Fuzzy Overlay (Spatial Analyst)

Available with Spatial Analyst license.

Summary

Combines fuzzy membership raster data together based on selected overlay type.

Learn more about how Fuzzy Overlay works

Usage

• 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.

• See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.

Parameters

Dialog

Label	Explanation	Data Type
Input rasters	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

Python

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"]

# Execute FuzzyMembership
outFzyOverlay = FuzzyOverlay(inRasterList, "GAMMA", 0.9)

# Save the output
outFzyOverlay.save("c:/sapexamples/output/fuzzoverlay")

Environments

Auto Commit, Cell Size, Cell Size Projection Method, Compression, Current Workspace, Extent, Geographic Transformations, Mask, Output CONFIG Keyword, Output Coordinate System, Scratch Workspace, Snap Raster, Tile Size

Licensing information

• Basic: Requires Spatial Analyst
• Standard: Requires Spatial Analyst
• Advanced: Requires Spatial Analyst