Assessing the 3D Parameter S_a 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 S_a, which is very commonly used in investigating surface microrelief. It is an analog of the familiar parameter R_a and therefore extensively used in practice. Increased requirements on the surface quality of products call for the development of 3D microgeometric parameters.