The Thresholding Utility dialog is used to clip the surface heights that extend above or below specific threshold values.  The two sliders on the legend gradient can be dragged up and down to specify the upper and lower threshold values.  In the example below, the threshold levels were set so that a detailed analysis of the "pile up" material surrounding a microhardness dent could be examined in more detail.  The sample points that are outside of the threshold region can either be set to the threshold values or can be marked as non-measured values.