[Tagging] Planning route in the shade during hikes either in urban areas or forests

[bkil]

Okay, let me try to slowly answer the raised issues.

> The presence of shade or not is a possible mitigation for several hazards.  I think about 2 very distinct hazards: heat and sunlight. Heat is an issue for most people, sunlight not necessary, as people with darker skin are not necessarily bothered by excessive sunlight.
>

In the most recent decades, you can get skin cancer from sunlight, and
it also causes general skin aging. Even an hour of sunbathing can be
damaging around here.


> Excessive sunlight, thus the absence or presence of shade can also be a hazard in cold climates during winter, in regard to snow blindness.
>

I think considering reflections from the snow would be quite a
challenge and I think should be out of scope of finding shade.


> Heat can extend to the periods when a surface is shaded, think about an asphalt road which has overheated and keeps heating the direct air above long time after the period it was exposed to direct sunlight. A serious hazard, even for pedestrians or hikers with darker skin or drivers without airco.
>

This will bother pets as well, as already mentioned. However, it does
not sound viable to map this, but suggestions are welcome.

> So instead of inventing some kind of a shade tag I would go for hazard=heat and hazard=sunlight.
>

Interesting idea, but in such cases, it would be useful to see where:

- shade has not been surveyed yet
- where shade can be found to a certain level (thus the absence of sunlight)

How do you mark a path as shady to differentiate it from those paths
that you have not surveyed, hazard:sunlight=no? This sounds a bit
involved.


> Further defining or quantifying the hazards with severity and frequency (like seasonal tag, periods of a day) and eventually a threshold (like average air temperature) can provide just sufficient data to allow decision making by a user and make the tag viable for a long period, having climate change in mind.
>

Average air temperature 1 meter above the ground per every path sounds
like something that most people won't be able to measure, verify or
even approximate. However, it could be inferred from verifiable tags
like surface=* and the exact 3D geometry of the surrounding foliage,
whether the plants are regularly watered and/or the
summer_midday_shade=* tag.

> Hazard can be applied on ways but also more detailed on areas, thus you can use it for larger areas with varying shade or heat exposure due to absence of shade. Specifying hazards like heat and sunlight will also make this data interesting for use with other applications like sun blinding in evening periods, planning of buildings, buffer zones, sun screens, camping spots, etc... .