Confocal Ellipse Hough Transform for Polarization Compass in the Nonideal Atmosphere
Jue Wang, Pengwei Hu, Jianqiang Qian, Lei Guo
Abstract
The polarization compass is an autonomous, long-endurance compass technique that is intended for enhancing the environmental suitability of the integrated navigation systems. Numerous research on polarization compass is based on the single Rayleigh scattering model. However, the real atmosphere is usually non-ideal and does not conform to the ideal single Rayleigh scattering model. The single Rayleigh scattering model would have a constant error in a non-ideal sky with a certain partial cover. Compared with the single-scattering model, Hannay’s model with multi-scattering equations provides a better description of the polarization pattern in the real atmosphere. Thus, the ellipse Hough transform algorithm(EHT) is proposed in this study to extract neutral points from the polarization pattern based on Hannay’s model to correct the error mentioned above. To prove the effectiveness of ellipse Hough transform algorithm, several experiments have been carried out in the non-ideal sky. And experiment results show that the average error of solar zenith and azimuth angle of the Hough transform is less than 1° in non-ideal weather with 30% cover. In conclusion, the ellipse Hough transform improves the accuracy of the polarization compass by 50% in multi-scattering light with a partial coverage of the sky and enlarges the environmental suitability of the polarization compass.