The CAD Model Reconstruction Based On Industrial CT Slicing Data

With the development of manufacturing, Reverse Engineering becomes an important channel of digesting and absorbing the advanced technology overseas. The product can be meaured with Industrial computed tomography (ICT) non-destructively. Constructing 3-D CAD model from slicing data becomes a hot pot in researching Reverse Engineering based on Industrial CT. In this dissertation, some key technologies related to the CAD model reconstruction based on Industrial CT slicing data are studied.Image processing of ICT gray images was firstly accomplished. The coordinate data of contour was got. The Gauss filter and median filter were used to filter the noise, the method of calculating the gray image which was taken as the foundation of segmenting the image to extract the sectional contour was researched, the inner and outer coordinate of contour were got through 8-oriean-tracing.Feature recognition of contour based on curvature was researched. The feature points were got through improved method of"three-Point curvature"and curvature difference, the characteristic of slicing data after image processing was analysed, redundant points were eliminated through calculating the distance, the contour was segmented with the feature points and the type of curve was judged, method of error estimating was used to calculate the coordinate of center point and the radius of arc.The method of data format transforming between contour data after image processing and the CAD software was researched, the data transform programme was developed and IBL, PTS, IGES format file transfomation was accomplished. The IGES file was studied. Both the contour points and contour lines can be expressed with IGES file.The CAD software was adoptd to reconstructing the CAD model in this dissertation. The surface model was reconstructed in Imageware and the entitative model was constructed in Pro/Scantools. The ICT slicing data of teapot was taken as an example, the CAD model was reconstructed in Imageware after image processing and data transforming, the error was analysed. The CAD model can be used in manufacturing and redesigning directly. The validity and feasibility of techniques and algorithms was verified.