It looks like he's using vanilla Leaflet and a tile map. Gdaltile My guess is that he used GDAL to color and tile the DEM. GDAL can work with hgt files, but th

It looks like he's using vanilla Leaflet and a tile map. Gdaltile My guess is that he used GDAL to color and tile the DEM. GDAL can work with hgt files, but the DEM he used probably came as a bunch of geotiffs (I haven't checked, but that's pretty standard practice iirc). > Another, even simpler reading help would be sampling the color at the mouse position and displaying a translation into meters. If he's using gdal2tiles to create the tile map, he's likely converting the DEM to an 8 bit raster somewhere in the process, so the information conveyed by each of tiles will be less than ideal. There are ways around this, but they would take some effort, which may be more than what the author wanted to put in.