819318
Feature Sensitive Out-of-Core Chartification of Large Polygonal Meshes
Mesh chartification is an important tool for processing meshes in various applications. In this paper, we present a novel feature sensitive mesh chartification technique that can handle huge meshes with limited main memory. Our technique adapts the mesh chartification approach using Lloyd-Max quantization to out-of-core processing. While the previous approach updates chartification globally at each iteration of Lloyd-Max quantization, we propose a local update algorithm where only a part of the chartification is processed at a time. By repeating the local updates, we can obtain a chartification of a huge mesh that cannot fit into the main memory. We verify the accuracy of the serialized local updates by comparing the results with the global update approach. We demonstrate that our technique can successfully process huge meshes for applications, such as mesh compression, shape approximation, and remeshing.
10508365
Motif analysis of noisy regular textures
Abstract A regular texture contains a periodic arrangement of a determinable pattern. Motifs of a regular texture are the minimal parallelogrammic sub-regions that can reproduce the texture by tiling. A motif extracted from a regular texture can be used for texture reproduction, texture recognition, and texture compression. However, it is not simple to accurately capture a motif of a regular texture, as the motif may be non-rectangular or arranged in an arbitrary direction. Moreover, when the texture contains additive noises, such as are created by the scanning process, motif analysis becomes more difficult. In this paper, we present an algorithm to obtain a motif of a noisy regular texture in O( mn log mn ) time, where m × n is the size of the texture. The analysis examples demonstrate that the proposed algorithm can robustly derive motifs of noisy regular textures.
8933894
Out-of-Core Remeshing of Large Polygonal Meshes
We propose an out-of-core method for creating semi-regular surface representations from large input surface meshes. Our approach is based on a streaming implementation of the MAPS remesher of Lee et al. Our remeshing procedure consists of two stages. First, a simplification process is used to obtain the base domain. During simplification, we maintain the mapping information between the input and the simplified meshes. The second stage of remeshing uses the mapping information to produce samples of the output semi-regular mesh. The out-of-core operation of our method is enabled by the synchronous streaming of a simplified mesh and the mapping information stored at the original vertices. The synchronicity of two streaming buffers is maintained using a specially designed write strategy for each buffer. Experimental results demonstrate the remeshing performance of the proposed method, as well as other applications that use the created mapping between the simplified and the original surface representations
7108445
Mesh parameterization with a virtual boundary
Parameterization of a 3D triangular mesh is a fundamental problem in various applications of meshes. The convex combination approach is widely used for parameterization because of its good properties, such as fast computation and one-to-one embedding. However, the approach has a drawback: most boundary triangles have high distortion in the embedding compared with interior ones. In this paper, we present an extension of the convex combination approach that resolves the drawback by using a virtual boundary. Since the virtual boundary is fixed onto a given convex polygon instead of the real boundary, the real boundary triangles can better reflect the shape of the corresponding 3D triangles. The proposedapproach obtains a parameterization of a 3D mesh with less d istortion than with the original convex combination approach. r 2002 Elsevier Science Ltd. All rights reserved.
28687567
Motion retargeting and evaluation for VR-based training of free motions
Virtual reality (VR) has emerged as one of the important and effective tools for education and training. Most VR-based training systems are situation based, where the trainees are trained for discrete decision making in special situations presented by the VR environments. In contrast, this paper discusses the application of VR to a different class of training, for learning free motion, often required in sports and the arts. We propose a VR-based motion-training framework that contains an intuitive motion-guiding interface, posture-oriented motion retargeting, and an evaluation and advice scheme for corrective feedback. Applications of the proposed framework to simple fencing training and a dance imitation game are demonstrated .
9314363
Feature sensitive mesh segmentation with mean shift
Feature sensitive mesh segmentation is important for many computer graphics and geometric modeling applications. In this paper, we develop a mesh segmentation method, which is capable of producing high-quality shape partitioning. It respects fine shape features and works well on various types of shapes, including natural shapes and mechanical parts. The method combines a procedure for clustering mesh normals with a modification of the mesh clarification technique. For clustering of mesh normals, we adopt Mean Shift, a powerful general purpose technique for clustering scattered data. We demonstrate advantages of our method by comparing it with two state-of-the-art mesh segmentation techniques.
31361010
Mammogram Analysis Using Two-Dimensional Autoregressive Models: Sufficient or Not?
Two-dimensional (2–D) autoregressive (AR) models have been used as one of the methods to characterise the textures of tumours in mammograms. Previously, the 2–D AR model coefficients were estimated for the block containing the tumour and the blocks in its 3 × 3 neighbourhood. In this paper, the possibility of having the estimated set of AR model coefficients of the block containing the tumour as a unique set of AR model coefficients for the entire mammogram is looked into. Based on the information given from the MiniMammography database, the possible number of blocks of the same size of the block containing the tumour is obtained from the entire mammogram and for each block a set of AR model coefficients is estimated using a method that combines both the Yule-Walker system of equations and the Yule-Walker system of equations in the third-order statistical domain. These sets of AR model coefficients are then compared. The simulation results show that 98.6% of the time we can not find another set of AR model coefficients representing the blocks of pixels in the possible neighbourhood of the entire mammogram for the data (95 mammograms with 5 of them having two tumours) available in the MiniMammography database.
11512918
Combining Source- and Localized Recovery to Achieve Reliable Multicast in Multi-hop Ad Hoc Networks
This paper proposes a novel reliable multicast transport protocol for multi-hop, wireless ad hoc networks (or MANETs). To recover from the different types of losses that may occur in MANETs, our Reliable Adaptive Congestion-controlled Transport protocol, or Re-ACT, combines source-based congestion- and error control with receiver-initiated localized recovery. While the latter attempts to recover localized losses (e.g., caused by transmission errors), the former is invoked only for losses and congestion that could not be recovered locally (e.g., caused by global congestion). Loss differentiation is an important component of ReACT and uses medium access control (MAC) layer information to distinguish between different types of losses. Through extensive simulations, we evaluate ReACT’s performance under a variety of MANET scenarios, including different offered load and mobility conditions, and compare it against a strictly end-to-end (i.e., no localized recovery) scheme. Our results show that ReACT is the best performer in terms of reliability. Our results also showcase the effect of ReACT’s local recovery mechanism which quickly corrects error- and path breakage induced losses and thus manages to prevent the source from reducing its rate unnecessarily , thus achieving significant throughput improvement with lower overhead when compared to the strictly end-to-end protocol.
9065684
NodeWiz: peer-to-peer resource discovery for grids
Efficient resource discovery based on dynamic attributes such as CPU utilization and available bandwidth is a crucial problem in the deployment of computing grids. Existing solutions are either centralized or unable to answer advanced resource queries (e.g., range queries) efficiently. We present the design of NodeWiz, a grid information service (CIS) that allows multi-attribute range queries to be performed efficiently in a distributed manner. This is obtained by aggregating the directory services of individual organizations in a peer-to-peer information service.
33132157
Updatability in Federated Database Systems
It is important to support updates in federated database systems. However, not all updates on the federated schema are possible because some may violate certain constraints in the local databases which are involved in the federation. In this paper, we give a formal framework which characterizes the conditions under which a federated schema object type is updatable. We study the steps involved to systematically map an update request on an external view of a federated schema into the equivalent update(s) on the local databases. We also consider the situation where semantically equivalent object types may not model exactly the same set of objects in the real world. We ensure that the set constraints (EQUAL, SUBSET, DISJOINT) between the instance sets of equivalent object types are not violated after an update.
5399807
Embedding of Complete Binary Trees into Meshes with Row-Column Routing
This paper considers the problem of embedding complete binary trees into meshes using the row-column routing and obtained the following results: a complete binary tree with 2/sup p/-1 nodes can be embedded (1) with link congestion one into a /sup 9///sub 8//spl radic/(2/sup p/)/spl times//sup 9///sub 8//spl radic/(2/sup p/) mesh when p is even and a /spl radic/(/sup 9///sub 8/2/sup p/)/spl times//spl radic/(/sup 9///sub 8/2/sup p/) mesh when p is odd, and (2) with link congestion two into a /spl radic/(2/sup p/)/spl times//spl radic/(2/sup p/) mesh when p is even, and a /spl radic/(2/sup p-1/)/spl times//spl radic/(2/sup p-1/) mesh when p is odd.