Image Registration and Mosaicing of Acoustic Camera Images

This paper presents an algorithm for image registration and mosaicing on underwater sonar image sequences characterized by a high noise level, inhomogeneous illumination and low frame rate. Imaging geometry of acoustic cameras is significantly different from that of pinhole cameras. For a planar surface viewed through a pinhole camera undergoing translational and rotational motion, registration can be obtained via a projective transformation. We show that, under the same condition, an affine transformation is a good approximation for an acoustic camera. We further propose a novel image fusion method, which maximizes the signalto-noise ratio of the mosaic image. The full procedure includes illumination correction, feature based transformation estimation, and image fusion for mosaicing.