Sun position (azimuth and elevation) and the shadow cast by a vertical object, for a given place, day and time. Compare with a photo to find out when it was taken: this is chronolocation.

In real life: SunCalc.org, PeakVisor, astronomical ephemerides. Azimuth is measured from north, clockwise (90° = east, 180° = south, 270° = west). A shadow always points away from the sun.