ArcGIS Tutorial: Weighted Overlay

　　Summary

Overlay multiple raster data using frequently measured proportions and assign weights based on the importance of each raster data.

　　Illustrations

　　

In the illustration, two input rasters have been classified again as 1 to 33 common measurement levels. Each raster is assigned an impact percentage. These cell values are multiplied by their effect percentages, and the resulting results are added together to create the output raster. Take the upper left cell as an example.

The values of these two inputs change to (2 * 0.75) = 1.5 with (3 * 0.25) = 0.75. 1.5 and 0.75 of the and for 2.25.

Since the output raster obtained by the weighted overlay is an integer, finally the value is rounded to 2.

　　How to use

· All input raster data must be of integer type.

Floating-point raster data is first converted to integer raster data, and then the ability is used in the weighted overlay.

The reclassify tool is an effective way to run a swap.

· Assigns a new value to each value class in the input raster based on the rating level. These new values are reclassified to the original input raster values.

Restricted values will be used for areas to be excluded from the analysis.

· It is weighted according to the importance or percentage of influence of each input raster data.

Weights are relative percentages, and the sum of the influence percent weights must be equal to 100.

· The result of weighted overlay analysis can be changed by changing the rating or impact percentage.

　　Code instance

　　Weightedoverlay Demo Sample 1 (Python form)

The suitability IMG raster created by this demo sample can identify the location that can be used as a ski area.

Import arcpy

From arcpy Import env

From ARCPY.SA Import *

Env.workspace = "C:/sapyexamples/data"

Outsuit = Weightedoverlay (Wotable (

[

["Snow", "$", "VALUE", Remapvalue ([[1, "NoData"],[5,3],[9,10],["NoData", "NoData"]]),

["Land", "Remapvalue", "'", "[[" Water "," 1 "],[" Forest ", 5],[" open field ", 9],[" NoData "," NoData "])],

["Soil", +, ' VALUE ', Remapvalue ([[1, "Restricted"],[5,5],[7,7],[9,9],["NODATA", "Restricted"]])]

],[1,9,1]))

Outsuit.save ("C:/sapyexamples/output/outsuit.img")

　　Weightedoverlay Demo Sample 2 (stand-alone script)

The suitability IMG raster created by this demo sample can identify the location that can be used as a ski area.

# Name:WeightedOverlay_Ex_02.py

# description:overlays Several rasters using a common scale and weighing

# Each according to its importance.

# 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

InRaster1 = "Snow"

InRaster2 = "Land"

InRaster3 = "Soil"

Remapsnow = Remapvalue ([[0,1],[1,1],[5,5],[9,9],["NoData", "NoData"]])

Remapland = Remapvalue ([[1,1],[5,5],[6,6],[7,7],[8,8],[9,9],["NODATA", "Restricted"]])

Remapsoil = Remapvalue ([[0,1],[1,1],[5,5],[6,6],[7,7],[8,8],[9,9],["NoData", "NoData"]])

mywotable = Wotable ([[InRaster1, +, "VALUE", Remapsnow],

[InRaster2, "VALUE", Remapland],

[InRaster3, Max, "VALUE", Remapsoil]

], [1, 9, 1])

# Check out the ArcGIS Spatial Analyst extension License

arcpy. Checkoutextension ("Spatial")

# Execute Weightedoverlay

Outweightedoverlay = Weightedoverlay (mywotable)

# Save the output

Outweightedoverlay.save ("C:/sapyexamples/output/weightover2")

ArcGIS Tutorial: Weighted Overlay