dem - Choosing colour-ramp to use for elevation?

This is maybe rather subjective as it concerns style, but I would like to have a few decent colour ramps for my DEM when it is layed over my hill-shading.

I have created the Swiss hillshade model as shown here, but I'm not too convinced that the colour scheme is good.

Any examples or screenshots would be great.

Answer

I usually come at this question from the angle of "what is going to enhance, and not obscure, my data?".

Tufte talks about the some of the uses of colours in maps: to label, to measure, to represent, and to enliven. Choosing DEM colours is usually mostly for the latter (enlivening) - to make them look nice. For example, the default 'atlas coloring' of many maps I see is really pretty (and used in the Swiss hillshade example) - it's derived from something that seems 'natural': white (snow) at the high elevations, green (forests) on the lower slopes, yellow / brown (the plains) and blue (the sea). It looks beautiful, combined with a hillshade.

However, if you apply it everywhere, you end up with map colours that are not representative - they don't reflect reality, and (worse) can be completely misleading. A Luangwa Valley map I produced once made it look like the Alps when in fact it's a deep, hot valley bounded on one side by a cool-ish escarpment (no snow, no large bodies of water anywhere).

Plus, all those colours tend not to photocopy very well, and many offices don't have colour printers where I work, so the colours all disappear or end up becoming just patches of black.

Colorbrewer is great for investigating some of the sequential colour schemes you could use on your maps. You can select 'photocopyable' and other options - but it's kind of depressing how few colours remain as you select more restrictions.

The other problem (measurement) with colour ramps is that the eye interprets divisions between shades where they don't exist – grayscale is far, far better at showing varying quantities (nice essay on this at the visual.ly blog.

So ... I almost always end up using either:

• Grayscale hillshading, or


• A two-colour scheme that represents the ecology or habitat of the area - often from dry (yellow or red) to wet (green).