Ilmi Yoon

Webs on the Web (WOW): 3D visualization of ecological networks on the WWW for collaborative research and education

This paper describes information technology being developed to improve the quality, sophistication, accessibility, and pedagogical simplicity of ecological network data, analysis, and visualization. We present designs for a WWW demonstration/prototype web site that provides database, analysis, and visualization tools for research and education related to food web research. Our early experience with a prototype 3D ecological network visualization guides our design of a more flexible architecture design. 3D visualization algorithms include variable node and link sizes, placements according to node connectivity and tropic levels, and visualization of other node and link properties in food web data. The flexible architecture includes an XML application design, FoodWebML, and pipelining of computational components. Based on users’ choices of data and visualization options, the WWW prototype site will connect to an XML database (Xindice) and return the visualization in VRML format for browsing and further interactions.

Web-based remote rendering with image-based rendering acceleration and compression

Recent advances in Internet and computer graphics stimulate intensive use and development of 3D graphics on the World Wide Web. To increase efficiency of systems using 3D graphics on the web, the presented method utilizes previously rendered and transmitted images to accelerate the rendering and compression of new synthetic scene images. The algorithm employs ray casting and epipolar constraints to exploit spatial and temporal coherence between the current and previously rendered images. The reprojection of color and visibility data accelerates the computation of new images. The rendering method intrinsically computes a residual image, based on a user specified error tolerance that balances image quality against computation time and bandwidth. Encoding and decoding uses the same algorithm, so the transmitted residual image consists only of significant data without addresses or offsets. We measure rendering speed‐ups of four to seven without visible degradation. Compression ratios per frame are a factor of two to ten better than MPEG2 in our test cases. There is no transmission of 3D scene data to delay the first image. The efficiency of the server and client generally increases with scene complexity or data size since the rendering time is predominantly a function of image size. This approach is attractive for remote rendering applications such as web‐based scientific visualization where a client system may be a relatively low‐performance machine and limited network bandwidth makes transmission of large 3D data impractical.

Interactive, Internet Delivery of Visualization via Structured Prerendered Multiresolution Imagery

We present a novel approach for latency-tolerant delivery of visualization and rendering results, where client-side frame rate display performance is independent of source data set size, image size, visualization technique, or rendering complexity. Our approach delivers prerendered multiresolution images to a remote user as they navigate through different viewpoints, visualization parameters, or rendering parameters. We employ demand-driven tiled multiresolution image streaming and prefetching to efficiently utilize available bandwidth while providing the maximum resolution a user can perceive from a given viewpoint. Since image data is the only input to our system, our approach is generally applicable to all visualization and graphics rendering applications capable of generating v in an ordered fashion. In our implementation, a normal Web server provides on-demand images to a remote custom client application, which uses client-pull to obtain and cache only those images required to fulfill the interaction needs. The main contributions of this work are 1) an architecture for latency-tolerant remote delivery of precomputed imagery suitable for use with any visualization or rendering application capable of producing images in an ordered fashion; and 2) a performance study showing the impact of diverse network environments and different tunable system parameters on end-to-end system performance in terms of deliverable frames per second.

Compression of computer graphics images with image-based rendering

We present a new compression algorithm for synthetic images that produces high compression rates by utilizing depth and color information from previously rendered images. Images predicted from prior images are combined with a residual image that may be transmitting from a remote location, to generate new images. The image-based rendering technique provides accurate motion prediction and accelerates rendering at the same time by exploiting temporal coherence. The motion prediction is computed and evaluated in image- order, pixel by pixel, producing residual images that are sparse and do not require address or index data. The system yields a compression ratio improvement of a factor of 4 - 10 over MPEG, in many cases. This approach is attractive for remote rendering applications where a client system may be a relatively low-performance machine and limited network bandwidth makes transmission of large 3D data impractical. The efficiency of the server generally increases with scene complexity or data size since the rendering time is predominantly a function of image size. This technique is also applicable to archiving animation.

Parts, image, and sketch based 3D modeling method

Despite their many benefits, challenges exist in the creation of 3D models, particularly for individual not currently skilled with 3D modeling software. To address this, we explore the creation of 3D modeling software for non-domain experts that uses a hierarchical parts database of generic 3D models, and deforms models into specific related target objects using image guided 3D model morphing. A human-in-the-loop sketching interface supports image registration and constrains our geometrical transformation to support real time morphing of generic models into accurate representations of new objects for which users wish a 3D model. Applying the application to the study of insects in biology, we find that the application supports the creation of realistic 3D models, and that the application is of value to educators and researchers in entomology.

Iterative design and development of the ‘World of Balance’ game: From ecosystem education to scientific discovery

Advances in computer science are continuing to help expand a new subfield of ecology based on computational analyses of complex ecological networks where the nonlinear dynamics of many interacting species can be more realistically modeled and understood. Research has recently elucidated how the network structure of feeding relationships both generally stabilize complex ecosystems and also specifically predict effects of experimentally removing species. Still, further research is inhibited by the exponential increase of parameter space with the number of nonlinearly interacting species. Such increases prevent more thorough exploration and understanding of complex ecosystems. Here, we describe how intelligent interfaces for multiplayer games help researchers surpass these limitations. Our applications including a multiplayer online game, “World of Balance,” educates players about interdependence and non-linear population dynamics among species within ecosystems while helping to explore critically important parameter space in a scientifically productive manner. Our evaluation tests found that benefits of playing World of Balance on knowledge gain and learning significantly surpassed the benefits of reading scientific articles among undergraduates. Such work efficiently leverages multiple resources to expand education and research potential within critically important areas of ecology and sustainability science.

Smooth scene transition for virtual tour on the World Wide Web

This paper presents a robust image registration technique for creating smooth scene transitions for a Web-based virtual tour system. Easy and effective virtual tour (EEVT). EEVT has advantages over traditional geometry-based 3D rendering approach in that it does not require labor intensive 3D modeling process or high bandwidth for realistic virtual tour yet provides a virtual tour with free navigation and immersive experience through the WWW. EEVT constructs virtual tour from a set of images. It uses several snap shots of conventional photos without special tools, builds a simple 3D space within each photo using the spidery mesh technique, and expands the virtual spaces by connecting each space together. The connection between images is achieved by image registration, which finds correspondences automatically and estimates transformations. The image registration process is crucial for virtual tour applications in order to compose smooth transitional scenes between two views so that virtual tourists perceive continuous scenes during navigation. Our registration method uses a parametric approach and it includes the following key features for robust and accurate computation: 1) coarse-to-fine hierarchical estimation; 2) fast computation based on image feature-correspondences; 3) FFT-based global matching, 4) automatic outlier removal by RANSAC. The expanded virtual space creates a sense of navigational freedom for virtual tourists with less distorted viewing.

Image-assisted visualizations over networks

The World Wide Web is incorporating recent advances in Internet technology and 3-D graphics, promoting the spread of visu- alization over networks. To increase the efficiency of web-based 3-D graphics systems including scientific visualizations, we present a method that utilizes previously rendered and transmitted images in- stead of transmitting 3-D models to the client. Our image-based rendering and compression (IBRAC) method exploits spatial and temporal coherence between new and previously rendered syn- thetic images. Reprojecting color and visibility data accelerates the computation of new images, while reprojecting the surface orienta- tion eliminates inconsistencies in shading and lighting changes that plague other image-based rendering methods. We also present a new image data structure called an isomap, containing classification-interval data that enables a remote user to interac- tively classify volume data without loading the 3-D dataset. Our ap- proach produces rendering speedups of seven and more without visible degradation, and compression ratios are a factor of 2 to 10 times better than MPEG2 in our test cases. The approach is best suited for remote rendering applications, where the client has limited rendering resources and network bandwidth, including wireless or palm computing applications.

Interactive, internet delivery of scientific visualization via structured, prerendered imagery

In this paper, we explore leveraging industry-standard media formats to effectively deliver interactive, 3D scientific visualization to a remote viewer. Our work is motivated by the need for remote visualization of time-varying, 3D data produced by scientific simulations or experiments while taking several practical factors into account, including: maximizing ease of use from the users perspective, maximizing reuse of image frames, and taking advantage of existing software infrastructure wherever possible. Visualization or graphics applications first generate images at some number of view orientations for 3D scenes and temporal locations for time-varying scenes. We then encode the resulting imagery into one of two industry-standard formats: QuickTime VR Object Movies or a combination of HTML and JavaScript code implementing the client-side navigator. Using an industry-standard QuickTime player or web browser, remote users may freely navigate through the pre-rendered images of time-varying, 3D visualization output. Since the only inputs consist of image data, a viewpoint and time stamps, our approach is generally applicable to all visualization and graphics rendering applications capable of generating image files in an ordered fashion. Our design is a form of latency-tolerant remote visualization infrastructure where processing time for visualization, rendering and content delivery is effectively decoupled from interactive exploration. Our approach trades off increased interactivity, reduced load and effective reuse of coherent frames between multiple users (from the servers perspective) at the expense of unconstrained exploration. This paper presents the system architecture along with an analysis and discussion of its strengths and limitations.

Web-Based Hydrodynamics Computing

Proteins are long chains of amino acids that have a definite 3-d conformation and the shape of each protein is vital to its function. Since proteins are normally in solution, hydrodynamics (describes the movement of solvent around a protein as a function of shape and size of the molecule) can be used to probe the size and shape of proteins compared to those derived from X-ray crystallography. The computation chain needed for these hydrodynamics calculations consists of several separate programs by different authors on various platforms and often requires 3D visualizations of intermediate results. Due to the complexity, tools developed by a particular research group are not readily available for use by other groups, nor even by the non-experts within the same research group. To alleviate this situation, and to foment the easy and wide distribution of computational tools worldwide, we developed a web based interactive computational environment (WICE) including interactive 3D visualization that can be used with any web browser. Java based technologies were used to provide a platform neutral, user-friendly solution. Java Server Pages (JSP), Java Servlets, Java Beans, JOGL (Java bindings for OpenGL), and Java Web Start were used to create a solution that simplifies the computing chain for the user allowing the user to focus on their scientific research. WICE hides complexity from the user and provides robust and sophisticated visualization through a web browser.