Hi all,
For Open/WebGL-based client side map rendering libraries, like MapLibre
or Mapbox GL, Terrain-RGB [1] (original spec by MapBox I believe) seems
to be the elevation encoding of choice.
The encoding itself, meant for use with 8-bits per channel RGB raster
formats such as PNG tiles, is straightforward:
elevation (in meters) = -10000 + 0.1 * (R * 65536 + G * 256 + B)
As far as I know a separate tool is typically used for the encoding,
such as rio-rgbify [2] from Mapbox. There's an example writeup of such
workflow at [3]. Perhaps the same thing could also be achieved using the
raster calculator (gdal_calc), but that seems far from trivial for most
users.
It looks like it would be relatively easy to add native support for this
in GDAL, perhaps as another mode in gdaldem. Would it make sense if I
gave that a try?
- Lars
[1] https://blog.mapbox.com/global-elevation-data-6689f1d0ba65
[2] https://github.com/mapbox/rio-rgbify
[3] https://github.com/syncpoint/terrain-rgb/blob/master/README.md
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