OpenStreetMap

Trees!

Posted by SomeoneElse on 14 June 2015 in English (English)

As you may be aware, mapping of areas of trees in OSM is complicated. It's not possible to tell just by looking at the data which of the four(!) approaches described on that page someone is using "natural=wood" and/or "landuse=forest" to mean. It therefore didn't make a lot of sense to me to display them differently on a map created from OSM data.

Last year there was a proposal to record "leaf_type" and "leaf_cycle" separately, which makes sense (though the wider range of non-European tree types doesn't seem to be catered for as well as previously. Unfortunately a previous version of that page suggested that "wood=deciduous" should be replaced by "leaf_type=broadleaved", and a no doubt well-meaning non-local mapper decided to change some areas of mainly deciduous woodland to "leaf_type". Whilst some of these were correct, clearly there are some issues with this, but as I was changing some that I did have local knowledge of, the thing that mainly struck me was that the situation on the ground was far more complicated than previously mapped, or rendered, on OpenStreetMap. I therefore decided to start trying to record "leaf_type" and (when there was enough data, render it. Initial results can be seen here: Trees in Clipstone That location corresponds to here in OSM. There's a lot more to do there, but at least there's a bit more detail than "a large area of trees".

That rendering is created by a combination of this lua script at osm2pgsql data import time and this stylesheet. It's primarily designed for showing England-and-Wales-specific rights of way, but trees seemed like a natural extension.

Comment from Warin61 on 14 June 2015 at 23:49

You say "Remote mappers will be able to map geometrics of buildings, roads and land use with the help of aerial imagery. "

I find remote mapping land use is not precise. And orchard looks much like a vineyard ... a group of buildings could be a village ... or a collection of farm buildings ... There can be a lot of assumptions made .. best to leave things off the map if uncertain?

I take a cautious approach to remote mapping roads. I prefer to down grade a road classification rather than make an assumption that upgrades it ... possibly beyond its' actual class.

Remote mapping buildings .. I don't usually map those. I'll map them where they are unusual (shape) or a long way from anywhere else. But there it typically much to map, so I concentrate on the roads, large villages, towns. The rest ... local knowledge should be used.

Comment from Warin61 on 14 June 2015 at 23:51

Opps .. wrong entry .. sorry. I make no comment on your trees problem.

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