The Nearest Neighbor gridding method assigns the value of the nearest point to each grid node. This method is useful when data are already evenly spaced, but need to be converted to a Surfer grid file. Alternatively, in cases where the data are nearly on a grid with only a few missing values, this method is effective for filling in the holes in the data.
Sometimes with nearly complete grids of data, there are areas of missing data that you want to exclude from the grid file. In this case, you can set the Search Ellipse to a value so the areas of no data are assigned the blanking value in the grid file. By setting the search ellipse radii to values less than the distance between data values in your file, the blanking value is assigned at all grid nodes where data values do not exist.
When you use the Nearest Neighbor method to convert regularly spaced XYZ data to a grid file, you can set the grid spacing equal to the spacing between data points in the file. Refer to Producing a Grid File from a Regular Array of XYZ Data for the procedure of converting regularly spaced XYZ data into a Surfer grid file.
In the Grid Data dialog, specify Nearest Neighbor as the Gridding Method and click the Advanced Options button to open the Nearest Neighbor Advanced Options dialog.
Set the search parameters on the General page
in the Nearest Neighbor Advanced Options dialog.
On the General page, set the search range and angle. For more information about search options, see Search.
The Breaklines and Faults page is used to add breaklines and faults to the gridding process.
Producing a Grid File from a Regular Array of XYZ Data
General Gridding Recommendations