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.
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.
14767737
Dynamic co-scheduling of distributed computation and replication
We are interested in developing the infrastructural tools that allow a distributed data intensive computing environment to be shared by a group of collaborating but geographically separated researchers in an interactive manner, as opposed to a batch mode of operation. However, without advanced reservation, it is difficult to assure a certain level of performance on a large number of shared and heterogeneous servers. To achieve scalable parallel speedups in this scenario, we must closely integrate the management of computation and runtime data movement. In this paper, we first define the canonical scheduling problem for datasets distributed with k-way replication in the wide area. We then develop a dynamic co-scheduling algorithm that integrates the scheduling of computation and data movement. Using time-varying visualization as the driving application, we demonstrate that our co-scheduling approach improves not only application performance but also server utilization at a very reasonable cost.
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
9961789
Interactively visualizing procedurally encoded scalar fields
While interactive visualization of rectilinear gridded volume data sets can now be accomplished using texture mapping hardware on commodity PCs, interactive rendering and exploration of large scattered or unstructured data sets is still a challenging problem. We have developed a new approach that allows the interactive rendering and navigation of procedurally-encoded 3D scalar fields by reconstructing these fields on PC class graphics processing units. Since the radial basis functions (RBFs) we use for encoding can provide a compact representation of volumetric scalar fields, the large grid/mesh traditionally needed for rendering is no longer required and ceases to be a data transfer and computational bottleneck during rendering. Our new approach will interactively render RBF encoded data obtained from arbitrary volume data sets, including both structured volume models and unstructured scattered volume models. This procedural reconstruction of large data sets is flexible, extensible, and can take advantage of the Moore's Law cubed increase in performance of graphics hardware.
10826012
Agent-based workflow management in collaborative product development on the Internet
Product development is collaborative, involving multi-disciplinary functions and heterogeneous tools. Teamwork is essential through seamless tool integration and better co-ordination of human activities. This paper proposes to use workflow management as a mechanism to facilitate the teamwork in a collaborative product development environment where remote Web-based Decision Support Systems (TeleDSS) are extensively used by team members who are geographically distributed. The workflow of a project is modelled as a network. Its nodes correspond to the work (packages), and its edges to flows of control and data. The concept of agents is introduced to define nodes and the concept of messages to define edges. As a sandwich layer, agents act as special-purpose application clients for the remote TeleDSS application servers. Agents are delegated to manipulate the corresponding TeleDSS on behalf of their human users. Details of the proceedings are recorded by agents as their properties for future references or shared uses by other team members. Through flow messages, agents are able to share input and output data and request for remote services. One of the major contributions is that agents, once defined, can be reused for different projects without any changes.
205878217
Kings in quasi-transitive digraphs
Abstract A k -king in a digraph D is a vertex which can reach every other vertex by a directed path of length at most k . This definition generalizes the definition of a king in a tournament. We consider quasi-transitive digraphs - a generalization of tournaments recently investigated by the authors (Bang-Jensen and Huang, 1995). We prove that a quasi-transitive digraph has a 3-king if and only if it has an out-branching. We give several results on 3-kings in quasi-transitive digraphs which are analogous to well-known results about kings in tournaments.
21658897
A QoS-aware transcoding proxy using on-demand data broadcasting
The high diversity in the capabilities of various mobile devices such as display capabilities and computation power makes the design of mobile information systems more challenging. A transcoding proxy is placed between a client and an information server to coordinate the mismatch between what the server provides and what the client prefers. However, most research works in transcoding proxies in mobile computing environments are under the traditional client-server architecture and do not employ the data broadcast technique which is has been deemed a promising technique to design a power conservation, high scalable and high band-width utilization. In addition, the issue of QoS provision is also not addressed. In view of this, we design in this paper a QoS-aware transcoding proxy by utilizing the on-demand broadcasting technique. We first propose a QoS-aware transcoding proxy architecture, abbreviated as QTP, and model it as a queueing network. By analyzing the queueing network, several theoretical results are derived. We then propose a version decision policy and a service admission control scheme to provide QoS in QTP. The derived results are used to guide the execution of the proposed version decision policy and service admission control scheme to achieve the given QoS requirement. To measure the performance of QTP, several experiments are conducted. Experimental results show that the proposed scheme is more scalable than traditional client-server systems. In addition, the proposed scheme is able to effectively control the system load to attain the desired QoS
806919
Using Learning to Facilitate the Evolution of Features for Recognizing Visual Concepts
This paper describes a hybrid methodology that integrates genetic algorithms (GAs) and decision tree learning in order to evolve useful subsets of discriminatory features for recognizing complex visual concepts. A GA is used to search the space of all possible subsets of a large set of candidate discrimination features. Candidate feature subsets are evaluated by using C4.5, a decision tree learning algorithm, to produce a decision tree based on the given features using a limited amount of training data. The classification performance of the resulting decision tree on unseen testing data is used as the fitness of the underlying feature subset. Experimental results are presented to show how increasing the amount of learning significantly improves feature set evolution for difficult visual recognition problems involving satellite and facial image data. In addition, we also report on the extent to which other more subtle aspects of the Baldwin effect are exhibited by the system.