Dear list, A function in the intamap package currently uses the bivariate interpolation method for irregularly spaced data from the akima package. This dependency is a problem because of license mismatch (intamap is GPL >=2, akima has an exclusively non-commercial license). Does anyone know about a good alternative to this method? The method must be able to interpolate from an irregularly spaced observation network to a grid, and the interpolated surface must be smooth, i.e., differentiable. The method should ideally be fast also for larger data sets. The thin plate splines regression in the fields package (Tps) seems to produce a smooth surface, but struggles with memory consumption when the observation network is large (>2000 points). mba.surf in the MBA package is very fast, but it could run into problems with heterogeneous sampling patterns. Any other suggestions? Is there a natural neighbor interpolation method implemented in R? Best wishes, Jon
Jon Olav Sk?ien Joint Research Centre - European Commission Institute for Environment and Sustainability (IES) Land Resource Management Unit Via Fermi 2749, TP 440, I-21027 Ispra (VA), ITALY Disclaimer: Views expressed in this email are those of the individual and do not necessarily represent official views of the European Commission.