32161993
Emerging Web Graphics Standards and Technologies
Migrating computer graphics to the Web poses several problems, but with new standards and technology advances, graphics applications can balance latency and bandwidth constraints with image quality. The paper discusses Web graphics standards, distributed virtual environments and virtual humans.
6487445
Incremental rendering of deformable trimmed NURBS surfaces
Trimmed NURBS surfaces are often used to model smooth and complex objects. Unfortunately, most existing hardware graphics accelerators cannot render them directly. Although there are a lot of methods proposed to accelerate the rendering of such surfaces, majority of them are based on tessellation, which is developed primarily for handling non-deforming objects. For an object that may deform in run-time, such as clothing, facial expression, human and animal character, the tessellation process will need to be performed repeatedly while the object is deforming. However, as the tessellation process is very time consuming, interactive display of deforming objects is difficult. This explains why deformable objects are rarely used in virtual reality applications. In this paper, we present a efficient method for incremental rendering of deformable trimmed NURBS surfaces. This method can handle both trimmed surface deformation and trimming curve deformation. Experimental results show that our method performs significantly faster than the method used in OpenGL.
17571347
A multi-server architecture for distributed virtual walkthrough
CyberWalk is a distributed virtual walkthrough system that we have developed. It allows users at different geographical locations to share information and interact within a common virtual environment (VE) via a local network or through the Internet. In this paper, we illustrate that when the number of users exploring the VE increases, the server will quickly become the bottleneck. To enable good performance, CyberWalk utilizes multiple servers and employs an adaptive data partitioning techniques to dynamically partition the whole VE into regions. All objects within each region will be managed by one server. Under normal circumstances, when a viewer is exploring a region, the server of that region will be responsible for serving all requests from the viewer. When a viewer is crossing the boundary of two or more regions, the servers of all the regions involved will be serving requests from the viewer since the viewer might be able to view objects within all those regions. We evaluate the performance of this multi-server architecture of CyberWalk via a detail simulation model.
8615414
Collaborative distributed virtual sculpting
A lot of effort is now being put into developing collaborative distributed virtual environments. However very few projects address collaborative virtual sculpting in which the shapes of the target objects are likely changing continuously. Some major issues including user interaction, data transmission, concurrent object editing by multiple clients and rendering of deforming objects must be addressed in a real-time context. We propose a framework for collaborative virtual sculpting in a distributed virtual environment. The system is based on a hybrid model which merges the client-server and the peer-to-peer architectures to allow fast data replication. To support real-time deformation and rendering of deformable objects, we model each of these objects using NURBS surfaces and render them using the real-time deformable NURBS rendering method that we have developed. We present a data structure for the transmission of these deformable objects. We also introduce the idea of editing region and the corresponding locking mechanism for simultaneous editing of the same object by multiple clients. Toward the end of the paper we show some performance results of the prototype system.
2441510
Interactive Rendering of Deforming NURBS Surfaces
The non-uniform rational B-splines (NURBS) has been widely accepted a s a standard tool f or geometry representation and design. Its r ich g eometric properties allow it t o represent both analytic shapes and free-form curves and surfaces precisely. Moreover, a set of tools is available for shape modification or more implicitly, object deformation. Existing NURBS rendering methods include de Boor algorithm, Oslo algorithm, Shantz’s adaptive forward differencing algorithm and Silbermann’s high speed implementation o f NURBS. However, these methods consider only speeding u p the rendering p rocess of individual f rames. Recently, Kumar et al. proposed an incremental method for rendering NURBS surfaces, but it is still limited to static surfaces. In realtime applications such a s virtual reality, interactive display is needed. If a virtual environment contains a lot of deforming objects, these methods cannot provide a good solution. In this paper, we propose an efficient method for interactive rendering of deformable objects by maintaining a polygon model of each d eforming NURBS surface and a daptively refining the resolution o f the polygon model. We also look at how this method may be applied to multi-resolution modelling.
17558341
Adaptive partitioning for multi-server distributed virtual environments
A distributed virtual environment (DVE) allows users at different geographical locations to share information and interact within a common virtual environment (VE) via a local network or through the Internet. However, when the number of users exploring the VE increases, the server will quickly become the bottleneck. To enable good performance, we are currently developing a multi-server DVE prototype. In this paper, we describe an adaptive data partitioning technique to dynamically partition the whole VE into regions. All objects within each region will be managed by a single server. As the loading of the servers changes, we show how it can be redistributed while minimizing the communication cost. Our initial results show that the proposed adaptive partitioning technique significantly improves the performance of the overall system.
11226444
Locality-conscious workload assignment for array-based computations in MPSOC architectures
While the past research discussed several advantages of multiprocessor-system-on-a-chip (MPSOC) architectures from both area utilization and design verification perspectives over complex single core based systems, compilation issues for these architectures have relatively received less attention. Programming MPSOCs can be challenging as several potentially conflicting issues such as data locality, parallelism and load balance across processors should be considered simultaneously. Most of the compilation techniques discussed in the literature for parallel architectures (not necessarily for MPSOCs) are loop based, i.e., they consider each loop nest in isolation. However, one key problem associated with such loop based techniques is that they fail to capture the interactions between the different loop nests in the application. This paper takes a more global approach to the problem and proposes a compiler-driven data locality optimization strategy in the context of embedded MPSOCs. An important characteristic of the proposed approach is that, in deciding the workloads of the processors (i.e., in parallelizing the application) it considers all the loop nests in the application simultaneously. The authors' experimental evaluation with eight embedded applications showed that the global scheme brings significant power/performance benefits over the conventional loop based scheme.
15048202
Protection and guarantee for voice and video traffic in IEEE 802.11e wireless LANs
In order to support multimedia applications such as voice and video over the wireless medium, a contention-based channel access function, called enhanced distributed coordination function (EDCF), is being developed in the emerging standard IEEE 802.11e. In EDCF, differentiated services are provided for different traffic classes. In this paper, we propose a two-level protection and guarantee mechanism for voice and video traffic in IEEE 802.11e wireless LANs. In the first-level protection, the existing voice and video flows are protected from the new and other existing voice and video flows. In the second-level protection, the voice and video flows are protected from the best-effort data traffic. For each protection level, a couple of protection mechanisms are proposed. Extensive simulation results show that the proposed two-level protection and guarantee mechanism is very effective in terms of protecting and guaranteeing existing voice and video flows as well as fully utilizing the channel capacity
17450841
An information concierge for the Web
WWW Information Collection, Collaging and Programming (WICCAP) system is a software system for the generation of logical views of web resources, and the extraction of desired information in the form of a structured document. It is designed to enable people to obtain information of interests in a simple and effective manner as well as to make information from the WWW accessible to applications so as to afford automation, inter-operation and Web-awareness among services. A key factor in making this system useful in practice is that it provides tools to automate and facilitate the process of constructing logical representation of websites, to identify and define information of interest, and to retrieving them. In this paper we present the design of the WICCAP system and its two main components, namely Mapping Wizard and Network Extraction Agent.
2691860
Design and Management of 3D Chip Multiprocessors Using Network-in-Memory
Long interconnects are becoming an increasingly important problem from both power and performance perspectives. This motivates designers to adopt on-chip network-based communication infrastructures and three-dimensional (3D) designs where multiple device layers are stacked together. Considering the trends towards increasing use of chip multiprocessing, it is timely to consider 3D chip multiprocessor design and memory networking issues, especially in the context of data management in large L2 caches. The overall goal of this paper is to study the challenges for L2 design and management in 3D chip multiprocessors. Our first contribution is to propose a router architecture and a topology design that makes use of a network architecture embedded into the L2 cache memory. Our second contribution is to demonstrate, through extensive experiments, that a 3D L2 memory architecture generates much better results than the conventional two-dimensional (2D) designs under different number of layers and vertical (inter-wafer) connections. In particular, our experiments show that a 3D architecture with no dynamic data migration generates better performance than a 2D architecture that employs data migration. This also helps reduce power consumption in L2 due to a reduced number of data movements
1037934
A visual tool for building logical data models of websites
Information sources over the WWW contain a large amount of data organized according to different interests and values. Thus, it is important that facilities are there to enable users to extract information of interest in a simple and effective manner. To do this, We propose the Wiccap Data Model, an XML data model that maps Web information sources into commonly perceived logical models, so that information can be extracted automatically according to users' interests. To accelerate the creation of data models, we have implemented a visual tool, called the Mapping Wizard, to facilitate and automate the process of producing Wiccap Data Models. Using the tool, the time required to construct a logical data model for a given website is significantly reduced.