14081654
Real-time rendering of deformable parametric free-form surfaces
Deformable objects are required to improve the realism of virtual reality applications. They are particularly useful in modeling clothes, facial expression, human and animal characters. A common method to render these objects is by tessellation. However, the tessellation process is computationally very expensive. If the object deforms, we need to retessellate the surface every frame, as its shape changes from one frame to the next. This computational burden poses a significant challenge to the real-time rendering of deformable objects. Consequently, deformable objects are seldom incorporated in existing virtual reality systems. In this paper, we present an incremental method for rendering deformable objects modeled by parametric free-form surfaces. We also introduce two new frame coherence techniques for crack prevention and parameter caching. Finally, we present a single hierarchical data structure which provides a multi-resolution representation of the object model.
41742727
Efficient rendering of deformable objects for real-time applications
Deformable objects can be used to model soft objects such as clothing, human faces and animal characters. They are important as they can improve the realism of the applications. However, most existing hardware accelerators cannot render deformable objects directly. A tessellation process is often used to convert a deformable object into polygons so that the hardware graphics accelerator may render them. Unfortunately, this tessellation process is computationally very expensive. While the object is deforming, the tessellation process needs to be performed repeatedly to convert the deforming objects into polygons. As a result, deformable objects are seldom used in real-time applications such as virtual environments and computer games. Since trimmed NURBS surfaces are often used to represent deformable objects, in this paper we present an efficient method for incremental rendering of deformable trimmed NURBS surfaces. A trimmed NURBS surface typically deforms through the deformation of the trimmed NURBS surface and/or the trimming curve. Our method handles both trimmed surface deformation as well as trimming curve deformation. Experimental results show that our method performs significantly faster than the method used in OpenGL and can be used in real-time applications, such as computer games. Copyright © 2006 John Wiley & Sons, Ltd.
16124997
GameOD: an internet based game-on-demand framework
Multiplayer online 3D games are becoming very popular in recent years. However, existing games require the complete game content to be installed prior to game playing. Since the content is usually large in size, it may be difficult to run these games on a PDA or other handheld devices. It also pushes game companies to distribute their games as CDROMs/DVDROMs rather than online downloading. On the other hand, due to network latency, players may perceive discrepant status of some dynamic game objects. In this paper, we present a game-on-demand (GameOD) framework to distribute game content progressively in an on-demand manner. It allows critical contents to be available at the players' machines in a timely fashion. We present a simple distributed synchronization method to allow concurrent players to synchronize their perceived game status. Finally, we show some performance results of the proposed framework.
9839431
VSculpt : a distributed virtual sculpting environment for collaborative design
A collaborative virtual sculpting system supports a team of geographically separated designers/engineers connected by networks to participate in designing three-dimensional (3D) virtual engineering tools or sculptures. It encourages international collaboration at a minimal cost. However, in order for the system to be useful, two factors need to be addressed: intuitiveness and real-time interaction. Although a lot of effort has been put into developing virtual sculpting environments, only limited work addresses collaborative virtual sculpting. This is because in order to support real-time collaborative virtual sculpting, many challenging issues need to be addressed. We propose a collaborative virtual sculpting framework, called VSculpt. Through adapting some techniques we developed earlier and integrating them with some techniques developed here, the proposed framework provides a real-time intuitive environment for collaborative design. In particular, it addresses issues on efficient rendering and transmission of deformable objects, intuitive object deformation using the CyberGlove and concurrent object deformation by multiple clients. We demonstrate and evaluate the performance of the proposed framework through a number of experiments.
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.
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
8583268
Proportional degradation services in wireless/mobile adaptive multimedia networks
Adaptive multimedia services are very attractive since resources in wireless/mobile networks are relatively scarce and widely variable, and more importantly the resource fluctuation caused by mobility and channel fading can be mitigated using adaptive services. Therefore, there are extensive research activities on Quality of Service (QoS), call admission control, as well as bandwidth degradation and adaptation for adaptive multimedia services in wireless/mobile networks in recent years. However, fairness of bandwidth degradation has largely been ignored in previous work and remains an important issue in adaptive multimedia service provisioning. In this paper, we propose and study proportional degradation service provisioning in wireless/mobile networks that offer multiple classes of adaptive multimedia services. The proposed proportional degradation fairness model guarantees the proportional bandwidth degradation among different classes of services. Two proportional degradation scenarios are studied in this paper. In the first scenario, we study the proportional degradation provisioning with two QoS parameters for adaptive multimedia: the degradation ratio (DR) and the degradation degree (DD). In the second scenario, we study the proportional degradation provisioning with a new QoS parameter for adaptive multimedia: the degradation area (DA). For each scenario, based on the QoS parameters, proportional degradation adaptation algorithms are proposed to approximate the proportional degradation model, to fairly adapt calls' degradations, to utilize the system resource efficiently, as well as to optimize QoS parameters. Performance studies show that in the first scenario, proportional DR has been achieved very well, whereas proportional DD has not been well achieved. In other words, DR outperforms DD in terms of proportional degradation. In the second scenario, proportional DA has been well achieved. Furthermore, bandwidth resources have been efficiently utilized and DA has been minimized. Copyright © 2004 John Wiley & Sons, Ltd.
8773045
Characterizing and Exploiting Reference Locality in Data Stream Applications
In this paper, we investigate a new approach to process queries in data stream applications. We show that reference locality characteristics of data streams could be exploited in the design of superior and flexible data stream query processing techniques. We identify two different causes of reference locality: popularity over long time scales and temporal correlations over shorter time scales. An elegant mathematical model is shown to precisely quantify the degree of those sources of locality. Furthermore, we analyze the impact of locality-awareness on achievable performance gains over traditional algorithms on applications such asMAX-subset approximate sliding window join and approximate count estimation. In a comprehensive experimental study, we compare several existing algorithms against our locality-aware algorithms over a number of real datasets. The results validate the usefulness and efficiency of our approach.
17981801
Studying storage-recomputation tradeoffs in memory-constrained embedded processing
Fueled by an unprecedented desire for convenience and self-service, consumers are embracing embedded technology solutions that enhance their mobile lifestyles. Consequently, we witness an unprecedented proliferation of embedded/mobile applications. Most of the environments that execute these applications have severe power, performance, and memory space constraints that need to be accounted for. In particular, memory limitations can present serious challenges to embedded software designers. The current solutions to this problem include sophisticated packaging techniques and code optimizations for effective memory utilization. While the first solution is not scalable, the second one is restricted by intrinsic data dependences in the code that prevent code restructuring. In this paper, we explore an alternate approach for reducing memory space requirements of embedded applications. The idea is to re-compute the result of a code block (potentially multiple times) instead of storing it in memory and performing a memory operation whenever needed. The main benefit of this approach is that it reduces memory space requirements, that is, no memory space is reserved for storing the result of the code block in question.