Elevation Information Extraction Scheme Based on Sub‐Aperture Correlation Using Airborne Circular Synthetic Aperture Radar Imaging

ABSTRACT

Airborne circular synthetic aperture radar (CSAR) enables multiangle observation and high‐resolution imaging, which can extract the elevation information. However, the traditional elevation extraction methods are limited by the low elevation extraction accuracy and complicated processing flow. Thus, an elevation information extraction scheme based on the sub‐aperture correlation using the airborne CSAR imaging is proposed. First, the full‐aperture echo data are divided into multiple sub‐aperture datasets, and then the back‐projection (BP) is used for the sub‐aperture imaging to generate high‐precision sub‐aperture images. Moreover, Otsu‐based adaptive binarisation method is adapted to binarise sub‐aperture images and extract the centroid position of sub‐aperture images, and then the chain correlation calculation is implemented for the centroid position registration of sub‐aperture images. Besides, the geometric relation between the imaging position offsets of targets in different sub‐aperture images are utilised to calculate the line‐of‐sight direction offsets of targets at different viewing angles, and then the target elevation information is derived by solving corresponding relational equations. Finally, the elevation information obtained from all registered sub‐aperture images is fused to generate the more accurate and complete elevation information. Experimental results based on the simulated and measured CSAR data verify the correctness and effectiveness of the proposed elevation information extraction scheme.