When gridding a data set with numerous duplicate data points using the Modified Shepard's gridding method, sometimes the resulting grid contains unrealistic Z values that are far extrapolated from the z range in the data file (for example, values in the -268420 to 227897 range compared to a range of 3400 to 6600 in the data file). When this happens, the best solution is to apply a data filter during gridding. To do so:
- In the Grid Data - Select Data dialog, click the Filter Data button.
- Change the To Keep value in the Duplicate Data section to anything other than All.
- Click OK.
Now you can proceed with setting the other gridding options as desired to create your grid, and the result should have a more appropriate z range.
Updated October 2021