dead_reckoning

Like, as in dead reckoning? It's always a sketchy approximation, without a good caliberation, to zero the frame of reference, dead reckoning is guess work, until you hit the next benchmark.

By definition, it's like dunking underwater, and swimming in the dark with your eyes closed. You don't know how accurate your frame of reference is until you reach out to grab a landmark and open your eyes, to recaliberate.