Lagrangian-Eulerian advection of noise and dye textures for unsteady flow visualization

A new hybrid scheme, called Lagrangian-Eulerian advection (LEA), that combines the advantages of the Eulerian and Lagrangian frameworks is applied to the visualization of dense representations of time-dependent vector fields. The algorithm encodes the particles into a texture that is then advected. By treating every particle equally, we can handle texture advection and dye advection within a single framework. High temporal and spatial correlation is achieved through the blending of successive frames. A combination of particle and dye advection enables the simultaneous visualization of streamlines, particle paths and streak-lines. We demonstrate various experimental techniques on several physical flow fields. The simplicity of both the resulting data structures and the implementation suggest that LEA could become a useful component of any scientific visualization toolkit concerned with the display of unsteady flows.     

Interactive visualization of 3D seismic data: a volumetric method

The authors demonstrate the utility of examining seismic data with a volumetric scheme, whereby a synoptic view of the interior of the data volume is possible before conventional interpretation. High-amplitude seismic events, representing reflections from subterranean surfaces, are transformed to color pixels, and the resulting 3-D images reveal the structure of the geological layers. Such morphological features as hills, valleys, and faults are apparent indicating that the approach could prove useful for identifying potential oil reservoirs. The authors implement the technique on a personal computer to produce displays of similar quality, but they find that the construction of the 3-D images is too slow for reasonable interactivity. However, with the addition of a parallel-processing accelerator, a personal-computer-based workstation would be feasible for this kind of 3-D visualization and interpretation     

基于纹理的三维超声实时体绘制

三维纹理的体绘制算法由于其利用显卡加速渲染、硬件实现三线性插值和不丢失图像的纹理特性3大优点，尤其适合医学超声数据的实时三维可视化。显示大量多边形切片（slice polygon）是当前影响三维纹理体绘制渲染实时性的重要因素。为了克服常用的参数化算法在快速生成大量多边形切片时性能不佳的缺点，提出了的空间活动边表的方法，充分利用各个多边形切片之间的空间相关性实现增量计算，明显提高了计算速度。     

动态图的实时三维可视化的稳定性算法

提出动态图的实时三维可视化及其稳定性的问题。讨论在图的实时重画中兼顾动态稳定性和美观性的平衡策略。在三维静态美观布局算法的基础上，给出了动态图的若干实时三维可视化的稳定性算法，并分析了这些算法的时间性能和适用范围。算法已应用在若干可视化编程环境。     

3D flow features visualization via fuzzy clustering

A key approach to visualizing a flow field is to emphasize regions with significant behavior. However, it is difficult to give concrete criteria for classifying feature regions. In this paper, we use a novel framework in which fuzzy sets are used to determine flow features: Fuzzy relationships assess structural properties of features. A fuzzy c-means-like clustering algorithm is used to evaluate the importance of each voxel. Our approach can be readily modified with new fuzzy relationships describing other features of interest to users. We use a multi-resolution approach which displays structural features in greater detail, and represents the background by coarse-grained information. Experiments on synthetic and real datasets show that our framework can highlight significant aspects of the whole flow while avoiding occlusion and clutter. Interactive performance is achieved via a GPU implementation.     

基于Web的三维实时井眼轨迹可视化方法研究与实现

针对基于Web的实时三维可视化应用需求,结合邻近井段的结构形状、变化规律,改进了贝塞尔曲线拟合算法,提高了测斜数据处理速率和曲化度,并采用Away3D技术实现轨迹的三维展示。应用结果表明,轨迹绘制细腻流畅,系统具备良好的实时性。     

实时界定雷达电磁互扰区域的三维可视化方法

为了便于多方位、多角度观察和分析舰艇编队中雷达电磁互扰的区域, 利用等值面的分界特性, 通过使用能流密度和干扰余量来表现舰艇编队中雷达电磁互扰的程度, 提出使用递进式栅格采样的极值八叉树快速重构等值面的方法, 还提出使用等值面差别显示的方法建立实时交互的三维显示图和俯视、前视、侧视的动态切面图, 来动态显示舰艇编队雷达电磁互扰的仿真结果。通过对6艘舰艇共16部单脉冲雷达的仿真, 实验结果表明该方法可行、有效。该方法还可以应用到其他电磁环境的实时三维可视化中, 也可以应用在研究和预防无人机被雷达电磁干扰的三维仿真中。     

Tensor3D: A computer graphics program to simulate 3D real-time deformation and visualization of geometric bodies

Tensor3D is a geometric modeling program with the capacity to simulate and visualize in real-time the deformation, specified through a tensor matrix and applied to triangulated models representing geological bodies. 3D visualization allows the study of deformational processes that are traditionally conducted in 2D, such as simple and pure shears. Besides geometric objects that are immediately available in the program window, the program can read other models from disk, thus being able to import objects created with different open-source or proprietary programs. A strain ellipsoid and a bounding box are simultaneously shown and instantly deformed with the main object. The principal axes of strain are visualized as well to provide graphical information about the orientation of the tensor's normal components. The deformed models can also be saved, retrieved later and deformed again, in order to study different steps of progressive strain, or to make this data available to other programs. The shape of stress ellipsoids and the corresponding Mohr circles defined by any stress tensor can also be represented. The application was written using the Visualization ToolKit, a powerful scientific visualization library in the public domain. This development choice, allied to the use of the Tcl/Tk programming language, which is independent on the host computational platform, makes the program a useful tool for the study of geometric deformations directly in three dimensions in teaching as well as research activities.     

Importance sampling for volumetric illumination of flames

Physically based rendering of scenes with volumetric illumination of flames remains a challenging problem due to the complexity of their heterogeneous radiative properties. Current bidirectional importance sampling strategies have been focusing on emissive light sources without anisotropic extinction. In this paper, we present an efficient importance sampling method for volumetric light sources with anisotropic extinction. According to the radiative properties of flames, we separate the computation of anisotropic extinction from the evaluation of illumination inside flames and utilize cluster-based hierarchies to rapidly estimate them. To exploit the coherence of radiative voxels, we also propose a new similarity metric to aggregate voxels into clusters. For each pixel to be shaded, we use these clusters to rapidly approximate the importance function of voxels, and draw final illumination samples from clusters. Our results show that this approach substantially reduces the variance of images when rendering scenes with flames.     

Influence of georeference for saturated excess overland flow modelling using 3D volumetric soft geo-objects

Existing 2D data structures are often insufficient for analysing the dynamism of saturation excess overland flow (SEOF) within a basin. Moreover, all stream networks and soil surface structures in GIS must be preserved within appropriate projection plane fitting techniques known as georeferencing. Inclusion of 3D volumetric structure of the current soft geo-objects simulation model would offer a substantial effort towards representing 3D soft geo-objects of SEOF dynamically within a basin by visualising saturated flow and overland flow volume. This research attempts to visualise the influence of a georeference system towards the dynamism of overland flow coverage and total overland flow volume generated from the SEOF process using VSG data structure. The data structure is driven by Green-Ampt methods and the Topographic Wetness Index (TWI). VSGs are analysed by focusing on spatial object preservation techniques of the conformal-based Malaysian Rectified Skew Orthomorphic (MRSO) and the equidistant-based Cassini-Soldner projection plane under the existing geodetic Malaysian Revised Triangulation 1948 (MRT48) and the newly implemented Geocentric Datum for Malaysia (GDM2000) datum. The simulated result visualises deformation of SEOF coverage under different georeference systems via its projection planes, which delineate dissimilar computation of SEOF areas and overland flow volumes. The integration of Georeference, 3D GIS and the saturation excess mechanism provides unifying evidence towards successful landslide and flood disaster management through envisioning the streamflow generating process (mainly SEOF) in a 3D environment.     

Hole filling in 3D volumetric objects

The construction of hole filling (or hole segmentation) method for 3D volumetric images is a new challenging issue in computer science. It needs a geometrical approach since from a topological point of view 3D holes (tunnels) are not well-delimited subsets of three dimensional space. In this paper, the authors propose an original, efficient, flexible algorithm of hole filling for volumetric objects. The algorithm has been tested on artificial objects and very complicated crack propagation tomography images. The qualitative results, quantitative results and features of proposed approach are presented in the paper. According to our knowledge it is the first algorithm of hole filling for volumetric objects.     

A heterogeneous computing system for coupling 3D endomicroscopy with volume rendering in real-time image visualization

Modern microscopic volumetric imaging processes lack capturing flexibility and are inconvenient to operate. Additionally, the quality of acquired data could not be assessed immediately during imaging due to the lack of a coherent real-time visualization system. Thus, to eliminate the requisition of close user supervision while providing real-time 3D visualization alongside imaging, we propose and describe an innovative approach to integrate imaging and visualization into a single pipeline called an online incrementally accumulated rendering system. This system is composed of an electronic controller for progressive acquisition, a memory allocator for memory isolation, an efficient memory organization scheme, a compositing scheme to render accumulated datasets, and accumulative frame buffers for displaying non-conflicting outputs. We implement this design using a laser scanning confocal endomicroscope, interfaced with an FPGA prototyping board through a custom hardware circuit. Empirical results from practical implementations deployed in a cancer research center are presented in this paper.     

Web-based visualization of 3D geospatial data using Java3D

Spatial database servers allow for the storage and access of 3D geospatial data using open geospatial consortium standards. The Geospatial Database Online Visualization Environment (GeoDOVE) is a prototype 3D Web-based geographic information system that demonstrates how Java3D can reduce bandwidth and allow direct connectivity to spatially enabled database systems. We've developed GeoDOVE, a Java3D-based prototype system that retrieves geospatial data from conventional spatial database servers, allows modification of the visualization during runtime, and lets users remotely modify attributes using the structured query language (SQL).     

Collaborative 3D visualization with CSpray

CSpray lets small groups of geographically distributed scientists share data and interactively create visualizations. It features different information-sharing levels, a session manager, and 3D visualization aids     

3D stereo interactive medical visualization

Our interactive, 3D stereo display helps guide clinicians during endovascular procedures, such as intraoperative needle insertion and stent placement relative to the target organs. We describe a new method of guiding endovascular procedures using interactive 3D stereo visualizations. We use as an example the transjugular intrahepatic portosystemic shunt (TIPS) procedure. Our goal is to increase the speed and safety of endovascular procedures by providing the interventionalist with 3D information as the operation proceeds. Our goal is to provide 3D image guidance of the TIPS procedure so that the interventionalist can readily adjust the needle position and trajectory to reach the target on the first pass. We propose a 3D stereo display of the interventionalist's needle and target vessels. We also add interactivity via head tracking so that the interventionalist gains a better 3D sense of the relationship between the target vessels and the needle during needle advancement.     

Interactive 3D visualization of optical phenomena

Each year at colleges and universities nationwide, some 10,000 students take a course on optics, typically through a physics department. The method of instruction has changed very little in the past 40 years, and many of the textbook illustrations have remained essentially the same during this time. In particular, the illustrations rely heavily on line drawings and 2D graphs. Certain key concepts in optics possess fundamentally 3D aspects, which instructors typically demonstrate in a classroom laboratory. Currently, several computer-assisted instructional modules support teaching optics by visualizing optical phenomena. We created interactive 3D graphical modules for visualizing optical phenomena by applying 3D visualization techniques to instructional courseware     

三维可视化概念层次模型

通过建立平面、三棱柱、六面体和箭头等通用体素,并将文字、图像、定律等相关信息映射到各个通用体素的表面,表示概念设计过程中用到的功能、分功能、基本功能和原理解等概念,有效地扩展了虚拟现实建模语言(VRML)描述三维概念层次模型的能力,并以雷达为例,直观地建立概念设计过程中的三维层次模型,以辅助产品的概念设计过程。