Nondestructive Testing of the State of Surfaces Damaged by Corrosion Pitting

Abstract

We study the problem of three-dimensional reconstruction of the surface on the basis of its two-dimensional images with an aim to apply the results of its solution for the analysis of the images of materials damaged by pitting. We propose a method for finding the depth of pitting according to the estimates of a series of metallographic images with the help of the Lambertian model of reflection of light. We determine the parameters of the model by analyzing the changes in the location of a source of light with the use of additional shading, and the invariable location of the receiver. The series of analyzed images contains a triple of images, obtained for different directions of illumination and also the shaded image of pitting. We describe a two-step algorithm aimed at the estimation of the characteristics of pitting on the surface of the material according to its images. In particular, we show that the use of the proposed methods enables one to obtain information about pittings. We also present an example of practical application of the developed algorithm for the 3D reconstruction of the surface of actual pitting.