I've got a huge database of depth points for the whole Irish sea which I'd like to be a nice smooth surface, or at least have a depth value associated with the entire area (i.e. include the inter-point spaces). I've tried interpolation but can't get it to work well, so I thought to make Voronoi polygons from the points, and then graduated colour them.
Problem: In 2.1 master, a blank column is created in the Voronoi polygons shapefile, and switching from single symbol: towards graduated results in a complete blank: . This even happens with the csv file, from dots: towards blank: . Andre Joost got around a similar problem by using semicolon delimited files, but it feels to me like this is a genuine bug in master, especially given the same files don't blank the Voronoi shapefile in DuFour: . Has anyone else experienced this? I'm about to raise it on QGis hub.
Question: can I colour the Voronoi polygons using the depth value? The Voronoi shapefile has depth as a field but it doesn't do anything - possibly it doesn't know how to deal with the fact that each Voronoi polygon has a number of depths equal to its number of edges (usually 4 in my case here). Can I colour them using the depth value from the points file somehow?