Discontinuous Registration Of Industrial Radiographs Using Profile Analysis And Piecewise Correlation Techniques

Abstract

Two methods are described in this paper for measuring internal machine part clearances by digital processing of industrial radiographs. The first technique requires mathematical modeling of the expected optical density of a radiograph as a function of machine part motion. Part separations are estimated on the basis of individual image scan lines. A final part separation estimate is produced by fitting a polynominal to the individual estimates and correcting for imaging and processing degradations which are simulated using a mathematical model. The second method involves an application of image registration where radiographs are correlated in a piecewise fashion to allow inference of relative motion of machine parts in a time varying series of images. Each image is divided into segments, which are dominated by a small number of features. Segments from one image are cross - correlated with subsequent images to identify machine part motion in image space. Since the magnitude of a correlation peak is a function of the similarity between an image segment and a subsequent image, it can be used to infer the presence of relative motion of features within each image segment thus identifying feature boundaries. Correlation peak magnitude is also used in assessing the confidence that a particular motion has occurred between images. The rigid feature motion of machine parts requires image registration by discontinuous parts in contrast to the continuous image deformations one encounters in projective perspective transformations characteristic of remote sensing applications.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.