Calculate altitude with mixture of barometer and rangefinder

[ClayMav]

Since the rangefinder reports the most accurate altitude, but its relative to the thing closest to the bottom of the drone, it will be inaccurate when hovering over obstacles. Find a clever way to decide when to use the rangefinder vs the barometer.

[ClayMav]

One strategy would be to check if altitude and barometer are within a small range of each other (basically the error of the barometer) then use the rangefinder, else use the barometer for altitude.