extrapolation

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10-25-2017 04:08 AM
AMALBOUZIANE
New Contributor III

hi every one,I'm trying to extrapolation my spatial data to larger area, but I don't know if its possible and which tool can.

I m working with pollution concentrations ,its follow a specific spatial trend 

thanks

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XanderBakker
Esri Esteemed Contributor

Can you elaborate a little more on what type of data you have, the current extent of the data and how far you would like to extrapolate the data? Also do you have acces to the Geostatistical Analyst extension?

AMALBOUZIANE
New Contributor III

yes I have access to Geostatistical analysit extension,I have pollutant concentration of an area and I  apply the EBK Regression Prediction method  from Geostatistical wizard in  Arcgis PRO using altitude raster as prediction variables.for the area i got very pretty result but I wanna to extrapolate for larger area.

the current extent of the data

top :50.856194

bottom:50.767833

left:15.151972

right:15.357413 dd

and I like to extrapolate to

top :51

bottom:50.7

left:15.10

right:15.4

please note that I tried the extent tool but it s not activated in arcgis pro

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DanPatterson_Retired
MVP Esteemed Contributor

Set your analysis extent to the larger extent prior to running the tool.  In any event, extrapolation is generally a bad idea unless you are absolutely sure that trends seen at the edges persist beyond the margins

AMALBOUZIANE
New Contributor III

Yes I m sure that there is a trend it been demonstrate by prior studies in the field.

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XanderBakker
Esri Esteemed Contributor

Just remember that it is a relatively large area that need to be covered by extrapolation. Without some additional information, like a trend or something that would enable Co-Kriging, your result will not be very accurate 

AMALBOUZIANE
New Contributor III

thanks for your answer,but I how can I do the extrapolation which tool I must use

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XanderBakker
Esri Esteemed Contributor

So, technically you can use extrapolate your data to a larger extent, as long as you follow the instructions provided by Dan (set the desired extent for your output in the Geoprocessing Environment). Which tool can you use? Probably any interpolation tool available in Spatial Analyst/3D Analyst and Geostatistical Analyst. Since you have Geostatistical Analyst, this is the preferred tool for the job. If you have any other information that has coverage for the entire area and there is a strong relationship between this data and your pollutant concentration, you would use this relation in Creating a prediction map using cokriging—Help | ArcGIS Desktop  to create your map. Geostatistical Analyst is also preferred since it will create a probability map that will tell you more about the quality of your result. Expect lower quality the further you are from the area covered by your data.

Also have a look at: What are the different kriging models?—Help | ArcGIS Desktop 

AMALBOUZIANE
New Contributor III

great thanks

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AMALBOUZIANE
New Contributor III

yes I m trying to extent this to larger area but I coudnt do it in arcgis pro like I use to do in arcmap

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