From A to B
Round walk
From and to
Or tap the map to drop A, then B. Once both are down, a tap moves the nearer pin, or drag either one. A pin off the paths joins the nearest one (shown dotted).
Plan route
Place A on the map
Place B on the map
How this works, and what it can't see
Ground and surface heights come from the Environment Agency's 1 m LiDAR composite: the first-return and last-return surface models and the terrain model. Where the laser passed through something it's a tree; where it didn't and the surface is smooth, it's a building or a wall. OpenStreetMap building outlines are always solid.
For every 5 m of path, a ray is traced toward the sun from 1.5 m above the ground. Buildings block it. Tree canopy dims it per metre crossed: heavily in leaf, lightly when bare. Leaf cover follows a UK broadleaf calendar: bare from mid-November to about 10 April, full leaf from mid-May to October.
On roads both pavements are measured: the sunny route assumes you walk on the sunnier side, the shady route the shadier one. The sun moves on as you walk, at 4.9 km/h.
A round walk tries eight directions. Each loop goes out, across and home, and every leg steers off the paths the walk has already used. The loops are ranked on sun (or shade), how close they come to the length you asked for, and how little they double back.
Evening walks count front doors from OpenStreetMap's building outlines: houses, terraces, bungalows and flats, plus untagged buildings of house size, each joined to the street it faces. Streets with homes on both sides score highest; main roads and streets mapped as unlit score lower.
Of the – OpenStreetMap trees in this area, – are tagged evergreen. Every other tree counts as deciduous.
Cloud is ignored: you see the sun you'd get on a clear day.
Hedges, fences and anything built since the LiDAR flight may be missing.
Walks up to 10 km, in England and Wales. In Wales there is no last-return LiDAR, so trees are told from buildings by the map's building outlines only. The first route in a new area takes up to a minute while the data downloads.