Much of the early work to develop standard, worldwide 3D surface measurement parameters was completed by a European consortium. Their work resulted in four general categories: amplitude, spatial, hybrid and functional.
The amplitude parameters are based on overall heights and include the root-mean-square of height distribution, skewness (or the degree of asymmetry of a surface height distribution), the degree of peakedness of a surface height distribution (or kurtosis), and an average of the highest and lowest points.
Spatial parameters are based on frequencies of features and include the texture direction of a surface, texture aspect ratio, and the density of summits.
Based on a combination of height and frequency, the hybrid parameters include the mean summit curvature, developed surface area ratios, and the root-mean-square of surface slopes.
Finally, the functional parameters include several parameters that are based on applicability of particular functions.