Head detection is an important, but difficult task, if no restrictions such as static illumination, frontal face appearance or uniform background can be assumed. We present a system that is able to perform head detect...
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In this case study, we explore techniques for the purpose of visualizing isolated flow structures in time-dependent data. Our primary industrial application is the visualization of the vortex rope, a rotating helical ...
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In this case study, we explore techniques for the purpose of visualizing isolated flow structures in time-dependent data. Our primary industrial application is the visualization of the vortex rope, a rotating helical structure which builds up in the draft tube of a water turbine. The vortex rope can be characterized by high values of normalized helicity, which is a scalar field derived from the given CFD velocity data. In two related applications, the goal is to visualize the cavitation regions near the runner blades of a Kaplan turbine and a water pump, respectively. Again, the flow structure of interest can be defined by a scalar field, namely by low pressure values. We propose a particle seeding scheme based on quasi-random numbers, which minimizes visual artifacts such as clusters or patterns. By constraining the visualization to a region of interest, occlusion problems are reduced and storage efficiency is gained.
Surface models used in 3D computergraphics are generally constructed with highly complex and large-volumed polygonal patches. These complex models can provide a convincing level of realism, but cause many problems du...
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Surface models used in 3D computergraphics are generally constructed with highly complex and large-volumed polygonal patches. These complex models can provide a convincing level of realism, but cause many problems due to the data redundancy. Therefore, a method is needed that can effectively decrease the large dataset with shape preservation of the original model. We present an edge cost function that reflects well the local geometric features of surface and implement a surface simplification algorithm based on iterative edge contraction by merging. The merging-based contraction scheme is more efficient in memory usage and useful in practical applications, requiring real-time data transmission, especially in network environment. The experimental results show that the proposed algorithm results in higher quality approximations of original models with excellent shape preservation than existing approaches.
To reconstruct the shape of objects from incomplete point sets or noisy images, robust and accurate reconstruction methods are required. This paper presents a physics-based approach for automatically reconstructing th...
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The current state of the art in visualization research places a strong emphasis on different techniques to derive insight from disparate types of data. However, little work has investigated the visualization process i...
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The current state of the art in visualization research places a strong emphasis on different techniques to derive insight from disparate types of data. However, little work has investigated the visualization process itself. The information content of the visualization process-the results, history, and relationships between those results-is addressed by this work. A characterization of the visualization process is discussed, leading to a general model of the visualization exploration process. The model, based upon a new parameter derivation calculus, can be used for automated reporting, analysis, or visualized directly. An XML-based language for expressing visualization sessions using the model is also described. These sessions can then be shared and reused by collaborators. The model, along with the XML representation, provides an effective means to utilize the information within the visualization process to further data exploration.
In this paper is described how computer supported cooperative work can be used to enhance project development memory, focusing on software development. The collaboration model that is presented is based upon the conce...
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In this paper is described how computer supported cooperative work can be used to enhance project development memory, focusing on software development. The collaboration model that is presented is based upon the concepts of communication, coordination and cooperation. Each of these concepts is analyzed regarding software specification. The paper presents some examples of systems that seek to capture and refine group ideas through the process of argumentation. The paper also shows how the building of project memory can facilitate the recovery of the context and the reasoning that led to the taking of project decisions.
This paper describes a run-time specialization system for the Java language. One of the main difficulties of supporting the full Java language resides in a sound yet effective management of references to objects. This...
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This paper describes a run-time specialization system for the Java language. One of the main difficulties of supporting the full Java language resides in a sound yet effective management of references to objects. This is because the specialization process may share references with the running application that executes the residual code, and because side-effects through those references by the specialization process could easily break the semantics of the running application. To cope with these difficulties, we elaborate requirements that ensure sound run-time specialization. Based on them, we design and implement a run-time specialization system for the Java language, which exhibits, for instance, approximately 20-25% speed-up factor for a ray-tracing application.
Interactive visualization of large digital elevation models is of continuing interest in scientific visualization, GIS, and virtual reality applications. Taking advantage of the regular structure of grid digital eleva...
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Interactive visualization of large digital elevation models is of continuing interest in scientific visualization, GIS, and virtual reality applications. Taking advantage of the regular structure of grid digital elevation models, efficient hierarchical multiresolution triangulation and adaptive level-of-detail (LOD) rendering algorithms have been developed for interactive terrain visualization. Despite the higher triangle count, these approaches generally outperform mesh simplification methods that produce irregular triangulated network (TIN) based LOD representations. In this project we combine the advantage of a TIN based mesh simplification preprocess with high-performance quadtree based LOD triangulation and rendering at run-time. This approach, called QuadTIN, generates an efficient quadtree triangulation hierarchy over any irregular point set that may originate from irregular terrain sampling or from reducing oversampling in high-resolution grid digital elevation models.
This paper describes a computerized simulation system for minimally invasive vascular interventions using Virtual-Reality (VR) based technology. A virtual human patient is constructed using the Visible Human Data (VHD...
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This paper describes a computerized simulation system for minimally invasive vascular interventions using Virtual-Reality (VR) based technology. A virtual human patient is constructed using the Visible Human Data (VHD). A knowledge-based human vascular network is developed to describe human vascular anatomy with diseased lesions for different interventional applications. A potential field method is applied to model the interaction between the blood vessels and vascular catheterization devices. A haptic interface is integrated with the computer simulation system to provide tactile sensations to the user during the simulated catheterization procedures. The system can be used for physician training and for pre-treatment planning of interventional vascular procedures.
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