I’m not sure you got me. How do the map makers update the map? If the gravity variance changes so it can’t be used to determine your position then clearly you need some other way to determine your position to update the gravity map. And what might that be??
That doesn’t work too well out in the ocean and lots of other places too. If you can’t use your gravity map, you’re gonna use GPS for precise position data.
I’m not sure you got me. How do the map makers update the map? If the gravity variance changes so it can’t be used to determine your position then clearly you need some other way to determine your position to update the gravity map. And what might that be??
Using the same reference points on earth that GPS uses, that doesn’t mean using GPS.
That doesn’t work too well out in the ocean and lots of other places too. If you can’t use your gravity map, you’re gonna use GPS for precise position data.
Coordinate systems existed before GPS.
Not with GPS accuracy