A Sectionalized Rotation Method Of Volume And Surface Area Measurement For CT Sequential Images

Industrial CT technology has been widely used in non-destructive testing andevaluation.It is recognized as the best method in non-destructive testing by thenon-destructive testing industry. The three-dimensional image measurement technologybased on the industrial CT system can automatically measure the parameters of theinternal structure of the object and get the three dimensional information online andnondestructively. Current three dimentional measurement methods cannot achieve highaccuracy in edge detection and miss data in the complex contours between layers，whicheventually lead to low accuracy in the three-dimensional parameters and dimensionsmeasurement. Based on the study and improvement of the existing algorithms, thispaper analyzes these problems and further improves the accuracy of measurement of thethree-dimensional.Taken industrial CT image sequences as the research objects in this paper, a newindustrial CT image parameter measurement method for volume and surface area isproposed and adopted.First, slice images are preprocessed. And neighbor tracking the sub-pixel levelcontours which are extracted by the Zernike moments method to get the vectorizedcontour points. Then, the polynomial fitting method is used to fit the contour points.According to the equal phase angle interpolation principle, the contour points in thesame layer are resetted and the ones that belong to the adjacent layers under the samephase angle are matched by the method of cubic spline fitting. At the same time, thecubic spline expressions under subparagraphs intervals are obtained. The top data of theobject is filled automatically by the method of predicting apex. Finally the spline fittingcontours which rotate a fixed phase angle interval is integrated, and each volume andthe surface area of the rotary body is accumulated to obtain the total volume and thesurface area of the object.In this paper, the CT image sequences of actual standard workpieces and thenonstandard ones have been measured three-dimensional volume and surface area. Theresults show that this measurement method has high precision for three-dimensionalvolume and surface area measurement, it is better for applications than the existingmethods, and it also has been further improved in accuracy.