Objectives
- Establish a location by convergence of fixed features
- Use shadows and weather to test a claimed time
Lesson
Geolocation is a matching problem with a standard of proof. Start by inventorying the fixed features — rooflines, road geometry, poles, fences, signage, terrain, mature vegetation. Fixed means it was there before the image and after it.
Then establish which way the camera points, because direction turns a field of candidate places into a line through them.
Match against satellite and street-level imagery, and use more than one provider: coverage and capture dates differ, and the building you need may exist in only one of them. The standard is convergence. Several independent features matching in the same geometry is a geolocation; one distinctive-looking building is a resemblance.
Chronolocation uses the sun. Shadow direction gives the sun's azimuth and shadow length gives its elevation, and both are strict functions of place, date and time.
With the location fixed, a solar calculator will narrow the capture window — or contradict the claimed one. When the shadows are impossible for the stated place and hour, you have learned that at least one of place, date and time is wrong, not which.
Corroborate with historical weather records for that place and date, then publish what the match rests on and how precise it is. “This building” is a different claim from “this block,” and the reader is entitled to know which one you are making.
Faculty
Bellingcat
Stichting Bellingcat
Open source verification, geolocation, chronolocation, published methodology
Taught as published method: the techniques and the editorial standard, including the requirement that outside readers can reproduce the work. Specific investigations are referenced only as demonstrations of technique.
Reproducible method is the claim being taught. Any particular investigation's conclusions are that organization's, not this site's.