中文摘要：

当用户评估完三维打印模型而需要修改时，目前的编辑技术需要返回原始三维模型进行修改再重新分层，效率低、易出错且编辑不直观．为此，提出面向三维打印的模型编辑方法，即用户直接编辑分层模型的轮廓线，可见即可得，其核心是特征保持的轮廓线编辑技术．首先，将每一条轮廓线分割为特征点和特征段；每个特征点具有特征保持和位移传播的功能，特征保持允许用户自由选择是否保留特征点的角度值，而位移传播则确定了编辑操作的影响范围；两者共同定义了特征点和特征段的编辑模式．然后，根据轮廓线的所有特征及其邻接关系构建一个闭合的特征链图，并结合拉普拉斯坐标的保特征性质让编辑操作在相同层和不同层内的轮廓线上传播．实验结果表明，该方法能够有效地提高面向三维打印的模型编辑效率．

英文摘要：

When a design should be modified after its printed model was evaluated, the current methods needed to edit the original 3D model and to slice again. Thus, this paper proposes a 3D printing oriented editing method, i.e. users directly edit the contours of a layered model, and what you get is what you see. The key idea is a feature-preserved contour editing technique. First of all, feature points and feature curves are detected from each contour; a feature point has abilities of feature-preserve and displacement-transfer; the former allows users to decide whether to keep its angle or not; the latter defines its affecting range; together, they define the editing modes of feature points and feature curves. Then, all features and their neighboring relations in a contour form a closed loop, called feature linked graph. With this graph and Laplacian coordi- nates, an editing operation in one layer can be propagated in the same and neighboring layers. Some ex- periments show that this editing method can improve the editing efficiency for 3D printing models.