Synthetic Aperture Sonar Interferogram Filtering by Intensity Image Segmentation

Abstract

Synthetic aperture sonar interferometry relies on the interferogram of two single look complex images to estimate bathymetry. The phase difference measurements have variance, which is typically reduced by spatial smoothing at the cost of horizontal resolution. The high resolution intensity image is related to the bathymetry because of the observation geometry. We therefore suggest an approach that constrains the filtering around edges found by intensity image segmentation. We demonstrate our suggested method on simulated data and show quantitative and qualitative improvements in both the horizontal resolution and the shape resolvability of small objects. We demonstrate a 30% improvement in RMSE of the bathymetric estimate, and observe that the estimated bathymetry more closely renders the real object shape for a small, but elevated object. We demonstrate our suggested method on real data and show similar results.