Some code for generating topographic contour maps. Documentation is currently lacking, so you're mostly on your own!
cmd/test/main.go will automatically fetch (and locally cache) AWS Terrain tiles and render a topographic isoline map as a PNG. You can specify a lat/lng bounding box or use a shapefile. See the top of main.go to configure this.
cmd/contours/main.go will generate contours for a grayscale input image. Again there are some constants at the top of the file that you can configure.