http://tangrams.github.io/heightmapper

Heightmapper is an interactive grayscale heightmap browser, which can generate heightmaps for use in 3D applications. By default, it "auto-exposes" the display so that the highest visible elevation in the current view will be white, and the lowest will be black.

Uses Mapzen's global elevation service.

• Uncheck "auto-expose" to set min and max height levels manually.
• Click "export" to open the current view as an image in a new tab - "Save As" to save the image to disk.
• Import the resulting image as a "displacement map" in a 3D application to generate a 3D model of the terrain.
• The "z:x scale factor" describes how "high" the current view is, on the z-axis, in terms of how wide the current view is on the x-axis. Multiplying this scale factor by the width of a 3D mesh in units x will tell you how high in units z your mesh should be after displacement in order to be true-scale.
• Press the "h" key to toggle UI visibility.

• add a GeoTIFF export option which includes metadata
• add a toggle to show borders, labels, rivers, etc
• Extra Credit: add an 'export at zoom level' slider, to export at a higher resolution by fetching the appropriate tiles and stitching them together, maybe with a max_width (or max_filesize) parameter so you can export an array of Very Large Files
• Super Extra Credit: further export options including lat/lon bounding boxes, country/boundary masking using OSM vector tiles

Start a web server in the repo's directory:

python -m SimpleHTTPServer 8000

If that doesn't work, try:

python -m http.server 8000

Then navigate to: http://localhost:8000