The Surgtool program inputs SMOKE-formatted gridding surrogates for a “fine” input grid and a grid definition for a “coarse” output grid. It produces an approximate “coarse” grid surrogates file, the accuracy of which depends on how fine the resolution of the input grid is relative to that of the output grid.

The program requires that the input and output grids use a lat-lon, Lambert Conformal, or UTM map projection. Surgtool can also perform Lambert-to-Lambert and UTM zone-to-zone transformations. In addition, the program requires that the input grid resolution be much finer than the output grid resolution (at least three times finer is recommended, though no specific limitation is given by the code). Surgtool supports SMOKE-formatted surrogate coefficient files only.

Since Surgtool is an optional program that creates new Area and/or Mobile BGPRO spatial surrogate files from existing Area, Mobile and/or Biogenic BGPRO spatial surrogate files, it must be run before any of the following programs that use these files: Grdmat, and Smkmerge.