Can you elaborate?
GPS can be faulty in cities.
Pokémon Go scans, are primarily in cities.
The mapping in the article, is specifically saying to use visual cues when GPS is faulty.
How is this not directly 1-1 overlapping, the gap and the solution.
However that data has a half life and needs to be refreshed.
For flying drones, ground level data is really not that useful. mainly because you can't see it, because its obscured by trees, building and clouds.
But, this is not a new thing. Google, Apple, facebook and niantic all have VPSs as do a bunch of other startups.
For Drones you will probably need SLAM to capture the map, and then once you have the initial map, you can keep it updated.
You can experiment at home using https://github.com/colmap
Like you see in drone races. But with a little bomb attached.
Even with half life. That could be years. Depending on changes. Old neighborhoods probably haven't changed.. And, not sure I read that deal had a cutoff, or not. Could they continue getting updates. ?
The issue you have there is you need a high shutter speed with no rolling shutter to get good reading.