SPATIAL REPLACE TOOL Input: a thematic (categorical) raster layer Output: a new raster layer Features:
replaces cell values in a raster layer by assigning the closest permitted alternative value
provides a method of removing unwanted categories from a raster layer by
assigning new values based on a simple neighborhood analysis, rather than a
works on any size/shape of patch in the raster (i.e. works equally well for
linear classes like roads, pipelines or rivers as it does for large patches
like cutblocks, agricultural fields, etc)
allows the user to interactively define the set of acceptable replacement values
processes only one band of the raster
replaces only one value at a time (to replace multiple values, the tool
would have to be run once per value)
[Click for larger view]
Figures A, B & C. In this example two values in
the original raster (A) are replaced. Those two values represent roads (bright red
cells in A) and cutblocks (orange cells in A). Because the tool replaces one
value at a time, it has to be run twice to accomplish this. Th first time the
tool is run, roads are replaced by any other non-water feature (B). The second time
it is run, cutblocks are replaced by any other forest type (we know that if it
was cut it had to be forested at one time, therefore it would not make sense to
allow cutblock cells to be replaced with Grassland or Water values). The final
result is shown in C.
A raster layer must be loaded into ArcMap in order to use this
tool. If you wish to run this tool on a multi-band image, you must load
the bands into ArcMap separately, and run the tool on each one.
Priority of replacement values.
This tool begins by examining the 8 cells immediately surrounding the cell
that is being spatially recoded. If there are any acceptable replacement values
among these 8 cells, it will select the lowest value (even if another higher value is in
majority). If there are no suitable replacement values in these 8 cells, the tool moves
out by one cell, and so on, until an acceptable replacement is found.