One of the main scientific goals of visualization is the development of algorithms and appropriate data models which facilitate interactive visual analysis and direct manipulation of the increasingly large data sets w...
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One of the main scientific goals of visualization is the development of algorithms and appropriate data models which facilitate interactive visual analysis and direct manipulation of the increasingly large data sets which result from simulations running on massive parallel computer systems, from measurements employing fast high-resolution sensors, or from large databases and hierarchical information spaces. This task can only be achieved with the optimization of all stages of the visualization pipeline: filtering, compression, and feature extraction of the raw data sets, adaptive visualization mappings which allow the users to choose between speed and accuracy, and exploiting new graphics hardware features for fast and high-quality rendering. The recent introduction of advanced programmability in widely available graphics hardware has already led to impressive progress in the area of volume visualization. However, besides the acceleration of the final rendering, flexible graphics hardware is increasingly being used also for the mapping and filtering stages of the visualization pipeline, thus giving rise to new levels of interactivity in visualization applications. The talk will present recent results of applying programmable graphics hardware in various visualization algorithms covering volume data, flow data, terrains, NPR rendering, and distributed and remote applications.
Best quadratic simplicial spline approximations can be computed. using quadratic Bernstein-Bezier basis functions. by identifying and bisecting simplicial elements with largest errors. Our method begins with an initia...
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ISBN:
(纸本)0819444057
Best quadratic simplicial spline approximations can be computed. using quadratic Bernstein-Bezier basis functions. by identifying and bisecting simplicial elements with largest errors. Our method begins with an initial triangulation of the domain: a best quadratic spline approximation is computed: errors are computed for all simplices. and simplices of maximal error are subdivided. This process is repeated until a user-specified global error tolerance is met. The initial approximations for the unit square and cube are given by two quadratic triangles and five quadratic tetrahedra-respectively. Our more complex triangulation and approximation method that respects field discontinuities and geometrical features allows us to better approximate data. data is visualized by using the hierarchy of increasingly better quadratic approximations generated by this process. Many visualization problems arise for quadratic elements. First tessellating quadratic elements with smaller linear ones and then rendering the smaller linear elements is one way to visualize quadratic elements. Our results show a significant reduction in the number of simplices required to approximate data sets when using quadratic elements as compared to using linear elements.
Communication is a central activity in command and control. However, analysing communication using linear transcription of large amounts of sequential data is tedious and tune consuming. This paper describes an altern...
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ISBN:
(纸本)0769516564
Communication is a central activity in command and control. However, analysing communication using linear transcription of large amounts of sequential data is tedious and tune consuming. This paper describes an alternative approach to communication analysis based on visual exploration of abstract representations of communication. It introduces a visualisation technique based on the Attribute Explorer. The technique was implemented in a visualisation component embedded in a framework for coordinated presentation of temporal data. It is demonstrated using authentic communication data from a military exercise and a rescue operation.
The modeling of convective flows based on a 3D lattice Boltzmann approach for low Mach number flows with variable density combined with a large eddy turbulence model is presented. The ability to handle non-Boussinesq ...
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The modeling of convective flows based on a 3D lattice Boltzmann approach for low Mach number flows with variable density combined with a large eddy turbulence model is presented. The ability to handle non-Boussinesq density variation problems is depicted for two-dimensional Rayleigh-Benard convection at a Rayleigh number Ra = 800,000. A complex three-dimensional example shows the status of our work with respect to turbulent flow in and around a building, so far without consideration of the energy equation in the full scale 3D case. Integrated within a CAD environment, the spatial geometric model, based on an IFC building product data model, is discretized using a hierarchic data structure. Results are presented for a Reynolds number Re - 75,000 computed on a high-performance parallel vector computer. State-of-the-art visualization techniques integrate the simulation results and the CAD model into a virtual reality environment. The VR environment allows also for an interactive analysis of thermal comfort criteria, being demonstrated for an indoor air flow simulation of an open-plan office. (C) 2002 Published by Elsevier Science B.V.
Spatial visualization skills are important in engineering graphics and computer-aided design courses, especially in solid modeling, which has gained popularity in recent years. Are basic mathematical skills a factor i...
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Spatial visualization skills are important in engineering graphics and computer-aided design courses, especially in solid modeling, which has gained popularity in recent years. Are basic mathematical skills a factor in improving spatial visualization abilities? Based on the need to develop these abilities, what mathematical courses should be set as prerequisites for engineering graphics courses? This paper presents a study of the relationship between basic mathematical skills and spatial visualization abilities. The Purdue Spatial visualization Test - Rotation was given to students taking engineering graphics courses. The results were compared with scores on a basic mathematical skills test, a placement test that all new students took when they applied to the college where this research was undertaken. Statistical analysis of the data revealed the effects of basic mathematical skills on spatial visualization abilities.
This review of medical imaging informaties is a survey of current developments in an exciting field. The focus is on informatics issues rather than traditional data processing and information systems, such as picture ...
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This review of medical imaging informaties is a survey of current developments in an exciting field. The focus is on informatics issues rather than traditional data processing and information systems, such as picture archiving and communications systems (PACS) and image processing and analysis systems. In this review, we address imaging informatics issues within the requirements of an informatics system defined by the American Medical Informatics Association. With these requirements as a framework, we review, in four sections: (1) Methods to present imaging and associated data without causing an overload, including image study summarization, content-based medical image retrieval, and natural language processing of text data. (2) data modeling techniques to represent clinical data with focus on an image data model, including general-purpose time-based multimedia data models, healthcare-specific data models, knowledge models, and problem-centric data models. (3) Methods to integrate medical data information from heterogeneous clinical data sources. Advances in centralized databases and mediated architectures are reviewed along with a discussion on our efforts at data integration based on peer-to-peer networking and shared file systems. (4) visualization schemas to present imaging and clinical data: the large volume of medical data presents a daunting challenge for an efficient visualization paradigm. In this section we review current multimedia visualization methods including temporal modeling, problem-specific data organization, including our problem-centric, context and user-specific visualization interface.
This paper presents an interactive global visualization technique for dense vector fields using levels of detail. We introduce a novel scheme which combines an error-controlled hierarchical approach and hardware accel...
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This paper presents an interactive global visualization technique for dense vector fields using levels of detail. We introduce a novel scheme which combines an error-controlled hierarchical approach and hardware acceleration to produce high resolution visualizations at interactive rates. Users can control the trade-off between computation time and image quality, producing visualizations amenable for situations ranging from high frame-rate previewing to accurate analysis. Use of hardware texture mapping allows the user to interactively zoom in and explore the data, and also to configure various texture parameters to change the look and feel of the visualization. We are able to achieve sub-second rates for dense LIC-like visualizations with resolutions in the order of a million pixels for data of similar dimensions.
Computerization in the medical field in Japan is being promoted by the advancement of network technology and system technology. In this paper, we describe a new medical-examination support system for a small and mediu...
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ISBN:
(纸本)1864671149
Computerization in the medical field in Japan is being promoted by the advancement of network technology and system technology. In this paper, we describe a new medical-examination support system for a small and medium-sized hospital. The feature of this system is the function of information integration and visualization for order data. This function is contributing as a medical-examination support function in a consultation room. The effectiveness of this system was verified by the questionnaire survey from doctors and the analysis of integration.
A simple and yet useful approach to visualize a variety of structures from sampled data is the Maximum Intensity Projection (MIP). Higher valued structures of interest project over occluding structures. This can make ...
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ISBN:
(纸本)0819444057
A simple and yet useful approach to visualize a variety of structures from sampled data is the Maximum Intensity Projection (MIP). Higher valued structures of interest project over occluding structures. This can make MIP images difficult to interpret due to the loss of depth information. Animating about the data is one key way to try to decipher such ambiguities. The challenge is that MIP is inherently expensive and thus high frame rates are difficult to achieve. Variations to the original MIP algorithm and classification can help to further alleviate ambiguities and provide improved image quality. Unfortunately, these improved techniques are even more expensive. In addition, they require substantial parameter searching and tweaking. As today's data sizes are increasingly getting larger, current methods only allow very limited interaction. We explore a view-dependent approach using concepts from image-based rendering. A novel multilayered image representation storing scalar information is computed at a view sample and then warped to the user's view. We present algorithms using OpenGL to quickly compute MIP and its variations using commodity off-the-shelf graphics hardware to achieve near interactive rates.
Applications in scientific visualization often involve extensive data sets, which represent scalar or vector valued functions resulting from experimental measurements. Ray Casting (RC) is a well-known approach for vis...
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ISBN:
(纸本)0819444057
Applications in scientific visualization often involve extensive data sets, which represent scalar or vector valued functions resulting from experimental measurements. Ray Casting (RC) is a well-known approach for visualizing a multi-dimensional volume data. It casts a large number of rays from the viewer into the volume and then computes the progressive attenuation along each ray in the volume. It is known that the ray-casting algorithm requires extensive computation time. In this study, we propose two techniques to speed up the ray-casting process. First, we derive an estimation of ray step sizes during its progressive re-sampling without invocating viewing transformation operations. Hence lengthy computations of trigonometric functions and matrix multiplications can be avoided. Furthermore, by exploring the ray coherence property, we propose a scan-line algorithm so that ray/volume intersections can be found efficiently. The proposed algorithm is implemented and compared with the conventional RC algorithm. Experimental results show that the proposed algorithm performs three to four times faster than the conventional RC algorithm.
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