Highlight steep segments on the elevation chart

[oliverlockwood]

Our elevation chart currently looks like the screenshot below. There were a number of brutal 25% segments both in the ascent and descent of the first pass I did this morning, which it might have been nice to know more about beforehand 😆

My idea is to introduce highlighting, something like:

• yellow for >=5%
• orange for >=10%
• red for >=15%
• black for >=20%

I haven't yet dug into examples of the data, but probably, achieving this would involve applying a rolling filter on the distance/elevation data arrays, and requiring something like a minimum of 25m distance averaging any of the above gradients for the colouring to be applied, so we don't have artefacts of data-rounding errors making 2m segments being highlighted.

[mvl22]

The main thing is to make it a quarter of that height. It makes a moderate rise look like a mountain currently.

[oliverlockwood]

It is a mountain... If not technically according to the definition of being at least 610m high.

If you've never ridden north over the pass from Eskrigg and then back over (le Col du) Buttertubs, I recommend giving it a go and then re-evaluating your view 😉

[oliverlockwood]

More seriously, the problem is that ratios of route length and altitude change vary immensely, so automatically choosing bounds and scales is non-trivial. I believe the way it's currently set up is pretty good, but if you have feedback that could be applied to all routes in general and not just one, please raise that as a separate issue. I believe it is orthogonal to this enhancement proposal.