Thursday, 30 July 2015

Showing elevation and slope on a map for cycling

A while ago, I was thinking about making a map that showed elevation and slope by colour-coding. It is often conventional to show elevation with contours, or by some sort of arbitrary colour palette.

Slope is shown on a map usually by contours being closely spaced, or by arrows shown along roads in some cases. Contours can sometimes obscure map features in some cases.

An alternative approach I have used to produce, is to colour-code both elevation and slope simultaneously in different colour channels.

In the cases below, I have used the blue band for elevation, and red for slope. Since I intended this as a map for cycling I have named the different scalings after professional cyclists.

Elevation shading colour codes elevations from 0-150m above sea level in the blue channel, and slope values from 0-10 degrees (up to 22.5%) in red. This map is optimised for lowland areas, however at higher elevations the direction of elevation change is no longer clearly shown on this map.
Elevation shading colour codes elevations from 50-400m above sea level in the blue channel, optimising the map to show elevations in the higher part of the range. Slope values are shaded from 0-10 degrees (up to 22.5%) in the red channel as earlier.

I give a few more examples of this using a different slope scaling and downloads of larger image files on my website.


  1. If you don't mind the asking .... How did you obtain the road slope gradient in the end ? Or is this slope for the land itself ? (In geomorphons maybe?)

  2. This is still just the slope, not the slope along the road. I keep meaning to work on that, but then I also want to do a bit more on the Cornish language processing stuff, and I do want to get back to Mars as well soon.