The Study Of NURBS-Based 3D Teech Reconstruction Algorithm

NURBS are widely used in CAD/CAM and graphics. Introducing of the weight provides larger flexibility for design and control of the shape, so as to can conveniently represent the shape which various users required, it has a broad application in the field of shaped mould design.The purpose of this paper is using the related principle of the NURBS curve and surface to reconstruct 3D tooth surface under the circumstance of the discrete data with the certain array rule.Firstly, a series of study and deduction of NURBS character are done. The invariant weight of cubic Bezier curve and cubic B-spline curve and the expression of matrix of cubic NURBS are deduced. The calculation method of reverse NURBS node vector is improved.Secondly, NURBS is used to reconstruct 3D tooth surface. That have mainly steps as followed: pretreat the image of tooth CT, extract the tooth contour and obtain the discrete data; compress and reduce the obtained discrete data; calculate the node vector, reverse calculate control points and its weight; on the premise of the invariant contour curve shape, do the NURBS subdivision, increase the number of control point, make each of the slice data equal; structure the uniform nodevectors with the U and V direction, carry through 3D surface reconstruction of the tooth. Result show that it has a great flexibility on reconstruction of tooth.