基于QEM以方差作为权值的3D网格模型简化

为了提高3D网格模型的简化速度和简化效果，采用半边结构表示模型，在拓扑重建过程中使用附加的索引表使拓扑重建时间复杂度由O（nlogn）降低为O（n），在模型简化时，通过计算顶点相邻三角面片法向量的方差来确定顶点的重要度，并将其作为权值加入到Garland的二次误差测度公式QEM中，起到了很好的简化效果。与经典的Garland算法相比采用半边结构能直接获得邻接关系，加快了模型简化速度。在处理边界时对边界情况进行详细分类，既提高了简化速度又保留了模型外观。

Simplification of 3D Mesh Model Based on QEM with Variance as Weights

For enhancing simplification speed and effect of 3D mesh model,adopt half-edge structure to represent the model,and reduce the time complexity of the topology reconstruction from O（nlogn） to O（n） by using an additional index table. By calculating the normal variance of triangular facets connected to a vertex to determine the importance of the vertex, and add it to Quadric Error Metrics （QEM） as weights ,the effect is satisfied. Compared with the classical Garland algorithm the use of half-edge structure can directly gain the adja- cency relation, and accelerate the speed of model simplification. In the processing of model boundary the detailed classifications of the boundary situation not only enhances the simplification speed but also retains the appearance of model.