DESCRIPTION is an Bourne Shell and Awk script. It is an interface between the external nnbathy utility and GRASS. nnbathy is a surface interpolation program provided with nn - a natural neighbor interpolation library, written by Pavel Sakov. provides 3 interpolation algorithms. According to nn library documentation these are: Delaunay interpolation (alg=l), Watson's algortithm for Sibson natural neighbor interpolation (alg=nn) and Belikov and Semenov's algorithm for non-Sibsonian natural neighbor interpolation (alg=ns). For performing the underlaying Delaunay triangulation in all cases nnbathy uses triangle software by Jonathan Richard Shewchuk.

The output raster map is a continous surface interpolated from the input raster map.

nnbathy, if built with '-DNN_SERIAL' (default as of nn 1.85), is able to create a grid of virtually any size. It interpolates and writes one output point at a time only. This eliminates the necessity to hold the whole output array in memory. However, even then all the input cells are still held in the memory.




Maciej Sieczka

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