Using Contour Lines to Map Density of NYPD’s Stop and Frisk Data

Using Contour Lines to Map Density of NYPD’s Stop and Frisk Data | MapBox
▻http://www.mapbox.com/blog/contour-lines-density-mapping

Next we convert the raster heat map into vector contours using the gdal_contour option available in #qgis under the raster / extraction menu.

http://farm9.staticflickr.com/8012/7563181614_492f207b50_z.jpg

#heatmap #gdal