Use of morphological closing filters for three-dimensional filtering of engineering surfaces

Morphological closing filters have been suggested in the literature for processing of profile and functional characterization. In the present work, an attempt is made to extend it to three-dimensional surfaces. Though a sphere is a logical extension of a circular structuring element, a doubly curved (toroidal) element is considered for establishing a reference surface representing waviness and form errors. By such an element, different filtering characteristics in the x and y-directions can be obtained. In this paper, transmission characteristics of morphological filters are presented first for theoretical surfaces. The reference surfaces are also obtained for the practical surfaces and further analyzed by random process techniques.