An area consists of any contiguous clump of cells with non-zero category values. No distinction is made between differing category values within an area. Rather, a border is grown around the outside of each entire contiguous set of non-zero cells.
The output raster map layer will not go outside the boundaries set in the current geographic region. Thus, if a contiguous area in the input raster map layer extends to the geographic edge of the current map layer, no new border cells can be added to that side of the area.
Growth around a rectangular area in the input raster map layer will occur straight out from each edge, but not diagonally from the corners of the rectangle. Thus, the "grown" border area will contain lines along the edge of the original rectangle, but the corners of the border will not be squared off. Instead, the lines of the border which go along each side of the original rectangle will touch only at the corners of the cells at the end of each line.
With -b flag the output will be a binary raster map layer having only zero-one category values, regardless of the category values in the input map layer. In this case, all cells with a non-zero category value in the input map layer are assigned to category 1 in the output map layer. If the -b flag is not used, these cells will retain their original non-zero category values. In either case, all cells whose category value is changed from 0 during the growing process are assigned a category value of 1 in the output map.
If the resolution of the current geographic region does not agree with the resolution of the input raster map layer, unintended resampling of the original raster map layer may occur. The user should be sure that the current geographic region is set properly.
Last changed: $Date: 2003/05/06 13:22:34 $