US Patent 10408918 Sky polarization and sun sensor system and method

In a method for determining orientation of an object, raw image data of the sky is recorded using a sky polarimeter. One or more of Stokes parameters (S0, S1, S2), degree of linear polarization (DoLP), and angle of polarization (AoP) are calculated from the image data to produce a set of processed images. Last known position and time data of the object are obtained, and a known Sun azimuth and elevation are calculated using the last known position and time data. Roll and pitch of the object are found, and the roll and pitch data are used to find a zenith in the processed images. The yaw/heading of the object is determined using the difference between a polarization angle at the zenith and a calculated Sun azimuth.