Tracks statistics

The gain is an important value that helps to appreciate the overall profile of a track. A small gain means that the track is mostly flat, a high gain means you'll have to climb a lot.

Strictly speaking,

• The gain is the sum of all positive altitude differences along the track;
• The loss is the sum of all negative altitude differences along the track.

In order to compute these values, it's important to define more precisely what means “along the track”.

A first definition would be to take into account the differences between mountain passes and summits. If you start a hike at +150m, climb to a summit at +500m, then go back to your start location at +150m, your gain will be 350m. In practice, trails usually don't go straight forward to the summit, but will go uphill for some time, then downhill a little bit, then uphill again, etc. This first definition doesn't take all these small changes into account, and will then lead to an under-estimated gain.