Rotation volume measurement method based on CT sequence images

According to the common engineering workpiece with dramatic axial contour changes, a high-accuracy inter slice contour rotating integral volume measuring algorithm of Zernike moment sub-pixel edge detection is presented. Firstly, a sub-pixel level contour is detected by Zernike moment method. Secondly, using the polynomial fitting method the contour is fitted, and then the fitted contour is sampled by the same angle interval. Each edge point at the same phase angle of each slice is used to fit the contour, and then the apex of work-piece is calculated through extrapolation method. Finally, each fitted contour is rotated through one phase angle interval to calculate the integral as a rotation volume, the volume of each rotation is accumulated to be the total volume of the workpiece. Volumetric measurement experiments are carried out towards three volume-equal testing workpieces. The results indicate that the measurement errors are less than 0.7% using the proposed method. An actual work-piece with internal cavity is measured. The result indicates that the measurement accuracy of the proposed method is 1.5 times than the one of the Canny-frustum method.