16821874
Interactive Volume Navigation
Volume navigation is the interactive exploration of volume data sets by "flying" the viewpoint through the data, producing a volume rendered view at each frame. We present an inexpensive perspective volume navigation method designed to be run on a PC platform with accelerated 3D graphics hardware. The heart of the method is a two-phase perspective ray casting algorithm that takes advantage of the coherence inherent in adjacent frames during navigation. The algorithm generates a sequence of approximate volume-rendered views in a fraction of the time that would be required to compute them individually. The algorithm handles arbitrarily large volumes by dynamically swapping data within the current view frustum into main memory as the viewpoint moves through the volume. We also describe an interactive volume navigation application based on this algorithm. The application renders gray-scale, RGB, and labeled RGB volumes by volumetric compositing, allows trilinear interpolation of sample points, and implements progressive refinement during pauses in user input.
15918536
Protocols for distributed video streaming
With the explosive growth of video applications over the packet switched networks, many approaches have been proposed to stream video effectively over packet switched, best-effort networks. In our previous work, we proposed a framework with a receiver driven protocol to coordinate simultaneous video streaming from multiple senders to a single receiver in order to achieve higher throughput, and to increase tolerance to packet loss and delay due to network congestion. The receiver-driven protocol employs two algorithms: the rate allocation and packet partition. The rate allocation algorithm determines the sending rate for each sender while the packet partition algorithm ensures no sender sends the same packets, and at the same time, minimizes the probability of late packets. We extend the rate allocation scheme to be used with forward error correction (FEC) in order to minimize the probability of packet loss in a bursty loss environment such as one due to network congestion. Using both simulations and actual Internet experiments, we demonstrate the effectiveness of our rate allocation scheme in reducing packet loss, and hence, achieving higher visual quality for the streamed video.
17197783
Multiple sender distributed video streaming
With the explosive growth of video applications over the Internet, many approaches have been proposed to stream video effectively over packet switched, best-effort networks. We propose a receiver-driven protocol for simultaneous video streaming from multiple senders to a single receiver in order to achieve higher throughput, and to increase tolerance to packet loss and delay due to network congestion. Our receiver-driven protocol employs a novel rate allocation algorithm (RAA) and a packet partition algorithm (PPA). The RAA, run at the receiver, determines the sending rate for each sender by taking into account available network bandwidth, channel characteristics, and a prespecified, fixed level of forward error correction, in such a way as to minimize the probability of packet loss. The PPA, run at the senders based on a set of parameters estimated by the receiver, ensures that every packet is sent by one and only one sender, and at the same time, minimizes the startup delay. Using both simulations and Internet experiments, we demonstrate the effectiveness of our protocol in reducing packet loss.
15987233
Two-phase perspective ray casting for interactive volume navigation
Volume navigation is the interactive exploration of volume data sets by "flying" the view point through the data, producing a volume rendered view at each frame. The authors present an inexpensive perspective volume navigation method designed to run on a PC platform with accelerated 3D graphics hardware. They compute perspective projections at each frame, allow trilinear interpolation of sample points, and render both gray scale and RGB volumes by volumetric compositing. The implementation handles arbitrarily large volumes, by dynamically swapping data within the local depth-limited frustum into main memory as the viewpoint moves through the volume. They describe a new ray casting algorithm that takes advantage of the coherence inherent in adjacent frames to generate a sequence of approximate animated frames much faster than they could be computed individually. They also take advantage of the 3D graphics acceleration hardware to offload much of the alpha blending and resampling from the CPU.
12195287
Towards service collaboration model in grid-based zero latency data stream warehouse (GZLDSWH)
A grid-based zero-latency data stream warehouse (GZLDSWH), built upon a set of OGSI-based grid services and GT3 toolkit, overcomes the resource limitation issue for data stream processing without using traditional approximate approaches. However, due to its "automated event-based reaction" characteristic, the GZLDSWH requires a mechanism which allows the grid services to be able to work together to fulfill the common tasks. This paper describes the collaboration model for the grid services which enables the automation of the GZLDSWH in capturing and storing continuous data streams, making analytical processing, and reacting autonomously in near real time with some kinds of events based on well-established knowledge base.
16854388
Benchmarking Global Optimization and Constraint Satisfaction Codes
A benchmarking suite describing over 1000 optimization problems and constraint satisfaction problems covering problems from different traditions is described, annotated with best known solutions, and accompanied by recommended benchmarking protocols for comparing test results.
14182338
A Linear Algorithm for Polygonal Approximations of Thick Curves
The concept of fuzzy segment was introduced in [2]. In this paper we suggest a notion of strict fuzzy segment and provide a linear algorithm for recognizing it thanks to a simple property of convex hull. A linear method to decompose a thick curve into strict fuzzy segments is also given. The quality of decomposition can be easily controlled by setting two threshold values: the maximum order and the minimum density of the fuzzy segments. The algorithm is fast, practical and multi-purpose.
37264651
Rough Set Approach to Sunspot Classification Problem
This paper presents an application of hierarchical learning method based rough set theory to the problem of sunspot classification from satellite images. The Modified Zurich classification scheme [3] is defined by a set of rules containing many complicated and unprecise concepts, which cannot be determined directly from solar images. The idea is to represent the domain knowledge by an ontology of concepts – a treelike structure that describes the relationship between the target concepts, intermediate concepts and attributes. We show that such ontology can be constructed by a decision tree algorithm and demonstrate the proposed method on the data set containing sunspot extracted from satellite images of solar disk.
11789833
Collaborative Multidisciplinary Design in Virtual Environments
The application designers can usually define their own "virtual environments" by selecting the appropriate computing resources required or reuse and compose existing environments. The approach is generic by allowing various application domains to benefit from potential hardware and software resources located on remote computing facilities in a simple and intuitive way. The computing resources are defined by services made available as sets of standardized interfaces performing specific tasks: application workflow, input data streams, output visualization tools, monitoring facilities, etc. Services can be composed and hierarchically defined. Transparent access to heterogeneous hardware and software operating systems is guaranteed. An aero-elasticity example in airliner design is given