利用牙齿的CT断层图完成了3维实体模型建立。对间隔0.5mm、厚度1mm的每一层断层图像进行二值化、边界提取,并筛选出边界关键点;根据相邻4层边界关键点数据,采用3D-Delaunay四面体化算法,在两层之间生成3维单元实体;根据估算外法线向量与球心顶点向量的内积正负情况对每个单元实体的有效性进行检查;把全部有效实体单元进行3维实体布尔运算,得到牙齿的实体模型。实例证明这种方法简便有效。

The 3D volumetric model of a tooth is constructed based on the image data of CT cross-section layers.Each cross-section image,whose interval is 0.5mm and thickness is 1mm,is treated by two-value conversing,boundary extracting and boundary key points selecting.With the boundary key points of four neighborhood layers,three-dimensional solids between the two adjacent layers are produced according to 3D-Delaunay tetrahedron algorithm.Its validity of each solid element is checked if their internal products between the estimated outward normal vector and the vector from sphere center to vertex are all positive or not.All obtained valid 3D solid elements are combined with Boolean operation,and the volumetric model of a tooth is then achieved at last.This approach is proved to be simple and effective with a tooth sample.