SRTM data is distributed at horizontal resolution of 30 meters for areas within the U.S.A. and at 90 meters resolution for the rest of the world. A resolution of 90m can be considered suitable for small or mediumscale analysis, but it is too coarse for more detailed purposes. One alternative is to interpolate the SRTM data at a finer resolution; it won't increase the level of detail of the original DEM, but it will lead to a surface where there is coherence of angular properties (i.e., slope, aspect) between neighbouring pixels, an important characteristic when dealing with terrain analysis. This work intents to show how the proper adjustment of variogram and kriging parameters, namely the nugget effect and the maximum distance within which values are used in interpolation, can be set to achieve quality results on resampling SRTM data from 3arcsec to 1arcsec. Examples are presented for two areas in southeastern Brazil.
C. H. Grohmann, S. S. Steiner