Assessing the 3D Parameter Sa of a Digital Surface Model

An algorithm is proposed for determining the roughness according to the digital model of a 3D surface in accordance with State Standard GOST R ISO 25178-2–2014 (Geometric product specifications, GPS). The parameter considered is the arithmetical mean height of a scale-limited microrelief surface Sa, which is very commonly used in investigating surface microrelief. It is an analog of the familiar parameter Ra and therefore extensively used in practice. Increased requirements on the surface quality of products call for the development of 3D microgeometric parameters.