Showing papers by "Jim X. Chen published in 1999"

A Model for Understanding How Virtual Reality Aids Complex Conceptual Learning

Abstract: Designers and evaluators of immersive virtual reality systems have many ideas concerning how virtual reality can facilitate learning. However, we have little information concerning which of virtual reality's features provide the most leverage for enhancing understanding or how to customize those affordances for different learning environments. In part, this reflects the truly complex nature of learning. Features of a learning environment do not act in isolation; other factors such as the concepts or skills to be learned, individual characteristics, the learning experience, and the interaction experience all play a role in shaping the learning process and its outcomes. Through Project Science Space, we have been trying to identify, use, and evaluate immersive virtual reality's affordances as a means to facilitate the mastery of complex, abstract concepts. In doing so, we are beginning to understand the interplay between virtual reality's features and other important factors in shaping the learning process and learning outcomes for this type of material. In this paper, we present a general model that describes how we think these factors work together and discuss some of the lessons we are learning about virtual reality's affordances in the context of this model for complex conceptual learning.

Real-time simulation of dust behavior generated by a fast traveling vehicle

Abstract: Simulation of physically realistic complex dust behavior is very useful in training, education, art, advertising, and entertainment. There are no published models for real-time simulation of dust behavior generated by a traveling vehicle. In this paper, we use particle systems, computational fluid dynamics, and behavioral simulation techniques to simulate dust behavior in real time. First, we analyze the forces and factors that affect dust generation and the behavior after dust particles are generated. Then, we construct physically-based empirical models to generate dust particles and control the behavior accordingly. We further simplify the numerical calculations by dividing dust behavior into three stages, and establishing simplified particle system models for each stage. We employ motion blur, particle blending texture mapping, and other computer graphics techniques to achieve the final results. Our contributions include constructing physically-based empirical models to generate dust behavior and achieving simulation of the behavior in real time.

3D knee modeling and biomechanical simulation

Abstract: Knee osteotomy is a kind of orthopedic surgery to realign the lower limb by opening or cutting a bone wedge from the leg. It is a better alternative than other types of knee-replacement surgeries, especially for young people. However, knee osteotomy requires understanding the imbalance of stresses at the knee joint, analyzing an abnormal gait cycle, and cutting the bone wedge precisely. Therefore, it is difficult and can cause further damage even though it is simply a bone cut. While some computer based surgical simulation systems have been developed to help surgeons perform knee surgeries, the knee models used either are not patient-specific or lack kinematic and kinetic information. We discuss how we use computer graphics, physics based modeling, and interactive visualization to assist knee-surgery study and osteotomies. Our patient-specific 3D knee surface model helps us calculate the contact stresses at the knee joint, perform virtual surgery, and record data from surgery simulation.

Integrating physics-based computing and visualization: modeling dust behavior

Abstract: Simulating physically realistic, complex dust behaviors is useful in interactive graphics applications, such as those used for education, entertainment, or training. Training in virtual environments is a major topic for research and applications, and generating dust behaviors in real time significantly increases the realism of the simulated training environment. We introduce a method for simulating the dust behaviors that a fast-traveling vehicle causes. Our method combines particle systems, rigid-body particle dynamics, computational fluid dynamics (CFD), rendering, and visualization techniques. Our work integrates physics-based computing and graphical visualization for applications in simulated virtual environments.

Approximate Line Scan‐Conversion and Antialiasing

Abstract: This paper presents an approximate multiple segment line scan-conversion method — the Slope Table Method. The statistics show that the new method can increase the percentage of multiple segment lines (i.e., lines with more than one segment) in an N×N raster area from about 39% to more than 99%. In software implementation for scan-conversion and antialiasing of randomly generated lines, this method is on average more than 6 times faster than Gupta's antialiasing line algorithm. Compared with other line scan-conversion methods, the method may choose pixels which are not the closest to the line (i.e., error pixels). Here the paper demonstrates that the visual effect is acceptable in most applications with the error pixels.

A virtual reality system for knee diagnosis and surgery simulation

Abstract: This paper describes the design and development of a VR system that can assist orthopedic diagnosis and surgery. A realistic 3D knee surface model, integrated with motion analysis, is used to visualize the geometrical and biomechanical characteristics of human knee joint. The system can be used to perform pre-operative surgery simulation and evaluation in a VR environment.

Near real-time simulation of particle systems

Abstract: Simulation of particle systems is time consuming. However, many particle system applications require fast interactive animations. For example, simulation of physically realistic complex dust behaviors is very useful in training, education, art, advertising, and entertainment. There are no published models for real-time simulation of dust behavior generated by a traveling vehicle. In this paper we use particle systems, computational fluid dynamics, and behavioral simulation techniques to simulate dust behavior in real time. First, we analyze the forces and factors that affect dust generation and the behavior after dust particles are generated. Then, we construct physically-based empirical models to generate dust particles and control the behavior accordingly. We further simplify the numerical calculations by dividing dust behavior into three stages, and establishing simplified particle system models for each stage. We employ motion blur, particle blending, texture mapping, and other computer graphics techniques to achieve the final results. Our contributions include constructing physically-based empirical models to generate dust behavior and achieving simulation of the behavior in real time.

Distributed interactive learning environment

Abstract: We present strategies and approaches used to implement a synthetic learning environment which includes networking, distributed interactive simulation, physically-based modeling, computational steering, and virtual reality for learning abstract scientific concepts. The resulting technology is a testbed that reflects the benefits of a schoolhouse for training and education, especially for learning scientific abstract concepts. Students are allowed to interact with one another and engage in realistic collaborative exercises. Our network architecture and protocol allow the interactive networked environment to be much more scalable. Our innovative use of computational steering and interactive visualization allows students to visualize and manipulate the physical process, and understand the abstract concept much easier. We use fluid dynamics as a case study to demonstrate this learning environment.

Method and apparatus for generating a straight line

Abstract: An apparatus, method and computer readable medium containing a program are described for generating a line corresponding to a desired straight line, including identifying a plurality of segments between two endpoints of the desired straight line to be generated, and generating the line corresponding to the desired straight line comprising identifying, in parallel, pixels in each of more than one of the segments. By processing in parallel, processor time is reduced. Also, anti-aliasing techniques can be similarly performed in parallel to reduce processor time.

Applications of Computer Graphics Software Tools

Abstract: Graphics software tools open up new possibilities for researchers and scientists, but learning graphics programming might seem time-consuming or difficult, and the many new graphics tools might seem overwhelming. Fortunately, if you know how graphics work and the functions of basic graphics tools, you can understand and employ some of the tools without becoming a graphics expert. Our purpose is to introduce and categorize some graphics tools and their applications, though not to provide an exhaustive list of tools and their explicit functions, because new graphics tools with various combinations of functions emerge every day. Through explaining and categorizing a few graphics tools and their primary applications, we hope to show you the different functions and applications of computer graphics so visualization, modeling, simulation, and virtual reality can complement your work.

A jump on visualization: the bottom-up approach

Abstract: Visualization-using computer graphics to gain insight into complex phenomena-is a powerful tool for scientific computing, but visualization experts and computational scientists seem to live in separate worlds. Recently, however, the gap between these two worlds has narrowed, and scientific visualization has come to represent the marriage of supercomputing and graphics. Computer graphics provides the basic functions for generating complex images from abstract data; visualization employs graphics to make pictures that provide insight into abstract data and symbols. The pictures can directly portray data or present it in an innovative form. Learning programming in graphics and visualization might seem time-consuming or difficult, and the many tools and programs might seem overwhelming. Fortunately, if you know what graphics provide and how they work, you can start using and researching visualization without becoming a graphics expert. In this article, I explain how to work with graphics and I discuss various visualization techniques, tools and areas of research