ArcInfo/Arcview grid maps

asciigrid

Asciigrid maps are single ascii files, starting with a number of header lines, followed by the grid cell values (row-wise, from left-to-right). The header lines ave a field name and a value. Field names are pretty much self-explanatory, they are: ncols, nrows, cellsize, xllcenter or xllcorner, yllcenter or yllcorner, and (optional) nodata_value.

floatgrid

A floatgrid map maskmap consist of two files: one ascii file with the name maskmap.hdr that contains the grid map topology (as the asciigrid header), and a binary file named either maskmap.flt or maskmap, containing the cell values. Specify only the file name without the .hdr or .flt extension in gstat commands. Field names in the header file are: ncols, nrows, cellsize, xllcenter or xllcorner, yllcenter or yllcorner, byteorder, and (optional) nodata_value. The field byteorder should have value lsbfirst for byte order of little endian processors (least significant byte first, like INTEL), or else msbfirst (HP-PA and the like).

From version 2.1 on, gstat adds by default the .flt extension to the binary grids file name to facilitate importing in ArcView (with 3D or spatial analyst).