Give a person a single street-view photo with no metadata and ask them which country it is. A trained GeoGuessr player will often get it in a few seconds. They are not reading a hidden GPS tag. They are reading the image: the color of the road lines, the shape of the bollards, the script on a distant sign, the vegetation, the direction of the sun, the style of the power poles.
I spent a long time building a system that does the same thing from one frame, and the interesting part is how ordinary the core idea turns out to be. Here is what actually matters, and what does not.
The problem, stated honestly
Single-image geolocation is: given one photo, output a location. In practice you want two things at once, and they are not the same task.
Coarse: which country or region is this. This is a classification problem over a few hundred buckets.
