Gets the georeferencing header of an existing flow direction grid.
Header = GetFlowDirGridHeader ( handle_fdr )
integer: handle on the flow direction grid
output, vector containing 7 values: number of columns in the raster, number of lines, cellsize, X coordinate of lower-left pixel, Y coordinate of lower-left pixel, NODATA value, convention for positioning the lower-left pixel.
Gets the georeferencing header of an existing flow direction grid.