Scientific Visualization Applications Research Articles

CAVE and fishtank virtual-reality displays: a qualitative and quantitative comparison

We present the results from a qualitative and quantitative user study comparing fishtank virtual-reality (VR) and CAVE displays. The results of the qualitative study show that users preferred the fishtank VR display to the CAVE system for our scientific visualization application because of perceived higher resolution, brightness and crispness of imagery, and comfort of use. The results of the quantitative study show that users performed an abstract visual search task significantly more quickly and more accurately on the fishtank VR display system than in the CAVE. The same study also showed that visual context had no significant effect on task performance for either of the platforms. We suggest that fishtank VR displays are more effective than CAVEs for applications in which the task occurs outside the user's reference frame, the user views and manipulates the virtual world from the outside in, and the size of the virtual object that the user interacts with is smaller than the user's body and fits into the fishtank VR display. The results of both studies support this proposition.

A105 GADGET/FV:ビジュアルフローデータマイニングのためのユーザ支援環境

Scientific visualization is widely used for the analysis of datasets obtained from measurements and numerical simulations. However, scientists and engineers are not always visualization experts who are familiar with how to map their numerical data to proper graphical primitives to yield optimal visualization. Therefore, we have built on modular visualization environments (MVEs) to develop a design support system, called GADGET, for scientific visualization applications. In this paper, we attempt to reexamine specifications for design directives to make the GADGET system tailored to visual flow data mining.

Extending the SAND Spatial Database System for the Visualization of Three‐Dimensional Scientific Data

The three‐dimensional extension of the SAND (Spatial and Nonspatial Data) spatial database system is described as is its use for data found in scientific visualization applications. The focus is on surface data. Some of the principal operations supported by SAND involve locating spatial objects in the order of their distance from other spatial objects in an incremental manner so that the number of objects that are needed is not known a priori. These techniques are shown to be useful in enabling users to visualize the results of certain proximity queries without having to execute algorithms to completion as is the case when performing a nearest‐neighbor query where a Voronoi diagram (i.e., Thiessen polygon) would be computed as a preprocessing step before any attempt to respond to the query could be made. This is achieved by making use of operations such as the spatial join and the distance semijoin. Examples of the utility of such operations is demonstrated in the context of posing meteorological queries to a spatial database with a visualization component.

Interactive parallel visualization of large particle datasets

This paper presents a new interactive parallel visualization method for large particle datasets by directly rendering individual particles based on a parallel rendering cluster. A frame rate of 9 frames-per-second is achieved for 256 3 particles using 7 render nodes and a display node. This provides real time interaction and interactive exploration of large datasets, which has been a challenge for scientific visualization and other real time data mining applications. A dynamic data distribution technique is designed for highlighting a subset of the particle volume. It maintains load balance of the system and minimizes network traffic by reconfiguring the rendering chain. Experiments show that on a given subset, interactive manipulation of the subset usually requires less than 3% of the particles inside the subset to be redistributed among all render nodes. The method can be easily extended to other large datasets such as hydrodynamic turbulence, fluid dynamics, and so on.

CoDIMS: an adaptable middleware system for scientific visualization in Grids

AbstractIn this paper we propose a middleware infrastructure adapted for supporting scientific visualization applications over a Grid environment. We instantiate a middleware system from CoDIMS, which is an environment for the generation of configurable data integration middleware systems. CoDIMS adaptive architecture is based on the integration of special components managed by a control module that executes users workflows. We exemplify our proposal with a middleware system generated for computing particles' trajectories within the constraints imposed by a Grid environment. Copyright © 2004 John Wiley & Sons, Ltd.

Nonlinear projection: using deformations in 3D viewing

We present techniques for achieving nonlinear projections and distortions and use these techniques to generate distorted panorama and fish-eye virtual views, environmental texture mapping, and other special visual effects. Past experiments on nonlinear distortions primarily focused on 2D distortion or abstract mathematical camera models for noninteractive ray tracing. We developed and tested an experimental system based on these methods that lets one navigate a 3D virtual world with nonlinear perspective projection in real time. Our methods have many applications in conceptual design, computer games, and scientific visualization.

A spectrally based framework for realistic image synthesis

Realistic image synthesis provides principles and techniques for creating realistic imagery based on models of real-world objects and behaviors. It has widespread applications in 3D design, computer animation, and scientific visualization. While it is common to describe light and objects in terms of colors, this approach is not sufficiently accurate and cannot render many spectral phenomena such as interference and diffraction. Many researchers have explored spectral rendering and proposed several methods for spectral representation, but none satisfy all representation criteria such as accuracy, compactness and efficiency. Furthermore, previous studies have focused on distinct behaviors of natural phenomena but few on their commonality and generality, and it is difficult to combine existing algorithms to simulate complex processes. This thesis proposes solutions to these problems within a spectrum-based rendering framework. The pipeline begins by loading spectra from a database to specify light sources and objects, then generates a spectral image based on local and global illumination models, projects the spectral image into a CIE image, and finally converts the CIE image into an RGB image for display or a CIELab image for evaluation. In spite of omitting the light phase information, it is shown that this approach suffices to generate all optical effects important for realistic image synthesis. As components of the new framework, a heuristic method is proposed for deriving spectra from colors and an error metric is provided for evaluating synthesized images. The new spectral representation proposed in this thesis is called the composite model. Its key point is to decompose any spectrum into a smooth background and a collection of spikes. The smooth part can be represented by Fourier coefficients and a spike by its location and height. A re-sampling technique is proposed to improve performance. Based upon the characteristics of human perception, the sufficiency of a low-dimensional representation is shown analytically. This model improves upon existing methods with aspect to accuracy, compactness and efficiency, and offers an effective vehicle for rendering optical effects involving spiky spectra. Using the proposed framework and composite spectral model, this thesis develops new illumination models for rendering a number of optical effects including dispersion, interference, diffraction, fluorescence, and volume absorption. The rendered images closely correspond to their real-world counterparts. Overall, this thesis improves realistic image synthesis by expanding its rendering capabilities. It may serve as a basis for a more sophisticated rendering environment for high-quality computer image generation.

A framework for interactive responsive animation

The availability of high-performance 3D workstations has increased the range of application for interactive real-time animation. In these applications the user can directly interact with the objects in the animation and direct the evolution of their motion, rather than simply watching a pre-computed animation sequence. Interactive real-time animation has fast-growing applications in virtual reality, scientific visualization, medical training and distant learning. Traditional approaches to computer animation have been based on the animator having complete control over all aspects of the motion. In interactive animation the user can interact with any of the objects, which changes the current motion path or behaviour in real time. The objects in the animation must be capable of reacting to the user's actions and not simply replay a canned motion sequence. This paper presents a framework for interactive animation that allows the animator to specify the reactions of objects to events generated by other objects and the user. This framework is based on the concept of relations that describe how an object reacts to the influence of a dynamic environment. Each relation specifies one motion primitive triggered by either its enabling condition or the state of the environment. A collection of the relations is structured through several hierarchical layers to produce responsive behaviours and their variations. This framework is illustrated by several room-based dancing examples that are modelled by relations. Copyright © 2000 John Wiley & Sons, Ltd.

An object-oriented architecture for applications of scientific visualization and mathematical modeling

Issues of the general architecture design for integrated applications of mathematical modeling and scientific visualization are considered. In line with the object-oriented methodologies of Bailin and Booch, a novel model for a visualization scene is described. The scene is a composition of interrelated, typed scientific data and algorithms. A systematic approach to developing applications based on the model is presented. Theoretical analysis is illustrated by various examples related to geometric modeling, numerical solution of ordinary differential equations, visualization, and rendering.

A framework for interactive responsive animation

The availability of high-performance 3D workstations has increased the range of application for interactive real-time animation. In these applications the user can directly interact with the objects in the animation and direct the evolution of their motion, rather than simply watching a pre-computed animation sequence. Interactive real-time animation has fast-growing applications in virtual reality, scientific visualization, medical training and distant learning. Traditional approaches to computer animation have been based on the animator having complete control over all aspects of the motion. In interactive animation the user can interact with any of the objects, which changes the current motion path or behaviour in real time. The objects in the animation must be capable of reacting to the user's actions and not simply replay a canned motion sequence. This paper presents a framework for interactive animation that allows the animator to specify the reactions of objects to events generated by other objects and the user. This framework is based on the concept of relations that describe how an object reacts to the influence of a dynamic environment. Each relation specifies one motion primitive triggered by either its enabling condition or the state of the environment. A collection of the relations is structured through several hierarchical layers to produce responsive behaviours and their variations. This framework is illustrated by several room-based dancing examples that are modelled by relations. Copyright © 2000 John Wiley & Sons, Ltd.

Hardware architecture for voxelization-based volume rendering of unstructured grids

Interactive volume visualization of unstructured grid data is a much sought after, but as yet elusive, goal in many scientific visualization applications. We present an architecture that can possibly bring this goal within reach. In this architecture we combine the recently identified method of using texture mapping for volume rendering [R.A. Crawfis, N. Max, Texture Splats for 3D Scalar and Vector Field Visualization, Proceedings of Visualization '93, San Jose 1993, pp. 261–266; B. Cabral, N. Cam, J. Foran, Accelerated volume rendering and tomographic reconstruction using texture mapping hardware, Proceedings of the ACM Symposium on Volume Visualization '94 1994, pp. 91–98.] with anti-aliased voxelization. We show how the proposed architecture can be implemented with simple extensions to existing high-end graphics systems, using the SGI Reality Engine (RE) as an example. The architecture has the advantage of providing both direct volume rendering and polygon based rendering at high performance levels on the same hardware platform. We present some simulation results that demonstrate the validity of our architecture.

Adaptive real-time level-of-detail based rendering for polygonal models

We present an algorithm for performing adaptive real-time level-of-detail-based rendering for triangulated polygonal models. The simplifications are dependent on viewing direction, lighting, and visibility and are performed by taking advantage of image-space, object-space, and frame-to-frame coherences. In contrast to the traditional approaches of precomputing a fixed number of level-of-detail representations for a given object, our approach involves statically generating a continuous level-of-detail representation for the object. This representation is then used at run time to guide the selection of appropriate triangles for display. The list of displayed triangles is updated incrementally from one frame to the next. Our approach is more effective than the current level-of-detail-based rendering approaches for most scientific visualization applications, where there are a limited number of highly complex objects that stay relatively close to the viewer. Our approach is applicable for scalar (such as distance from the viewer) as well as vector (such as normal direction) attributes.

Improving End System Performance for Multimedia Applicationsover High Bandwidth Networks

Digital video services, scientific visualization and other multimedia applications require delivery of high network throughput to end user applications. In this paper we identify bottlenecks in the data path between high-speed networks and applications. Using performance of multimedia applications as a metric, the effectiveness of solutions to reduce network, operating system, and user bottlenecks is explored experimentally.

PHYSICS BASED GEOMETRIC DESIGN

Geometric modeling has proved to be crucial to computer graphics and computer aided geometric design (CAGD). During the past several decades, numerous geometric formulations have been proposed for a large variety of geometric modeling applications. In this paper, we survey the diversity of shape representations ranging from the primitive polynomial to the sophisticated Non-Uniform Rational B-Spline (NURBS). We demonstrate that, among various geometric representations, NURBS have become an industrial standard primarily because of their many superior properties. By reviewing commonly used design paradigms such as interpolation, approximation, interactive modification and variational optimization, we can also show that these conventional geometric design techniques are generally awkward when designers are confronted by complex, real-world objects. This is primarily because they only allow free-form primitives such as NURBS to be indirectly manipulated through numerous degrees of freedom (DOFs). To overcome the disadvantages of this indirect process, we summarize the prior work of physics-based modeling and review dynamic NURBS (D-NURBS) as a physics-based generalization of geometric NURBS for shape design. D-NURBS can unify the features of the industry-standard NURBS geometry with the many demonstrated conveniences of interaction within the new physics-based design framework. We demonstrate that D-NURBS cannot only serve as a basis for the future research of physics-based geometric design but also become readily appropriate for a large variety of important applications in graphics, vision, and scientific visualization.

Motion without movement

We describe a technique for displaying patterns that appear to move continuously without changing their positions. The method uses a quadrature pair of oriented filters to vary the local phase, giving the sensation of motion. We have used this technique in various computer graphic and scientific visualization applications.

Scientific Visualization: What's Beyond the Vision?

The author presents an overview of developments in scientific visualization. This paper focuses on the practical applications of scientific visualization being developed as a result of advances in computer technology. Recent progress in computer graphics and supercomputing architectures is discussed.

Rational hypersurface display

Algorithms are presented for polygonalizing implicitly defined, quadric and cubic hypersurfaces in n ≥ 3 dimensional space and furthermore displaying their projections in 3D. The method relies on initially constructing the rational parametric equations of the implicitly defined hypersurfaces, and then polygonalizing these hypersurfaces by an adaptive generalized curvature dependent scheme. The number of hyperpolygons used are optimal, in that they are the order of the minimum number required for a smooth Gouraud like shading of the hypersurfaces. Such hypersurface projection displays should prove useful in scientific visualization applications. The curvature dependent polygonal meshes produced, should also prove very useful in finite difference and finite element analysis programs for multi-dimensional domains.

The application visualization system: a computational environment for scientific visualization

A software system for developing interactive scientific visualization applications quickly, with a minimum of programming effort, is described. This application visualization system (AVS) is an application framework targeted at scientists and engineers. The goal of the system is to make applications that combine interactive graphics and high computational requirements easier to develop for both programmers and nonprogrammers. AVS is designed around the concept of software building blocks, or modules, which can be interconnected to form visualization applications. AVS allows flow networks of existing modules to be constructed using a direct-manipulation user interface, and it automatically generates a simple user interface to each module. >