Your GPS can be faked.
Four other witnesses can't.

WHAMI never trusts a single sensor. It cross-examines GPS against magnetic field, inertial motion, sky geometry, barometric altitude and visible landmarks — then scores how many of them actually agree. Watch what happens when the GPS starts lying.

What you're seeing. The pink GPS dot walks away from the truth. WHAMI's blue dot doesn't follow it — because motion, sky and landmark witnesses all still agree with each other. GPS gets down-weighted to near zero, the trust score collapses, and the fix holds on the remaining evidence.