About SunlightDirection

SunlightDirection shows the direction of sunlight and the shadows cast by buildings, for any city and any time of day.

What it does

Pick a city and drag the time slider to watch shadows move from sunrise to sunset. The map models building shadows using OpenStreetMap building data and the real position of the sun for the chosen date, time and location.

How it works

For every moment, the sun's altitude and azimuth are calculated for the map's coordinates. Each building's height is projected away from the sun to draw its shadow. The lower the sun, the longer the shadow; at solar noon shadows are shortest. It's a model built from public data, so treat it as a close guide rather than a survey-grade measurement.

Data sources

City and place data come from GeoNames. Map tiles and building footprints come from OpenStreetMap contributors. Sun positions are computed with the SunCalc algorithm.

Limitations

Many buildings in OpenStreetMap have no recorded height, so a typical three-storey height is assumed where data is missing. Terrain, trees and overhangs are not modelled. Results are a model, not a measurement.