2129354
Visualization of neuronal fiber connections from DT-MRI with global optimization
Diffusion Tensor MRI (DT-MRI) provides valuable 3D data describing diffusion characteristics of water molecules in the human brain. From DT-MRI, it is hoped that neuronal fiber connections among cortical regions can be reliably extracted and adequately interpreted. To achieve this goal, several significant challenges persist. In this paper, by means of dynamic programming we have developed a global fiber reconstruction algorithm enabling efficient visualization of neuronal connections queried by both the start and end points on the fly. Besides an inherent ability to handle noisy datasets, our algorithm also naturally addresses situations where neuronal fibers branch or cross each other. We demonstrate the efficacy of our approach with visualization of neuronal connections among activated brain cortical regions detected by functional MRI (fMRI).
2068223
Edge Preservation in Volume Rendering Using Splatting
This paper presents a method to preserve sharp edge details in splatting for volume rendering. Conventional splatting algorithms produce fuzzy images for views close to the volume model. The lack of details in such views greatly hinders study and manipulation of data sets using virtual navigation. Our method applies a non-linear warping to the footprints of conventional splat and builds a table of footprints for different possible edge positions and edge strengths. When rendering, we pick a footprint from the table for each splat, based on the relative position of the voxel to the closest edge. Encouraging results have been achieved both for synthetic data and medical data.
8122062
High quality splatting and volume synthesis
Our recent improvements to volume rendering using splatting allow for an accurate functional reconstruction and volume integration, occlusion-based acceleration, post-rendering classification and shading, 3D texture mapping, bump mapping, anti-aliasing and gaseous animation. A pure software implementation requiring low storage and using simple operations has been implemented to easily support these operations. This paper presents a unified framework and discussion of these enhancements, as well as extensions to support hypertextures efficiently. Discussions on appropriate volume models for effective usage of these techniques is also presented.
1676234
A complete distance field representation
Distance fields are an important volume representation. A high quality distance field facilitates accurate surface characterization and gradient estimation. However, due to Nyquist's law, no existing volumetric methods based on the linear sampling theory can fully capture surface details, such as comers and edges, in 3D space. We propose a novel complete distance field representation (CDFR) that does not rely on Nyquist's sampling theory. To accomplish this, we construct a volume where each voxel has a complete description of all portions of surface that affect the local distance field. For any desired distance, we are able to extract a surface contour in true Euclidean distance, at any level of accuracy, from the same CDFR representation. Such point-based iso-distance contours have faithful per-point gradients and can be interactively visualized using splatting, providing per-point shaded image quality. We also demonstrate applying CDFR to a cutting edge design for manufacturing application involving high-complexity parts at unprecedented accuracy using only commonly available computational resources.
36043890
Remote Visualization by Browsing Image Based Databases with Logistical Networking
13952010
FastSplats: optimized splatting on rectilinear grids
Splatting is widely applied in many areas, including volume, point-based, and image-based rendering. Improvements to splatting, such as eliminating popping and color bleeding, occlusion-based acceleration, post-rendering classification and shading, have all been recently accomplished, These improvements share a common need for efficient framebuffer accesses. We present an optimized software splatting package, using a newly designed primitive, called FastSplat, to scan-convert footprints. Our approach does not use texture mapping hardware, but supports the whole pipeline in memory. In such an integrated pipeline, we are then able to study the optimization strategies and address image quality issues. While this research is meant for a study of the inherent trade-ofSof splatting, our renderer, purley in software, achieves 3 to 5 times speedups over a top-end texture hardware (for opaque data sets) implementation. We further propose a way of efSicient occlusion culling using a summed area table of opacity. 3 0 solid texturing and bump mapping capabilities are demonstrated to show the flexibility of such an integrated rendering pipeline. A detailed numerical error analysis, in addition to the performance and storage issues, is also presented. Our approach requires low storage and uses simple operations. Thus, it is easily implementable in hardware.
14327978
On Exploring the Power-Law Relationship in the Itemset Support Distribution
We identify and explore in this paper an important phenomenon which points out that the power-law relationship appears in the distribution of itemset supports. Characterizing such a relationship will benefit many applications such as providing the direction of tuning the performance of the frequent-itemset mining. Nevertheless, due to the explosive number of itemsets, it will be prohibitively expensive to retrieve characteristics of the power-law relationship in the distribution of itemset supports. As such, we also propose in this paper a valid and cost-effective algorithm, called algorithm PPL, to extract characteristics of the distribution without the need of discovering all itemsets in advance. Experimental results demonstrate that algorithm PPL is able to efficiently extract the characteristics of the power-law relationship with high accuracy.
12270343
SIFA: a scalable file system with intelligent file allocation
In this paper we propose and evaluate a new NAS based system which is a consolidated file system in a network environment. The consolidated file system utilizes storage boxes cooperating as peers to provide all file system services, and presents itself to its NFS clients as a unified storage server. We have prototyped several key operations in this system. To provide more performance insights, we build a comprehensive system simulator and conduct extensive performance studies for the system via the simulator This simulator has been run against a workload of a real Web server and the system behavior of this workload is studied. In light of the experimental results, a consolidated file system is being implemented in full scale.
2023739
Joint video scene segmentation and classification based on hidden Markov model
Video classification and segmentation are fundamental steps for efficient accessing, retrieval and browsing of large amounts of video data. We have developed a scene classification scheme using a hidden Markov model (HMM) based classifier. By utilizing the temporal behaviors of different scene classes, the HMM classifier can effectively classify video segments into one of the pre-defined scene classes. In this paper, we describe two approaches for joint video classification and segmentation based on a HMM, which works by searching for the most likely class transition path utilizing the dynamic programming technique.
14351696
A sufficient condition for a semicomplete multipartite digraph to be Hamiltonian
Abstract A multipartite tournament is an orientation of a complete k -partite graph for some k ⩾ 2. A factor of a digraph D is a collection of vertex disjoint cycles covering all the vertices of D . We show that there is no degree of strong connectivity which together with the existence of a factor will guarantee that a multipartite tournament is Hamiltonian. Our main result is a sufficient condition for a multipartite tournament to be Hamiltonian. We show that this condition is general enough to provide easy proofs of many existing results on paths and cycles in multipartite tournaments. Using this condition, we obtain a best possible lower bound on the length of a longest cycle in any strongly connected multipartite tournament.
14986573
Sharing ontology schema information for Web service integration
In spite of many standards efforts, Web services with similar or compatible functionalities often have heterogeneous semantics. One reason is the disparate ontologies used for service descriptions. In order to compare and compose Web services, the ability to merge different ontologies is essential. This paper describes an approach to align numerous, independently designed ontologies. Our approach is a completely automated one, without the need for prior agreement on semantics. It incorporates WordNet and heuristic reasoning and infers new knowledge by self-learning. Our system provides a solid base for the seamless integration of Web services.