elevation-profile

Simple elevation profile Web service similar to google's elevation Web service.

Demo installation using freeDEM data:

• get elevation for some points (latitude, longitude) separated by "|" and return simple JSON

  http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=sjs

• upsample path with a maximum distance of 100m and return a SVG plot of the profile:

  http://karme.de/elevation-profile/demo?path=48.5,9|48.5,9.1&upsample=100&format=svg

• fetch 20 samples along the path and return a SVG plot of the profile:

  http://karme.de/elevation-profile/demo?path=48.5,9|48.5,9.1&samples=20&format=svg

• js

  JSON output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=js

• sjs

  JSON output (simple format) http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=sjs

• xml

  XML output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=xml

• sxml

  SXML output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=sxml

• sexpr

  S-expression output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=sexpr

• svg

  SVG output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=svg

• geojson

  GeoJSON output http://karme.de/elevation-profile/demo?locations=48.5,9|48.5,9.1&format=geojson

• free software / open source
• stacking of multiple DEMs (it is really simple to add another DEM dataset if the format is supported by gdal)
• upsample polyline (keeping original input points and inserting equidistant additional points if needed)
• wgs84 spheroid distance calculations

git repository at: https://karme.de/git/elevation-profile

file releases at: https://karme.de/elevation-profile/files/

If http overhead is a problem you might wish to use the elevation-profile tool providing a simple command line interface. You can use it either directly via pipes or in combination with systemd socket activation or good old inetd, xinetd or socat. For systemd and xinetd example configurations are included and installed by default. The default configuration binds to 127.0.0.1 only. If you want to limit access to a specific user on localhost you can try using ident and hosts.allow/deny (unfortunately the lua socket library doesn't support unix domain sockets, otherwise I would change the default config to unix domain sockets). The lua client example in lua/ uses socat.

Using apache2 I observed problems using mpm_event and I suggest to use mpm_prefork for now:

a2dismod mpm_event ; a2enmod mpm_prefork