Showing papers in "IEEE Computer Graphics and Applications in 1997"

Extending distortion viewing from 2D to 3D

Abstract: Addresses the visual exploration of 3D information layouts. Several visual exploration techniques have been proposed for 2D information layouts. Many of these try to take advantage of humans' natural visual pattern-recognition abilities to understand global relationships while simultaneously integrating this knowledge with local details. This desire for detail-in-context views (also called fisheye, multiscale and distortion views) has fueled considerable research in the development of distortion viewing tools. Generally, these tools provide space for magnification of local detail by compressing the rest of the image. In considering a possible detail-in-context view for 3D layouts, we first examine 2D distortion techniques, bearing in mind the particular 3D problem of occlusion. Comparing 2D and 3D information layout adjustment tools leads directly to a 3D visual access tool that clears a line of sight to any region of interest. While our technique can extend to any type of 3D information display, we focus on graphs.

Interpolation synthesis of articulated figure motion

Abstract: Most conventional media depend on engaging and appealing characters. Empty spaces and buildings would not fare well as television or movie programming, yet virtual reality usually offers up such spaces. The problem lies in the difficulty of creating computer generated characters that display real time, engaging interaction and realistic motion. Articulated figure motion for real time computer graphics offers one solution to this problem. A common approach stores a set of motions and lets you choose one particular motion at a time. The article describes a process that greatly expands the range of possible motions. Mixing motions selected from a database lets you create a new motion to exact specifications. The synthesized motion retains the original motions' subtle qualities, such as the realism of motion capture or the expressive, exaggerated qualities of artistic animation. Our method provides a new way to achieve inverse kinematics capability-for example, placing the hands or feet of an articulated figure in specific positions. It proves useful for both real time graphics and prerendered animation production. The method, called interpolation synthesis, is based on motion capture data and it provides real time character motion for interactive entertainment or avatars in virtual worlds.

Phantom-based haptic interaction with virtual objects

Abstract: In 1993, haptic interaction with computers took a significant step forward with the development of the Phantom haptic interface. This simple device has spawned a new field analogous to computer graphics-computer haptics-defined as the discipline concerned with the techniques and processes associated with generating and displaying synthesized haptic stimuli to the human user. Inspired by the authors' previous work in interpreting robot touch sensor information and study of human touch perception, the Phantom interface permits users to feel the forces of interaction they would encounter while touching objects with the end of a stylus or the tip of their finger. The resulting sensations prove startling, and many first-time users are quite surprised at the compelling sense of physical presence they encounter when touching virtual objects. To appreciate why the Phantom system succeeded where others failed, you need to understand the nature and functioning of the human haptic system.

Comparing offset curve approximation methods

Abstract: Offset curves have diverse engineering applications, spurring extensive research on various offset techniques. In a paper on offset curve approximation (Lee et al., 1996), we suggested a new approach based on approximating the offset circle instead of the offset curve itself. To demonstrate the effectiveness of this approach, we compared it extensively with previous methods. To our surprise, Tiller and Hanson's (1984) simple method outperforms other methods for offsetting (piecewise) quadratic curves, even though its performance is not as good for high degree curves. The experimental results revealed other interesting facts, too. Had these details been reported several years ago, we believe offset approximation research might have developed somewhat differently. This article is intended to fill an important gap in the literature. We conducted qualitative as well as quantitative comparisons employing various contemporary offset approximation methods for freeform curves in the plane. We measured the efficiency of the offset approximation in terms of the number of control points generated while making the approximations within a prescribed tolerance.

Virtual human representation and communication in VLNet

Abstract: Using virtual humans to represent participants promotes realism in networked VEs. Different message types used to animate the human body and face impose varying network requirements, as analyzed here.

Analysis of cardiac function from MR images

Abstract: Recent research and development in cardiac magnetic resonance imaging (MRI) has shown that a single exam, performed entirely in an MR scanner, might well replace the current sequence of tests for coronary disease. Though an MR scanner is expensive, the ability to consolidate diagnostic tests into a single session would significantly reduce costs and increase convenience for the patient. MRI might also provide the physician with diagnostic information on myocardial function that is not available from the standard battery of tests. In this article, we concentrate on one aspect of a cardiac MRI exam that provides previously unavailable information: assessment of myocardial contraction.

3D line voxelization and connectivity control

Abstract: Voxelization algorithms that convert a 3D continuous line representation into a discrete line representation have a dual role in graphics. First, these algorithms synthesize voxel-based objects in volume graphics. The 3D line itself is a fundamental primitive, also used as a building block for voxelizing more complex objects. For example, sweeping a 3D voxelized line along a 3D voxelized circle generates a voxelized cylinder. The second application of 3D line voxelization algorithms is for ray traversal in voxel space. Rendering techniques that cast rays through a volume of voxels are based on algorithms that generate the set of voxels visited (or pierced) by the continuous ray. Discrete ray algorithms have been developed for traversing a 3D space partition or a 3D array of sampled or computed data. These algorithms produce one discrete point per step, in contrast to ray casting algorithms for volume rendering, which track a continuous ray at constant intervals, and to voxelization algorithms that generate nonbinary voxel values (for example, partial occupancies). Before considering algorithms for generating discrete lines, we introduce the topology and geometry of discrete lines.

Distributed virtual reality: supporting remote collaboration in vehicle design

Abstract: Gathering a group of remotely located engineers to design a vehicle can be difficult, especially if they live in different countries. To overcome this obstacle, we-a team at the National Center for Supercomputing Applications (NCSA) in the US in partnership with Germany's National Research Center for Information Technology (GMD) developed a collaborative virtual prototyping system for Caterpillar. The Virtual Prototyping System (VPS) will let engineers in Belgium and the US work together on vehicle designs using distributed virtual reality. The system supports collaborative design review and interactive redesign. Integrated real-time video transmissions let engineers see other participants in a shared virtual environment at each remote site's viewpoint position and orientation. Any number of remotely located sites may join in the shared VE, communicating via multicast. The system has been tested with three sites at NCSA.

Vibratory tactile display of image-based textures

Abstract: Virtual worlds must integrate tactile and force sensations to create a sense of presence. Our tactile display conveys the textural sensation of object surfaces to a user's fingertip. This vibratory tactile display contains a contact pin array that transmits vibrations to the human skin. This type of device has been investigated as a reading aid for the blind since the 1960s. A device called the Optacon, developed by J.G. Linvill and J.C. Bliss (1966) was intended for use by a visually impaired person. Therefore, methods for representing texture have not been discussed extensively for that device. We present techniques for virtually replicating surface texture sensations through a vibratory tactile display, using image data of objects. M. Minsky et al. (1990) demonstrated a method for presenting surface textures by force display, including-if needed-visual images of textures. Their system generated the images from geometrical shapes of depth maps. In contrast, we use pictures of real object surfaces to provide the distribution data for tactile stimulus.

Faster ray tracing using adaptive grids

Abstract: A new hybrid approach is presented which outperforms the regular grid technique in scenes with highly irregular object distributions by a factor of hundreds, and combined with an area interpolator, by a factor of thousands. Much has been said about scene independence of different acceleration techniques and the alleged superiority of one approach over another. Several theoretical and practical studies conducted in the past have led to the same conclusion: a space partitioning method that allows the fastest rendering of one scene often fails with another. Specialization may be the answer. This has always been pursued, consciously or not, in developing various ray-tracing systems. Despite our new algorithm's impressive efficiency, we don't interpret the new method as the fastest ray-tracing scene decomposition possible. This is because our recent groundwork experiments with a derivative method produced in some of the test scenes presented in this article produced timings that were better by approximately 50%.

Real-time fluid simulation in a dynamic virtual environment

Abstract: Simulating physically realistic complex fluid behaviors in a distributed interactive simulation (DIS) presents a challenging problem for computer graphics researchers. The authors consider how solving the 2D Navier-Stokes equations via a computational fluid dynamics method lets us map surfaces into 3D and achieves realistic real-time fluid surface behaviours.

Web-based information visualization

Abstract: Increasingly, the World Wide Web is being used to help visualize complex relational information. We have developed a number of Web-based information visualization prototypes and applications by adapting several well-known information visualization ideas and techniques for use within Web environments. Before delving into specific examples, we offer some relevant background about the Web and our use of visualization for analysis.

Multiresolution textures from image sequences

Abstract: Extracting textures from image sequences eliminates perspective distortions and removes highlights and reflections to produce high-quality multiresolution images with accurate color.

Using virtual environments to train firefighters

Abstract: Using virtual environments for training and mission rehearsal gives US Navy firefighters an edge in fighting real fires. A test run on the ex-USS Shadwell measured the improvement. The results suggest that virtual environments serve effectively for training and mission rehearsal for shipboard firefighting. VE training provides a flexible environment where a firefighter can not only learn an unfamiliar part of the ship, but also practice tactics and procedures for fighting a fire by interacting with simulated smoke and fire without risking lives or property. These tests proved a successful first step in developing a new training technology for shipboard firefighting based on immersive virtual environments. The tests also indicated potential areas for improvement, requiring additional research. User interaction techniques for manipulating objects in VEs need further study, along with usability studies to determine their effectiveness or utility. Other areas that could enhance VE training systems include more natural and intuitive I/O devices such as 3D sound, speech and natural language input, integrated multimedia and hypermedia instruction, and multi user interaction.

Faking dynamics of ropes and springs

Abstract: This article presents a method to model flexible linear bodies: ropes, cords, springs, and the like, for animation production. The resulting models can easily be animated in a manner that convincingly fakes dynamic behavior. The models were animated using the keyframe animation system, which provides traditional spline-based control of the models' animatable parameters.

Collaborative 3D visualization with CSpray

Abstract: 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.

mWorld: A multiuser 3D virtual environment

Abstract: mWorld integrates 3D virtual-scene generation tools and synchronous, asynchronous, and time-dependent data communication techniques to enable cooperative 3D design and visualization across networks.

Interactive space deformation with hardware-assisted rendering

Abstract: The authors introduce a new approach for the deformation of surface and raster models in two and three dimensions. Rather than deforming the model, they deform the agents employed to render it. The method uses one deformation tool (the deflector) to deform any object that is ray traceable. Based on deforming the rendering primitives rather than objects, the approach invests computation effort only in those regions of the model that contribute to the final image.

TennisViewer: a browser for competition trees

Abstract: A tennis novice watching a match for the first time might be surprised that the crowd erupts with cheers when a player wins one point, then barely applauds when he wins the next. The crowd is not necessarily fickle; some points are genuinely more important than others because a tennis match is hierarchically structured. One match consists of several sets. One set consists of several games. One game consists of several points. The match-winning point is the most important one. How can we make that importance visible? Our goal is to let a fan, a player, or a coach examine tennis data visually, extract the interesting parts, and jump from one item to another quickly and easily. The visualization tool should help parse the elements of a match. We developed an interactive system called TennisViewer to visualize the dynamic, tree-structured data representing a tennis match. It provides an interface for users to quickly explore tennis match information. The visualization tool reveals the overall structure of the match as well as the fine details in a single screen. It uses a 2D display of translucent layers, a design that contains elements of Tree-Maps and of the Visual Scheduler system, which was designed to help faculty and students identify mutually available (transparent) time slots when arranging group meetings. TennisViewer provides MagicLens filters to explore specialized views of the information and a time-varying display to animate all or part of a match.

The FoxTrax hockey puck tracking system

Abstract: Though we had our share of problems developing and deploying this puck-tracking system, it proved to be an overall success. It resulted in one patent (for the puck) and five patents pending for the system as a whole. Also, Fox Sports' NHL coverage enjoys significantly higher ratings-in large part, we think, because of the tracking system. While we certainly had moments of doubt, the Puck Truck proved successful at every event it attended. It's true that some fans don't care for the effect, but many think it's an improvement. Over the last year we've been working to improve the system so that it will track the puck more accurately. Additional improvements that may show up this season should make the system more palatable to all fans.

The Virtual Reality Gorilla Exhibit

Abstract: The Virtual Reality Gorilla Exhibit is an immersive virtual environment which lets students assume the persona of an adolescent gorilla, enter into one of the gorilla habitats at Zoo Atlanta in Atlanta, Georgia, and interact as part of a gorilla family unit. The exhibit combines a model of Zoo Atlanta's Gorilla Habitat 3-home of Willie B, a 439 pound male silverback gorilla and his family group-with computer generated gorillas whose movements and interactions are modeled as accurate representations of gorilla behaviors. The VR Gorilla Exhibit's goal is to create an experiential educational tool for middle school students to learn about gorillas' interactions, vocalizations, social structures, and habitat.

Animals with anatomy

Abstract: In general, computer graphics achieves greater realism using methods that simulate the real world rather than ad hoc methods that just appear somewhat realistic. To this end, we need to develop modeling and animation approaches based on anatomical and physiological principles. The method presented in this article models any animal that has a jointed endoskeleton moved by muscles and covered by a flexible skin. This semi-automated method permits user-defined parameters and achieves comfortable interactive speeds on graphics workstations.

Floating-point tricks

Abstract: The author discusses IEEE floating point representation that stores numbers in what amounts to scientific notation. He considers the sign bit, the logarithm function, function approximations, errors and refinements.

A simple technique for NURBS shape modification

Abstract: Non-uniform rational B-splines (NURBS) have become a de-facto industry standard primarily because they offer a unified mathematical form for representing both freeform shapes and analytical curves or surfaces. Despite these advantages, designers need software that lets them work with NURBS in a natural way. The paper presents a unified approach to NURBS shape modification that builds on a perspective functional transformation of arbitrary origin and provides a homogeneous interface based on simple, easily understood geometric concepts.

Virtual hell: a trip through the flames

Abstract: In immersive virtual environments, our eyes and ears are usually the most important channels of perception. However, you might expect that their creators would include other senses in VEs so as to represent the largest range of stimuli. After all, humans are creatures of many senses and rely upon all of them in day-to-day living. In crafting virtual worlds for exploration, VE developers usually aim for as much realism as possible given the constraints of equipment and cost. Unfortunately, force and tactile feedback still have a long way to go, although tactile feedback models can simulate local geometry, texture reproduction, and heat flux and temperature for replicating collision detection. To investigate the latter options, I developed a complete thermal feedback system, the VR Thermal Kit, which includes different components to model, control, and physically generate stimuli on the operator's skin (usually the hand and exposed parts of the body). The results of my study concentrate on interaction paradigms and haptic rendering. They also enhance the level of immersion.

Information appliances and tools in Visage

Abstract: A workspace for information analysis must support two types of analysis: routine information reporting and exploratory analysis. We have been developing a workspace called Visage to address both types of analysis tasks. Our goal is for expert users to move easily between routine tasks and exploratory data analysis as situations demand. Furthermore, recognizing the inherent complexity of data analysis, we want a system that is accessible to occasional users yet simultaneously provides power and flexibility for expert users. Ideally, such a system should support a gradual shift to increasing expertise so that occasional users of routine interfaces can perform more detailed analyses if needed. Visage addresses these needs by providing a consistent interface to a wide variety of data manipulation and visualization primitives. Plus, it lets users combine these operations to create appliances-special-purpose applications capturing multiple steps of a routine data analysis process-in a single, simple interface. Analysts thus benefit from a common set of operations and ways to integrate information across applications. Visage provides both basic tools and specialized information appliances to help them.

Business visualization applications

Abstract: Three-dimensional computer graphics can be extremely expressive. With the correct approach to a layout's visual design, people can quickly and easily comprehend large amounts of information. You can convey far more information in 3D than with 2D bar charts, or rows and columns of numbers. This article provides examples of information visualization applications in several industries, including the capital markets, retail banking, manufacturing, and consumer product goods. These examples help show what it means to put abstract information in 3D and what benefits result.

Enhanced illustration using Magic Lens filters

Abstract: In computerized 2.5D illustration systems such as Adobe Illustrator or CorelDraw, users construct pictures by layering geometrical shapes and specifying graphical properties such as line width, fill color, and transparency. In these systems, the act of applying a graphical property is closely tied to the way the individual objects in the design are constructed. For example, filled regions must be explicitly constructed and closed. Line and fill properties must be applied to complete outlines or line segments. Transformations can only be applied to complete objects or groups of objects. The designer must always plan to create object boundaries to define the extent of any visual effect. Effects that appear to cross object boundaries require the introduction of extra shapes and boundaries into the picture. We describe the value of including spatially bounded visual filters, called Magic Lens filters, as integrated elements in graphical illustrations. Because the effect of a Magic Lens filter is visible only within the lens' boundary, the extent of this effect can be manipulated independently of the boundaries of the objects seen through it. This adds a new design element to the standard illustration system paradigm, making many forms of illustration easier to create. Magic Lens filters were introduced in 1993 as components of see-through user interfaces (E.A. Bier et al., 1993).

Seamless interaction in virtual reality

Abstract: Jot is a novel research interface for virtual reality modeling. This system seamlessly integrates and applies a variety of virtual and physical tools, each customized for specific tasks. The Jot interface not only moves smoothly from one tool to another but also physically and cognitively matches individual tools to the tasks they perform. In particular, we exploit the notion that gestural interaction is more direct, in many cases, than traditional widget based interaction. We also respect the time tested observation that some operations-even conceptually three dimensional ones-are better performed with 1D or 2D input devices, whereas other operations are more naturally performed using stereoscopic views, higher DOF input devices, or both. Ultimately we strive for a 3D modeling system with an interface as transparent as the interaction afforded by a pencil and a sheet of paper. For example, the system should facilitate the tasks of drawing and erasing and provide an easy transition between the two. Jot emerged from our previous work on a mouse based system, called Sketch, for gesturally creating imprecise 3D models. Jot extends Sketch's functionality to a wider spectrum of modeling, from concept design to detailed feature based parametric parts. Jot also extends the interaction in Sketch to better support individual modeling tasks. We extended Sketch's gestural framework to integrate interface components ranging from traditional desktop interface widgets to context sensitive gestures to direct manipulation techniques originally designed for immersive VR.

Using MineSet for knowledge discovery

Abstract: MineSet aids knowledge discovery and supports decision making based on relational data. It uses visualization and data mining to arrive at interesting results. Providing diverse visualization tools lets users choose the most appropriate method for a given problem. The client-server architecture performs most of the computationally intensive tasks on a server, while the processed results return to the client for visualization. The paper discusses MineSet database visualization and data mining visualization.