ES,I remember reading discussions of this combined method stating that the method could not be made any better than it is now, because the rotation of the Earth is detected by the and fools the system into trying to compensate for it. This causes the system to take the wrong decision because the subject rotates together with the Earth and the camera, so no compensation is actually required. Canceling out the Earth rotation signal in the calculations is not a trivial problem, since it requires both the direction of shooting with respect to the Earth axis and the latitude to be known.
I'm not sure I would buy that discussion, could you provide the reference please?
I have some older experience in this area as about 35 years ago I helped develop the earliest ultra high performance fiber optic gryo concepts based upon the Sagnac effect and patented an electro-optical Serrodyne modulator utllized to linearize the Sagnac effect (Sinusoidal ambiguous & non-linear), and an ultra low noice transimpedance amplifier used to detect the fiber rotating photons. These systems could certainly measure well below earth rate and are used in aircraft, satellite, space probes, missile and precision terrestrial navigation systems. However I don't think these fiber optics based systems have been refined enough to be in our cameras, and suspect the movement sensors in our cameras are simple capacitive MEMs types similar but much more sensitive than the automotive airbag sensors but not able to discern the earths rotational velocity and certainly not relativistic effects.
We must remember than accelerometers measure the time rate of change of velocity, and velocity is the time rate of change of distance which requires a reference position. Since the camera at rest and earth's surface are moving in unison as a reference the time rate of change in relative velocity of the camera is zero unless the camera is moved. Also if the camera is moved at constant velocity the result is also zero.
I don't see how the sensors in our cameras can measure or even respond to the earth's rotation (which is quite constant) since they are simple accelerometers. I admit I haven't delved into this particular gryo/accelerometer subject in a long time, so maybe some progress I'm not aware of has been achieved. If so, please enlighten me.
Best