Edge effect elimination in the recursive implementation of Gaussian filters

The paper discusses a general methodology to the design of recursive Gaussian filters to be used for separating the form, waviness and roughness components of the surface texture. By selecting appropriate initial values for the filter difference equations, it is possible to eliminate the so-called edge effect and evaluate the whole registered profile. Two ways of filter implementation were considered: series and parallel. The incremental difference operator is applied in place of the usual shift operator z to describe the filter transfer function. This increases the accuracy of the representation of filter parameters and decreases the number of rounding errors. The results of the analysis were illustrated using 2D and 3D roughness profiles of a ball bearing race. The data show that the mean line and the mean surface were correctly determined for the whole area of the measured profile.