Sunrise/sunset maps based on terrain obscuration

Martin M shared this idea 16 months ago
Collecting votes

In summer or winter, having sun or not makes a huge difference for many activities, particularly in the mountains. Climbing, cross country-skiing, camping might be much more/less fun/safe depending on when the sun comes in. I once wanted to go climbing in winter on a south facing crag (Lidernen area, central Switzerland) but had to find out that the terrain was sloped in the wrong direction and at that time the climbing sector would never get sun.

So the idea is: Based on date/time, calculate a map (overlay) that shows where there is sun at that time and where a mountain is still in it's way. This requires some basic ray tracing and a good enough terrain model. I don't know if the SRTM data is sufficient, but mm resolution LIDAR data gets availble progressively so it is just a matter of time until each mole hill is mapped. Most people will have DEM data downloaded already for hill shading, so this should not be a big thing!

Instead of a black/white map overlay, it could also be false color indicating the time of sunrise/sunset for a specific location.

Regards, Martin

Replies (4)


This seems really helpful!

Also a little complicated though.

So maybe start with a useful feature that might be easier to implement for a start:

Add the ability for some kind of compass overlay, which can be placed on the map and show the angles of sunrise/sunset/etc.

see also:


Very nice idea. I think it's more cartographers then developers work, but maybe Locus team is going to make some clever feature.


Right now this feature would be very useful. Last Saturday we rode up the Furka pass (2429). We were in the sun most of the time, but after we reached the pass, the sun vanished quickly and it got freezing cold. So an answer I'd like is to: When do we have to start up the Grimsel pass in order to have a decent amount of sun?


Here's a QGIS plugin that might do that:

Main idea there is to visualize terrain more clearly, but one of the four presented algorithms might do what I'm looking for. I guess I'll have to fire up QGIS to see if it does.

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