Terrain height above WGS84 geoid


The source data sets are from https://earthexplorer.usgs.gov/

HGT files (zipped) are available from http://viewfinderpanoramas.org/dem3.html/
XC Guide requires the uppercase file extension '.HGT'

Encoding is defined here http://fileformats.archiveteam.org/wiki/HGT

Each .HGT file consists of a sequence of 16-bit signed integers.
Each value is the elevation of that point above the WGS84 geoid in metres.

The row order is north to south, columns run west to east.

Each file has 1201 rows, each with 1201 columns.

The resolution is 3 arc-second (about 90 metres).

Each file name shows the bottom left lat/long reference of the corner of each tile
e.g. file N50E000.HGT covers N50-N51 x E000-E001 degrees

Files can be reached with the following URL(s)
https://pg-race.aero/agl/N50E000.HGT