Three-dimensional filtering of engineering surfaces using envelope system

With the advent of cheap and powerful computers, three-dimensional evaluation of surfaces is possible. This article deals with the development of a computational method for three-dimensional filtering of surface using the envelope system (E-System, a dialation using a sphere) concept. The shape of the envelope surface is dependent only on the prominent peak points on the surface. The computational method developed uses this set of prominent points to facilitate fast evaluation of the envelope surface. Roughness values obtained by two, two-and-a-half, and three-dimensional evaluation of typical surfaces are also given. This procedure of waviness filtering gives a strong base for an integrated approach for surface and form measurements.