Sketch-based Mesh Segmentation And Editing

In digital geometry processing, how to conveniently and efficiently edit triangle mesh models has always been a subject that researchers and animation designers pay attention to. Similar to the role that image segmentation plays in image analysis and understanding, mesh segmentation is one of the most important operations in geometric modeling and processing and has a lot of applications in computer graphics applications such as texture synthesis, shape analysis, recognition and matching, shape modeling and morphing.In computer graphics community, several approaches have been proposed for automatic mesh segmentation. However, the automatic segmentation may not be what the user needs for a specific operation such as editing certain part, morphing, and modeling, thus an interactive method should be considered in a certain situation. We propose an interactive algorithm on part-type segmentation, which helps users extract meaningful parts from mesh models. When we get foreground and background seed faces from the sketch curves that users draw, scalar values are assigned for each seed face separately. Then we obtain scalar values for all faces of the mesh by solving a sparse linear system. The values can form a scalar field. In this field, we can trace an isoline with a scalar value resulting from k-means clustering. The isoline is an initial cutting boundary, which can be further refined and modified.On the basis of mesh segmentation algorithm, we design a system to do geometry processing for 3D meshes. In this system we implement the functions of mesh deforming, merging and morphing. In the flow of mesh deforming, users set reference and target sketch curves to control the deforming part. Then we get the gradient field of the deforming part. By solving a Poisson equation we can get the deformed poses. The merging operation mainly includes loading the models, segmenting models, Setting key vertices, merging parts, smoothing connecting areas and so on. After mesh merging, we can do morphing operation to the cutting parts so that more result poses are formed.As geodesic distance is not necessary to be calculated, our segmentation method is fast and can be widely used. It can segment both single models and sequence models. The experiment results show that mesh editing operations based on segmentation has an easy way for users to interact, and is efficient in time and space. Moreover, we can obtain different result meshes with good quality.