Aggregation of digital terrain data using a modified fractal interpolation scheme

A modified fractal interpolation scheme that can be used to produce consistent digital terrain models at different spatial resolutions is introduced in this paper. The focus of the paper is on the aggregation of fine resolution terrain data to coarser scales (up-scaling), although the algorithm is equally useful for disaggregation purposes (down-scaling). Applications with digital elevation models (DEMs) for California and for Pennsylvania are used to illustrate the methodology. Comparisons with alternative approaches such as sampling of fine resolution DEMs, the use of mean and envelope orography representations, and the Cressman-type objective analysis are presented. The modified fractal interpolation scheme preserves well both the spatial structure of the elevations and orographic gradients and performed consistently better than other algorithms, especially for high level aggregation (coarse discretization).