FieldP-04 · Where, then when
Geolocate and Chronolocate
Place an image in the world and in time using only what is visible in it.
Step 1
Inventory the Fixed Features
Buildings, road geometry, fences, towers, signage, mountain silhouette, vegetation. Fixed means it was there before and after.
Step 2
Establish the Camera’s Direction
Work out which way the lens points from the arrangement of features. Direction converts a field of candidates into a line.
Step 3
Match Against Imagery
Satellite and street-level, and more than one provider — coverage and capture dates differ.
Step 4
Require Convergence
Three or more independent features matching, not one. Publishable geolocation converges; it does not resemble.
Step 5
Read the Shadows
Shadow direction gives the sun’s azimuth; shadow length gives elevation. With a known location and date, a solar calculator narrows the time of capture — or contradicts the claimed one.
Step 6
Corroborate the Weather
Historical weather records for that place and date either support or refute visible conditions.
Step 7
State the Confidence
Say what the geolocation rests on, and how precise it is: this building, or this block.
How It Fails
A confident location built on one ambiguous feature, and a claimed date that the sun angle quietly refutes.