[ricksunny]

So I would like to learn more about gravity map matching. I've seen offhand references to it in context of placing an ICBM on target (can't find ref now) but that's it. I imagine it is, (or was for long enough to make info sparse) a classified piece of know-how.

[rcxdude]

For sufficiently accurate IMUs, like the ones found in ICBMs, you need a gravity map because otherwise the variations in gravity cause your position estimate to drift

[ricksunny]

That's helpful; so presumably for the same reason that gyrocompasses function (self-aligning vis-a-vis the local gravity vector).

A part of me was subconsciously entertaining that a subsystem of the IMU / INS was actually being used to provide gravimetric navigation (producing a coarse global position update de novo rather than correct for an error-prone open-loop one from an a priori generated gravity map). a la

https://ieeexplore.ieee.org/document/9059124

or

https://www.researchgate.net/publication/343278497_Analysis_...