| Industrial Computerized Tomography technology is using ray to acquire the data with transmitting the dislocation of objuects to be test with the scan way under the objects undamaged, then to get the sequence of workpiece's dislocation image using the computer special image reconstructive algorithm, the workpiece's dislocation images provide surface structure and internal structural integrity's information. Industrial CT technology is non-destructive measurement, and has high measurement accuracy, so in reverse engineering, parameter measurement of internal parts and other fields has broad application prospects. In this paper, the application of the Industrial CT images'edge processing skills in the reverse engineering and measurement is researched. The main research contents and contribution in the thesis are as follows:Firstly, the characteristics of Industrial CT images are analyzed and the images are enhansced and denoised. Next, the images'edge processing algorithm based on Industrial CT images are studied, such as edge detection, edge tracking. In many edge detection algorithms, the edge detection algorithm based on Facet model is emphasisly researched. Because it makes full use of information of the adjacent points, and has anti-noise ability, higher accuracy, so Facet model is used for the Industrial CT images edge detection. Last, edges of the images in each workpieces edge image are tracked out with Freeman list method; they are getting ready for the following reserve fitting and the measurement of the internal workpiece's parameters.According to the known information, the data of each Industrial CT images edge is fitted to the cylinder, elliptical cylinder or a common three-dimensional surface plane. For the fitting of the cylinder and elliptical cylinder, firstly, the center points of outline edge on each Industrial CT edge images are acquired and are fitted to the central axis through these center points, the projection data is acquired by the cylinder data projected to the cross-section perpendicular to the central axis. Finally, the least-squares algorithm is used for fitting a round or oval of the cydlinder section perpendicular to the central axis, that is, the acquirtion of various geometric parameters of the cylindrical or elliptical cylinder is completed. Fitting to other surfaces, corresponding surface fitting algorithms are used; these geometric parameters were used to generate CAD drawings, so this method lays the foundation for reverse engineering based on Iindustrial CT images. VC + + 6.0 was applied to realize the above-mentioned methods and practical Industrial CT images experiment, results show that the method can accurately measure the geometric parameters of the workpiece.Methods for wall thickness and roundness error measurements of workpieces based on Industrial CT images are studied. Firstly, Facet model is used for the Industrial CT images edge detection. Next, both inside and outside edge of the wall in the workpieces edge image are tracked out with Freeman list method, the similar round edge of workpiece is also tracked out, then the distances between each points in the inside wall list and the outside wall list are calculated. Finally, the wall thickness can be calculated by calculating the average of the distances, the least region method is applied in the measurement of the roundness error. VC + + 6.0 is applied to realize the above-mentioned methods and practical Industrial CT images experiment, the results on the simulation and the actual Industrial CT images show that these methods could accurately acquire wall thickness and roundness error of the workpieces in the Industrial CT images. These methods are particularly suitable for the cross-section wall thickness measurement of closed inner cavity and the roundness error measurement of inner annular in the work pieces. They could play an important role in the quality control of manufacturing, and also could be used in the measurement of geometry parameters in inverse manufacturing. |
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