18506816
Manifold Parameterization
Manifold parameterization considers the problem of parameterizing a given triangular mesh onto another mesh surface, which could be particularly plane or sphere surfaces. In this paper we propose a unified framework for manifold parameterization between arbitrary meshes with identical genus. Our approach does this task by directly mapping the connectivity of the source mesh onto the target mesh surface without any intermediate domain and partition of the meshes. The connectivity graph of source mesh is used to approximate the geometry of target mesh using least squares meshes. A subset of user specified vertices are constrained to have the geometry information of the target mesh. The geometry of the mesh vertices is reconstructed while approximating the known geometry of the subset by positioning each vertex approximately at the center of its immediate neighbors. This leads to a sparse linear system which can be effectively solved. Our approach is simple and fast with less user interactions. Many experimental results and applications are presented to show the applicability and flexibility of the approach.
16978288
Interactive modeling of tree bark
There exist many computer graphics techniques which could achieve high quality tree generation. However, only few works focus on realistic modeling of tree bark. Difficulties lie in the complex appearance of the bark surfaces from a single image. We address three main issues here: feature specification; height field assignment; and texture correction. For feature specification, we use texton channel analysis to specify a variant of common bark features, inluding ironbark, vertical and horizontal fractures, tessellation, furrowed cork, and lenticels. For height field assignment, we develop an intuitive and easy-to-use user interface (UI). Here similarity-based texture editing is used for assigning height fields within a texton channel mask. For texture correction, we use the modeled height fields to eliminate the underlying lighting effects in a captured texture. Our modeling system is image-based: it takes as input a bark image and produces as output a textured height field representing a bark sample. We demonstrate that out method is an effective and easy-to-use technique to interactively model a variety of photo realistic bark surfaces.
2470562
Stretch-based tetrahedral mesh manipulation
We present a novel least scaling distortion metric to measure the deformation distortion for tetrahedral meshes. The stretch-like metric is a combination of Jacobian matrix norm and tetrahedron volume and has the properties of good shape preservation and rotation invariance. Based on our metric, we propose a uniform non-linear optimization solution to a variety of tetrahedral mesh manipulation applications including shape deformation, interpolation, deformation transfer, and deformation learning. Our approach can produce volume preserving and flip free tetrahedral mesh results, which performs much better than the previous tetrahedral manipulation approaches. We also demonstrate an efficient and practical application using free-form deformation technique. The object is embedded in a rough control tetrahedral mesh and deformed by editing the tetrahedral mesh with various constraints. Each vertex of the object can be obtained by its barycentric coordinates according to its embedding tetrahedron of the control tetrahedral mesh.
7311513
Polygonal Shape Blending with Topological Evolutions
This paper presents a new general approach to blend 2D shapes with different topologies. All possible topological evolutions are classified into three types by attaching three different topological cells. This formalism is resulted from Morse theory on the behavior of the 3D surface around a non-degenerate critical point. Also we incorporate degenerate topological evolutions into our framework which produce more attractive morphing effects. The user controls the morph by specifying the types of topological evolutions as well as the feature correspondences between the source and target shapes. Some techniques are also provided to control the vertex path during the morphing process. The amount of user input required to produce a morph is directly proportional to the amount of control the user wishes to impose on the process. The user may allow the system to automatically generate the morph as well. Our approaches are totally geometric based and are easy and fast enough in fully interactive time. Many experimental results show the applicability and flexibility of our approaches.
3249877
Dual Laplacian editing for meshes
Recently, differential information as local intrinsic feature descriptors has been used for mesh editing. Given certain user input as constraints, a deformed mesh is reconstructed by minimizing the changes in the differential information. Since the differential information is encoded in a global coordinate system, it must somehow be transformed to fit the orientations of details in the deformed surface, otherwise distortion will appear. We observe that visually pleasing deformed meshes should preserve both local parameterization and geometry details. We propose to encode these two types of information in the dual mesh domain due to the simplicity of the neighborhood structure of dual mesh vertices. Both sets of information are nondirectional and nonlinearly dependent on the vertex positions. Thus, we present a novel editing framework that iteratively updates both the primal vertex positions and the dual Laplacian coordinates to progressively reduce distortion in parametrization and geometry. Unlike previous related work, our method can produce visually pleasing deformations with simple user interaction, requiring only the handle positions, not local frames at the handles.
12726241
Automatic detection of fragments in dynamically generated web pages
Dividing web pages into fragments has been shown to provide significant benefits for both content generation and caching. In order for a web site to use fragment-based content generation, however, good methods are needed for dividing web pages into fragments. Manual fragmentation of web pages is expensive, error prone, and unscalable. This paper proposes a novel scheme to automatically detect and flag fragments that are cost-effective cache units in web sites serving dynamic content. We consider the fragments to be interesting if they are shared among multiple documents or they have different lifetime or personalization characteristics. Our approach has three unique features. First, we propose a hierarchical and fragment-aware model of the dynamic web pages and a data structure that is compact and effective for fragment detection. Second, we present an efficient algorithm to detect maximal fragments that are shared among multiple documents. Third, we develop a practical algorithm that effectively detects fragments based on their lifetime and personalization characteristics. We evaluate the proposed scheme through a series of experiments, showing the benefits and costs of the algorithms. We also study the impact of adopting the fragments detected by our system on disk space utilization and network bandwidth consumption.
10661094
Designing information systems in social context: a goal and scenario modelling approach
In order to design a better information system, a designer would like to have notations to visualize how design experts' know-how can be applied according to one's specific social and technology situation. We propose the combined use of a goal-oriented requirements language (GRL) and a scenario-oriented notation Use Case Maps (UCM) for representing design knowledge of information systems. Goal-oriented modelling is used throughout the requirements and design process. In GRL, goals are used to depict business objectives and system requirements, both functional and non-functional. Tasks are used to represent different ways for achieving goals. Means-ends reasoning is used to explore alternative solutions and their operationalizations into implementable system constructs. Social context is modelled in terms of dependency relationships among agents and roles. Scenarios expressed in UCM are used to describe elaborated business processes or workflow. The complementary use of goal-oriented modelling with GRL and scenario modelling with UCM is illustrated with an example of designing a web-based training system.
17004866
Query routing in large-scale digital library systems
Modern digital libraries require user-friendly and yet responsive access to the rapidly growing, heterogeneous, and distributed collection of information sources. The increasing volume and diversity of digital information available online have led to a growing problem that conventional data management systems do not have, namely finding which information sources out of many candidate choices are the most relevant to answer a given user query. It refer to this problem as the query routing problem. In this paper we introduce the notation and issues of query routing, and present a practical solution for designing a scalable query routing system based on multilevel progressive pruning strategies. The key idea is to create and maintain user query profiles and source capability profiles independently, and to provide algorithms that can dynamically discover relevant information sources for a given query through the smart use of user query profiles and source capability profiles, including the mechanisms for interleaving query routing with query parallelization and query execution process to continue the pruning at run-time. Comparing with the keyword-based indexing techniques adopted in most of the search engines and software, our approach offers fine-granularity of interest matching, thus it is more powerful and effective for handling queries with complex conditions.
534672
Cluster rendering of skewed datasets via visualization
Information Visualization is commonly recognized as a useful method for understanding sophistication in large datasets. In this paper, we introduce a flexible clustering approach with visualization techniques, aiming at the datasets that have skewed cluster distribution. This paper has three contributions. First, we propose a framework Vista that incorporates information visualization methods into the clustering process in order to enhance the understanding of the intermediate clustering results and allow user to revise the clustering results easily. Second, we develop a visualization model that maps multidimensional dataset to 2D visualizations while preserving or partially preserving clusters. Third, based on the visualization model, a set of operating rules are proposed to guide the user rendering clusters efficiently. Experiments show that the Vista system can yield lower error rates for real datasets than typical automated algorithms.
3052639
Connectivity based node clustering in decentralized peer-to-peer networks
Connectivity based node clustering has wide ranging applications in decentralized peer-to-peer (P2P) networks such as P2P file sharing systems, mobile ad-hoc networks, P2P sensor networks and so forth. We describe a connectivity-based distributed node clustering scheme (CDC). This scheme presents a scalable and an efficient solution for discovering connectivity based clusters in peer networks. In contrast to centralized graph clustering algorithms, the CDC scheme is completely decentralized and it only assumes the knowledge of neighbor nodes, instead of requiring a global knowledge of the network (graph) to be available. An important feature of the CDC scheme is its ability to cluster the entire network automatically or to discover clusters around a given set of nodes. We provide experimental evaluations of the CDC scheme, addressing its effectiveness in discovering good quality clusters. Our experiments show that utilizing message-based connectivity structure can considerably reduce the messaging cost, and provide better utilization of resources, which in turn improves the quality of service of the applications executing over decentralized peer-to-peer networks.