Seafloor Slope Estimation and its Theoretical Accuracy in Interferometric Synthetic Aperture Sonar

Estimating the seafloor slope from interferometric synthetic aperture sonar (SAS) measurements is useful for many applications. The fundamental approach to estimating the slope in a gridded depth map is straightforward, but its statistical accuracy is also desired. We provide expressions for the slope, incidence angle, and normal vector estimates. Then, we derive the Cramér-Rao lower bounds (CRLBs) of these estimates based on error propagation from the CRLBs of the depth estimates. Simulated SAS data supports our results by approaching the theoretical CRLB, and real data examples demonstrate that our results are applicable in practice.