摘要
为了重构出相邻齿断面由于密度高度一致,造成在CT图像中丢失的边界轮廓线,先在已提取的牙列整体连续外轮廓上,根据切矢方向的变化,确定出相邻齿廓线的交汇点;再分别以两个相邻交汇点为端点,其间的轮廓点为型值点,构建标准B样条曲线作为部分齿廓线;然后,分别求出相邻齿廓线在交汇点处的一阶导矢,进而求出该交汇点处的平均导矢;最后,以两两相对的交汇点为端点,构建Hermit样条插值曲线,该曲线即作为相邻齿间被丢失的轮廓线。用该方法可以成功地对两颗牙齿进行边界区分,进而提取轮廓,以达到对单颗牙齿进行三维重建,在仿真上能满足临床要求,为后续的牙颌仿真工作奠定了基础。
For reconstructing the contours, which are invisible in CT images due to high identity in the density value, between adjoining teeth, we presented a simple, and feasible method： first, the intersecting points, which were formed by the adjoining contours being parts of outer continuous contour extracted from a tooth-array cross-section in a CT image, were found out according to the saltation of the tangent vector directions on the points. Second, a B-spline, as the representation of a piece of outer contour, was built with two neighboring intersection-points as the end-points, and the outer-contour points as the interpolating points. Third, the one-order derivatives of two adjoining B-splines at common end-point were resolved respectively, and then a mean derivative at the point was computed. Finally, cubic Hermit curves, as the replace of invisible contours between adjoining teeth, were built with a pairs of the opposite intersecting point as end-points. Using this method to determine the edge of the adjoin teeth, and further to reconstruct 3D teeth based on the contours rebuilt with the method mentioned above has proven a satisfying result.
出处
《生物医学工程研究》
2009年第1期28-30,34,共4页
Journal Of Biomedical Engineering Research
基金
国家自然科学基金资助项目(30770559)
山东省教育厅科技攻关项目(J07TJ20)
