A feature extraction method for the assessment of the form parameters of surfaces with localised erosion

An algorithm, referred to as the Defect Removal Method (DRM), is proposed for evaluating the form parameters of surfaces with defects, using three-dimensional (3-D) measurement data. The algorithm excludes data from heavily damaged areas of a surface prior to form fitting using a weighted least squares fit. The nature of the weighting function is varied on the basis of the statistical characteristics of the residuals after form removal. This paper describes the Defect Removal Method and tests it using a range of simulated data sets and a set of measured eroded electrical contact data to look at the improvement on the evaluation of the form parameters of the surface with defects.