High resolution, consistent navigation and 3D optical reconstructions from AUVs using magnetic compasses and pressure-based depth sensors

Benthic imaging AUVs can deliver down-looking imagery with consistent altitude and illumination. These images are well suited to image matching routines that form the basis for mosaicking, vision-based Simultaneous Localisation and Mapping (SLAM) and 3D visual reconstructions. We show how these same visual constraints can be used to (1) improve the real time dead-reckoning accuracy of AUVs equipped with magnetic compasses and (2) to quantify the accuracy of various corrections applied to measured pressure to determine vehicle depth. We present results from full coverage optical imaging surveys conducted in the field by our AUV to illustrate the impact of these refinements on the ability of the vehicle to successfully complete its missions and the quality of the resulting seafloor models.