I am adding this section early as a convenient placeholder to add diagrams & reasoning to as I develop the feature in v1 of GIS.ly.
Sections
Introduction
Taken from an orienteering technique, handrails are continuous features that you can reliably intersect and then follow to work out where you are or help you get to a destination with less error & effort.
For offsets & just plain noise, GIS.ly v1 will use the handrail orienteering technique as inspiration for correcting a track. The user merely needs to select the start & end vertices, whether the technique is to follow a trough, crest, contour, or most likely viable/possible movement, and the app will attempt to find a route between these two points following the terrain data using the elevation API with some statistical reasoning, calculus, & backtracking techniques.