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Is there a way to interpolate (IDW) while providing clipping geometry? My objective is that I want to interpolate temperature data but I do not want it to interpolate the entire extent of the point file but rather fit the output to the extent of a particular polygon. Thanks.

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2 Answers 2

up vote 3 down vote accepted

go to arctoolbox => 3d analyst tools => IDW => environments => Raster Analysis Setting => Mask

general setting => extent

or

you can use extract by mask tool .extract by mask is not good option to use interpolation.

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I do not think that you can specify a clipping geometry as part of the IDW process, however you can perform a separate clip operation either on your input or your output data and automate this process using python commands.

I would caution that if you clip a subset of the points and then perform an IDW on the subset you will get a different surface than if you perform an IDW and then clip the result to your polygon.

Here are example python commands adapted from the helpfiles for IDW, Clip and Extract by Mask

Clip Before IDW

import arcpy
from arcpy import env
from arcpy.sa import *

env.workspace = "C:/data"
arcpy.Clip_analysis([POINTFIELD], [POLYGON], "studypts.shp")

outIDW = Idw("studypts.shp", "temperature", 2000, 2, RadiusVariable(10, 150000))
outIDW.save("C:/output/idw.tif")

Clip After IDW

import arcpy
from arcpy import env
from arcpy.sa import *

env.workspace = "C:/data"

outIDW = Idw([POINTFIELD], "temperature", 2000, 2, RadiusVariable(10, 150000))
outIDW.save("C:/output/idw")

outExtractByMask = ExtractByMask("C:/output/idw", [POLYGON])
outExtractByMask.save("C:/output/maskextract")
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3  
I am unfamiliar with the latest version of this software, but in all earlier versions (through 9.3), IDW included an option to allow polyline barriers. This prevents it from interpolating across the barriers, which is different than--and more flexible and time consuming than--merely clipping the result of an IDW without barriers. –  whuber Sep 12 '12 at 18:53

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