Registration algorithms for geophysical maps

Map making surveys conducted underwater, where access to GPS is not available, can incur significant positional inaccuracies. To obtain accurate geophysical maps (e.g. seafloor elevation map, gravity map) for use in high precision navigation, positional inaccuracies need to be corrected by registering overlapping surveys. In this paper, the authors present an algorithm for automatic registration of overlapping data patches. The matching primitives they use in the registration algorithm are contours of constant field value. This makes it possible to apply the algorithm to regions where map features (peaks, ridges, etc.) are scarce. The basic structure of the algorithm is similar to that developed previously by B. Kamgar-Parsi et al. (1989). The new algorithm, however, improves upon the previous technique in several ways, including a new technique for efficient contour matching and a closed-form solution for the optimum transformation. These improvements make the registration more accurate and computationally less intensive. The authors demonstrate the efficacy of the algorithm on synthetic gravity data