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Axes: Latitude [decimal degrees], longitude [decimal degrees], altitude [metres]
Increasing altitude is moving away from centre of the Earth
Origin: Equator, IERS reference meridian (IRM) (prime meridian), mean sea level
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Axes (Euclidean): North [metres], east [metres], down [metres]
Positive Increasing value of down is moving towards centre of the Earth, negative is away
Origin (usually takeoff point): Latitude of home position, longitude of home position, altitude of home position (e.g. the ground)
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