I added contour lines (map here) to my IDW map (read here). The map has contour breaks at 25, 50, and 75. I was really flying by the seat of my pants coming up with this algorithm – it’s pretty computationally intensive, but it does run (at least on Firefox), so don’t panic if the “This script is non-responsive” pop-up pops up. If there’s any demand for it, I’ll write up an explanation of what’s going on, but until then you’ll have to figure it out from the source code (good luck). And, if you’ve got a more streamlined raster to contour routine, I’d love to hear about it!
This is my second fear mongering post seemingly focused on 10,000km-range North Korean missiles (the first can be found here). I’m really not all that concerned about North Korean missiles in my day-to-day life. The real point of this post is that the web map (here) features animated SVG symbols that are (that is, appear to be) animated along circles, not simple polylines (they actually are polylines in the shape of geodesic circles). Also, notice that the “symbols” are in fact numbers, not simple shapes, which took a while to code, so I hope you enjoy them.