针对目前颅面相似度评估主要依靠主观验证、缺乏衡量相似度的物理量等问题,提出一种3维颅面几何相似度评估方法。将颅面相似度评估看做是待比较颅面到数据库中其余颅面的弯曲变形,计算出待比较颅面的Principal Warps作为新的基,给出颅面间对应全局特征点的选择方法,并利用薄板样条函数建立映射,从而计算出相应的弯曲变形矩阵,将该矩阵表示为基与系数矩阵的乘积。实现了在待比较颅面固定的情况下,用系数矩阵来衡量颅面间的变形程度,并在此基础上定义了颅面间几何相似度距离,给出了具体比较方法。实验结果验证了该方法的有效性。

An approach of 3D craniofacial geometry shape similarity estimation is proposed to solve the problem that current approaches mainly rely on subjective assessment for the lack of related quantities. In our approach the cranioface, which is to be compared, is transformed into another one in the database and its principal warps are computed to be the base for the representation of the shape change. First, the global landmarks are selected from the two craniofaces and the thin-plate spline function is used to establish a map between them. Then, the corresponding bending transformation matrix is computed. This matrix can be represented by the product of the principal warps and one coefficient matrix, which is used to measure the deformation degree of the craniofaces. Finally, the geometry similarity distance is defined on the basis of the coefficient matrix. Experimental results demonstrate the feasibility and effectiveness of the approach.