From and to
Or tap the map to drop A, then B. Drag either pin to move it.
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.
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 5 km, in England. The first route in a new area takes up to a minute while the data downloads.