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Comment by crubier | Hacker News Reader

Aerospace grade laser gyroscopes are incredibly expensive (and bulky), and even then, they still have massive drift after several hours. If you don't have GPS to relocalize precisely at least every day, there is no way you can know the location of the camera on earth for more than a day, even with state of the art aerospace stuff

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> they still have massive drift after several hours. If you don't have GPS to relocalize precisely at least every day

I think you may be confusing two concepts: Measurement of true north and latitude via gyro (what the GP is talking about) and inertial navigation systems (which, yes, do drift).

You can measure those two things with just a single-axis gyro and no external references using a technique called "gyro-compassing". In fact, most internal navigation systems use gyro-compassing to directly measure true north and latitude to align the system on initial startup.

Realistically GPS is the answer, but it’s notable that you could also use a simple light sensor combined with accurate clocks to get your position on earth:

https://en.m.wikipedia.org/wiki/Light_level_geolocator

> Recording light levels over time Wonder how much time is needed to determine location.

You just need to determine the time of sunrise and sunset relative to a known location and you get a rough idea of latitude and longitude.

But the location of the camera doesn't matter. You only need to figure out very roughly at which latitude you are to know by how much to compensate for earth rotation. And you can do that with the sensors that you're already using to do the stabilisation. That was my point... no need for GPS.

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