 2 parts, 3 parts, and 4 parts overlapping should be > differently colored.. > > I could try to create more advanced expressions (or probably I would go > for some python) for that, but I was hoping maybe there is another > trick/idea to use current multi-polygons, without adding 'parts' > > Any help/tip is appreciated. > > Regards & TIA, > > Richard Duivenvoorde > <multipolygon.jpeg> > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >
_______________________________________________ Qgis-user mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
