Skylight polarization patterns under urban obscurations and a navigation method adapted to urban environments

Abstract

Owing to preferable anti-interference and anti-cumulative-error capabilities, polarized skylight navigation technology has been developed. However, in urban environments with extensive demand, the sky is usually partially obscured by buildings and trees. Urban landscape obscurations with polarization patterns that have not been sufficiently studied can greatly influence navigation accuracy. In this paper, we study the polarization patterns generated by obscurations and summarize the impacts of obscured urban sky scenes on the navigation results. We also propose a full-sky polarization imaging navigation method adapted to urban environments. A compact full-sky polarimeter is established, and a specific pattern inpainting algorithm based on convolution operation is proposed to amend the navigation errors caused by obscurations. Among 174 sets of comparative experiments, 90.2% of the extraction results are improved after inpainting, which verifies the effectiveness and robustness of the method. Discussions on the optimization of parameters in the algorithm and the recommended values are also provided. This work offers a novel approach to overcome the impacts of obscurations for urban polarization navigation.