The Rpm, Rvm, and Rz parameters are evaluated from an average of the heights and depths of a number of extreme peaks and valleys. Rpm the Average Maximum Peak Height, is found by averaging the heights of the ten (10) highest peaks found over the complete 3D image. Rvm, the Average Maximum Valley Depth, is found by averaging the depths of the ten (10) lowest valleys found over the complete 3D image. Rz, the Average Maximum Height of the Surface, is found from Rpm-Rvm. Note that in determining the peaks and valleys, the analysis software eliminates a grid of 11 x 11 pixels around a given peak/valley before searching for the next peak/valley, thus assuring that significantly separated peaks/valleys are found.
Rpm may be useful in establishing the height of the dominant peaked structures which may easily be plastically deformed under contact or penetrate a coating. Rvm provides an estimate of the average valley depths and may be useful in understanding fluid flow through an interface and space for debris entrapment. Rz provides an estimate of the overall peak to valley magnitude of a surface and may serve to predict the thickness of coating needed to completely cover and level a surface.
See also: Average Maximum Peak Height