Mesh Fusion Combining With Implicit Surfaces

Providing powerful and easy-to-use tools for users to create complex geometric object is one of the most challenging tasks for computer graphics community. Most commercial modeling systems are difficult to use for non-professional users, which limits their applications. Conversely, 3D sketching programs are good for novices, but the limited function make them only suitable for prototype design. How to achieve the balance between easy-to-use interfaces and powerful functions has confused researchers in geometric modeling area for a long time.Pasting and blending are two commonly used operations in image editing systems such as Photoshop. It has been a natural way to create complex images by applying the above two operations on several images coming from different sources. With the developments of data acquisition techniques, there have been lots of geometric models. If we can construct new models by compositing components from existing ones, the modeling efficiency for complex 3D objects will be improved greatly. However, it is difficult to perform pasting and blending between surfaces when they are represented by triangular meshes. In recent years, researchers have proposed various techniques for mesh fusion, however, most of them have compatible limitations.We present a new mesh composition paradigm based on the analysis of existing methods. We choose to composite objects together by constructing a transient part which smoothly connects these objects at their boundaries other than stitching them around the boundaries directly. In our new scheme, it becomes very easy to fuse multiple boundaries together in a session which is difficult for other mesh fusion frameworks. We propose two different fusion methods under this paradigm. We also proposed feasible solutions for the other related problems such as object segmentation, part placement and detail transition. Specifically, this dissertation has the following contributions:Mesh fusion using functional blending. We propose a new functional blending approach to specify the transient surface. A user can adjust the shape of the transient surface easily by specifying some parameters.Sketch based mesh fusion. We adopt the variational implicit surface as the transient surface. We present a sketch interface for users to specify the shape of the transient surface, and the sketch interface also improves the stability of the variational interpolation under sparse constraints.Implicit surface tessellation. We present two localized implicit surface tessellation algorithms to extract the part of the transient surface to be reserved automatically: Compound particle system provides a fast implicit surface visualization method meeting the requirements of interactive operations; Localized marching cubes method extracts the iso-surface with correct topology.Other algorithms related to mesh fusion. Mesh segmentation is a basic operation in mesh fusion system, we perform two segmentation tools allowing users to cut out the part of interest from models easily. When pasting a part onto a model, the first challenge is to find the transformation that tansfroms it into the appropriate coordinate frame with respect to the rest of the model. We provide a simple-interface for the user to position and orient parts when they are added to the new model. For the mesh fusion with highly detailed models, we provide a scheme to cover these details from the boundary to the whole transient area, and make the details coming from different sources blending together.