Interactive Approach For Easy Mesh Modeling

Three-dimensional geometric modeling and processing is an important research topic in computer-aided design, computer graphics and computer animation. It has been widely used in various applications including computer games, medical visualization, entertainment industry, simulation, computer-aided manufacturing, architecture and so on. The efficiency, flexibility, and the quality of the modeling method are the primary challenges. The previous geometric modeling systems generally require much professional skills and efforts from the user to model complex and high-quality 3D models. On the other hand, a large number of 3D models have been created in recent years with the fast development of 3D data acquisition technologies. It appears that a compound approach using decomposing, merging, editing, and optimization would become useful and powerful in a modeling tool. In this paper, we have studied on the interactive approach for easy 3D modeling and developed a series of simple and efficient modeling algorithms. Our contributions are summarized as follows.1. Based on sketching mesh decomposing, an interactive mesh cutting tool is proposed, which is an intuitive and easy-to-use mesh cutout tool. Users can cut meaningful components from meshes instantly by simply drawing freehand sketches to roughly specify which parts of the mesh are wanted or unwanted. Sketch-based interfaces offer a natural method of interaction with computer applications because they mimic traditional expression on paper using pencils. The segmentation is based on the minima rule in human cognitive vision theory, which solves the problem on decomposing meshes into meaningful components interactively. Based on an improved region growing algorithm, instant visual feedback can be provided for users. Combined with the Poisson merging approach, it reuses existing models efficiently. It presents its importance in practical to improve the reusability of models and the efficiency of the three-dimensional modeling, and to reduce the difficulty of 3D modeling.2. A unified sketch-based mesh decomposing and editing approach is proposed. On one hand, the sketch-based interfaces are simple and natural for mesh editing; on the other hand, the sketches using to decompose the model are reused to guide the deformation, because they can be considered as a model of "gesture" information. Combined with Laplacian mesh editing, our method can preserve details of the source mesh. In addi- tion, considering the similarity between the sketch and the one-dimensional skeleton, we proposed a sketch-base mesh editing method combined with the skeleton. Prong feature points correspond to tips of the branches of the shape are detected, then the skeleton is computed with the assistance of prong features. A novel representation—skeleton and balls are constructed simultaneously, which gives a solution to combining the skeleton and sketching. This representation is simple but preserves the topological structure of the object, and provides a more flexible form with which one can produce more editing results.3. Two different types of non-iterative and global optimization algorithms are proposed. One is the global optimization algorithm based on Laplacian operator, which is designed to unify the triangle shape of meshes, and can be used to smooth or improve the quality of triangular meshes. The global shape and features of the original mesh can be preserved by adding a variety of constraints in the system such as vertex position, face barycenter constraints and coplanar constraints. The other one is the curvature-driven vertices flow algorithm which is designed to make mesh vertices flow from low-curvature regions to high-curvature regions, thus to enhance features of the mesh. It only needs to solve a linear least squares without any iterative scheme, which is efficient using the Cholesky factorization of symmetric positive definite matrices. Our global optimization algorithms are designed to improve the quality of triangles on new meshes produced by the decomposing and merging operations. After optimization, the mesh quality is greatly improved, which ensures that our method can produce high-quality mesh models.This paper provides an intuitive and simple sketch-based interface for both expert users and untrained users to model 3D meshes in an easy manner. We have proposed couples of interactive approaches for easy geometric modeling including the sketch-based mesh decomposition, editing, and feature aware optimization. Our approaches improve traditional modeling approach by involving human users in the process, yet minimizing user input and providing real time feedback.