Abstract: Some embodiments include a method and apparatus which obtains sensor data associated with a vehicle. The sensor data includes three-dimensional acceleration data and three-dimensional rotation data, with respect to a sensor coordinate system. A gravity vector is obtained, and it is determined when the vehicle starts moving. Acceleration direction is used as a forward direction of the vehicle. It is determined from the rotation data when the vehicle changes direction, the rotation data indicating two different directions. The gravity vector is used to distinguish which is an upward direction by selecting directions the direction which has larger angle with respect to the gravity vector as the upward direction. The forward direction and upward direction are used to determine a rightward direction. The forward direction, upward direction and rightward direction represent the vehicle coordinate system. The orientation of the apparatus with respect to the orientation of the vehicle is determined.