Periodic Extension of Grid‐Based Data

ABSTRACT In contexts such as mineral prospecting based on gravitational and magnetic surveys, common pre‐processing steps bring the data to equispaced two‐dimensional (2D) grid locations. The region with data is often of a highly irregular shape and may contain internal voids. Given the power of Fourier‐based data processing, a key task becomes to extend such data to become periodic over a larger 2D rectangular region, in a way that artefacts caused by the extension process become minimized. We describe here a new and computationally fast numerical technique for this task. Numerical illustrations include magnetic recordings from the McFaulds Lake area (Ontario, Canada).