Why does the Kriging Spatial Analyst tool generate NoData areas in the output raster?

Answer

The Kriging (Spatial Analyst) geoprocessing tool interpolates a raster surface from points using the kriging method. The tool is usually used to create a continuous surface from discrete data points. In some cases, NoData areas are generated in the output raster surface.

The following are possible causes and associated solutions for the NoData areas in an output of the Kriging (Spatial Analyst) tool:

Coincident data points

When more than one point appears at the same location, the Kriging tool is unable to determine the exact point to use for interpolation. Consequently, the output raster presents NoData values in the pixel areas where there are coincident points. The following are possible solutions for this issue:

• Remove all but one data point in the coincident location, and run the Kriging tool.
• If the Geostatistical Analyst extension is available, use the Geostatistical wizard to set the method for handling coincidental sample points.
• Another tool from the Geostatistical Analyst extension that can be used is the Empirical Bayesian Kriging tool, which can handle coincident points.

No data points found in the search radius

The data points within a search radius are used to interpolate the raster surface using the Kriging tool. When there are no data points in the specified search radius of a location, NoData values are generated in the output raster surface. The following are possible solutions for this issue:

• If the Search radius setting is set to Fixed, increase the Distance parameter to ensure at least one data point falls within the search distance, or specify a non-zero minimum number of points, so that when the Kriging tool does not find the required number of points within the specified distance, the search distance are automatically increased until the specified minimum number of points is found.
• If the Search radius setting is Variable, increase the Maximum distance to ensure at least one data point falling within the search distance.

For more information about the Search radius setting, refer to the following web help page, ArcMap: Kriging.

A mask with NoData areas is used in the Processing Extent or Raster Analysis Environments setting

The area with NoData values in the mask is not processed in the Kriging tool, or is masked out in the output raster surface. To check if a mask is used in the Processing Extent and Raster Analysis environment, follow the instruction provided below:

1.  In Kriging tool dialog window, click Environments at the bottom.
2. Expand Processing Extent and Raster Analysis. Remove any unwanted processing extent or raster mask.