Complex Region Spatial Smoother (CReSS)

Abstract

Conventional smoothing over complicated coastal and island regions may result in errors across boundaries, due to the use of Euclidean distances to measure interpoint similarity. The new Complex Region Spatial Smoother (CReSS) method presented here uses estimated geodesic distances, model averaging, and a local radial basis function to provide improved smoothing over complex domains. CReSS is compared, via simulation, with recent related smoothing techniques, Thin Plate Splines (TPS), geodesic low rank TPS (GLTPS), and the Soap film smoother (SOAP). The GLTPS method cannot be used in areas with islands and SOAP can be hard to parameterize. CReSS is comparable with, if not better than, all considered methods on a range of simulations. Supplementary materials for this article are available online.

Key Words:

• Geodesic distance
• Local radial basis
• Model averaging
• Thin plate splines

SUPPLEMENTARY MATERIALS

Supplementary tables and figures referenced in Sections 2–4 are available at the web link given. We have also provided code for calculation of geodesic distance, and implementation of the CReSS method on the palm simulation.

ACKNOWLEDGMENTS

The authors gratefully acknowledge NERC for funding and John Harwood for advice.