posts tagged 'dot density'

introducing OpenLayers Symbology

a JavaScript library for thematic mapping in OpenLayers

At last October’s NACIS Practical Cartography Day I gave a very sweaty presentation that was later described as bewildering and incoherent.  I had always meant to partially redeem myself by packaging and cleaning up the code that formed the basis of that talk.  And here it is!
OL-Symbology is [...]

the first thematic maps

Below’s a quick outline of the first maps created with six common cartographic symbologies. All of the below is out there, in books, articles, and blog posts. Particularly helpful are Alan MacEachren’s 1979 article The Evolution of Thematic Cartography, Arthur Robinson’s Early Thematic Mapping in the History of Cartography (1982), Borden Dent’s thematic cartography [...]

hitTestPoint vs. insidePolygon

update: After trying the below method with highly detailed, dynamically stored polygonal data, I now realize that hitTestPoint is MUCH more efficient. Therefore, the below should only be used with very simple (like less than 20 points) polygons. Hopefully it’s still of interest, though!

When creating dynamic Flash dot density maps (see my wiscMapper), [...]