This tool is recommended for use with the result of the Fuzzy Membership tool. It is meant to be applied to rasters with values that range between 0 and 1.
The following are the appropriate Overlay type parameter values to use for certain conditions:
Use Or to get the maximum value from all of the input evidence rasters. If any of the inputs have a high value, the final output will be high.
Use And to get the minimum value from all of the input evidence rasters. All inputs must have a high value for the output to be a high value.
Use Product when the combined evidence is less important than any single evidence.
Use Sum when the combined evidence is more important than any single evidence.
Use Gamma to combine more basic data. When gamma is 1, the result is the same as Sum. When it is 0, the result is the same as Product. Values between 0 and 1 allow you to combine evidence to produce results between the two extremes established by And or Or.
A list of input membership rasters that will be combined in the overlay.
Raster Layer
Overlay type
(Optional)
Specifies the method that will be used to combine two or more membership data.
And—The minimum of the fuzzy memberships from the input fuzzy rasters will be used.
Or—The maximum of the fuzzy memberships from the input rasters will be used.
Product—A decrease function will be used. Use this when the combination of multiple evidence is less important or smaller than any of the inputs alone.
Sum—An increase function will be used. Use this when the combination of multiple evidence is more important or larger than any of the inputs alone.
Gamma—The algebraic product of the Sum and Product options, both raised to the power of gamma, will be used.
String
Gamma
(Optional)
The gamma value that will be used. This parameter is only available when the Overlay type parameter is set to Gamma.
The default value is 0.9.
Double
Return value
Label
Explanation
Data type
Output raster
The output raster that is the result of applying the fuzzy operator.
This output will always have a value between 0 and 1.
Raster
FuzzyOverlay(in_rasters, {overlay_type}, {gamma})
Name
Explanation
Data type
in_rasters[in_raster,...]
A list of input membership rasters that will be combined in the overlay.
Raster Layer
overlay_type
(Optional)
Specifies the method that will be used to combine two or more membership data.
AND—The minimum of the fuzzy memberships from the input fuzzy rasters will be used.
OR—The maximum of the fuzzy memberships from the input rasters will be used.
PRODUCT—A decrease function will be used. Use this when the combination of multiple evidence is less important or smaller than any of the inputs alone.
SUM—An increase function will be used. Use this when the combination of multiple evidence is more important or larger than any of the inputs alone.
GAMMA—The algebraic product of the SUM and PRODUCT options, both raised to the power of gamma, will be used.
String
gamma
(Optional)
The gamma value that will be used. This parameter is only available when the overlay_type parameter is set to GAMMA.
The default value is 0.9.
Double
Return value
Name
Explanation
Data type
out_raster
The output raster that is the result of applying the fuzzy operator.
This output will always have a value between 0 and 1.
Raster
Code sample
FuzzyOverlay example 1 (Python window)
This example combines the input membership rasters with the And overlay type to identify the minium membership value between them.
import arcpy
from arcpy.sa import *
from arcpy import env
env.workspace = "c:/sapyexamples/data"
outFzyOverlay = FuzzyOverlay(["fzymembout1", "fzymembout2"], "AND")
outFzyOverlay.save("c:/sapexamples/output/fuzzover.tif")
FuzzyOverlay example 2 (stand-alone script)
This example combines the input membership rasters with the Gamma overlay type.
# Name: FuzzyOverlay_Ex_02.py
# Description: Combine fuzzy membership rasters data together based on
# selected overlay type ("GAMMA" in this case).
# Requirements: Spatial Analyst extension
# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *
# Set environment settings
env.workspace = "C:/sapyexamples/data"
# Set local variables
inRasterList = ["fzymembout1", "fzymembout2"]
# Run FuzzyMembership
outFzyOverlay = FuzzyOverlay(inRasterList, "GAMMA", 0.9)
# Save the output
outFzyOverlay.save("c:/sapexamples/output/fuzzoverlay")