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I have a set of data points in a CSV format. I want to create a contour map using the data points so I used IDW Interpolation in ArcGIS. But, when I checked the maximum value of the output raster, it was different from the maximum value of data points. Did I miss something when I used the IDW Interpolation or should I use another interpolation method (Krigging, natural value, etc)?

The Excel data points The output raster properties The IDW Interpolation settings

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A spline interpolation will compel your surface to pass through the sample points.

See here, and here for some information on different interpolation methods.

Since these interpolation methods are 'making up' data between your points the best interpolation method may depend upon the distribution of your points and the type of land you are trying to interpolate (tide flats or canyons?). Of course, you would not know which surface was 'better' unless you had some control data and did a further analysis. Search GIS SE for root square mean error if you want to try to determine the best interpolation surface from your points.

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  • Hi, Thank You very much for the information. I have read the website and I thought the spline method would be the right choice. But, after I tried to use it, there are some problems that I want to ask: 1. It still didn't give the maximum value 2. It gave a negative value (I know it was due to the method using derivatives). Is there any correlation between the number of data points to the output? my data has roughly 250,000 points btw.
    – Hafidz
    Apr 19, 2023 at 13:14

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