bluuebunny/crossref_metadata_2025 huggingface dataset:
ConMan
Authors: Haeberli Paul E.
Published: November 2005

Traditionally, interactive applications have been difficult to build, modify and extend. These integrated applications provide bounded bounded functionality, have a single thread of control and a fixed user interface that must anticipate everything the user will need.Current workstations allow several processes to share the screen. With proper communication between processes, it is possible to escape previous models for application development and evolution.
ConMan
is a high-level visual language we use on an IRIS workstation that lets users dynamically build and modify graphics applications. To do this, a system designer disintegrates complex applications into modular components. By interactively connecting simple components, the user constructs a complete graphics application that matches the needs of a task. A connection manager controls the flow of data between individual components. As a result, we replace the usual user-machine dialog with a dynamic live performance that is orchestrated by the user.
Development models of herbaceous plants for computer imagery purposes
Authors: Prusinkiewicz Przemyslaw , Lindenmayer Aristid , Hanan James
Published: November 2005

In this paper we present a method for modeling herbaceous plants, suitable for generating realistic plant images and animating developmental processes. The idea is to achieve realism by simulating mechanisms which control plant growth in nature. The developmental approach to the modeling of plant architecture is extended to the modeling of leaves and flowers. The method is expressed using the formalism of L-systems.
The motion dynamics of snakes and worms
Authors: Miller Gavin S. P.
Published: November 2005

Legless figures such as snakes and worms are modelled as mass-spring systems. Muscle contractions are simulated by animating the spring tensions. Directional friction due to the surface structure is included in the dynamic model and legless figure locomotion results. Various modes of locomotion are described.
A modeling system based on dynamic constraints
Authors: Barzel Ronen , Barr Alan H.
Published: November 2005

We present "dynamic constraints," a physically-based technique for constraint-based control of computer graphics models. Using dynamic constraints, we build objects by specifying geometric constraints; the models assemble themselves as the elements move to satisfy the constraints. The individual elements are rigid bodies which act in accordance with the rules of physics, and can thus exhibit physically realistic behavior. To implement the constraints, a set of "constraint forces" is found, which causes the bodies to act in accordance with the constraints; finding these "constraint forces" is an
inverse dynamics
problem.
A recursive evaluation algorithm for a class of Catmull-Rom splines
Authors: Barry Phillip J. , Goldman Ronald N.
Published: November 2005

It is known that certain Catmull-Rom splines [7] interpolate their control vertices and share many properties such as affine invariance, global smoothness, and local control with B-spline curves; they are therefore of possible interest to computer aided design. It is shown here that another property a class of Catmull-Rom splines shares with B-spline curves is that both schemes possess a simple recursive evaluation algorithm. The Catmull-Rom evaluation algorithm is constructed by combining the de Boor algorithm for evaluating B-spline curves with Neville's algorithm for evaluating Lagrange polynomials. The recursive evaluation algorithm for Catmull-Rom curves allows rapid evaluation of these curves by pipelining with specially designed hardware. Furthermore it facilitates the development of new, related curve schemes which may have useful shape parameters for altering the shape of the curve without moving the control vertices. It may also be used for constructing transformations to Bézier and B-spline form.
Hierarchical B-spline refinement
Authors: Forsey David R. , Bartels Richard H.
Published: November 2005

Refinement
is usually advocated as a means of gaining finer control over a spline curve or surface during editing. For curves, refinement is a local process. It permits the change of control vertices and subsequent editing of the detail in one region of the curve while leaving control vertices in other regions unaffected. For tensor-product surfaces, however, refinement is not local in the sense that it causes control vertices far from a region of interest to change as well as changing the control vertices that influence the region. However, with some care and understanding it is possible to restrict the influence of refinement to the locality at which an editing effect is desired. We present a method of localizing the effect of refinement through the use of
overlays
, which are hierarchically controlled subdivisions. We also introduce two editing techniques that are effective when using overlays: one is direct surface manipulation through the use of
edit points
and the other is
offset referencing
of control vertices.
Intensity fluctuations and natural texturing
Authors: Krueger Wolfgang
Published: November 2005

A model for texturing of surfaces is introduced based on the concept of light intensity fluctuations. During the evaluation of the reflected intensity in the rendering process a non-Gaussian stochastic component is added which is governed by electromagnetic scattering theory. This component simulates the appearence of macroscopic surface irregularities in the image plane by considering not only the mean value of the intensity, given by the usual specular contribution, but also its variance and autocorrelation function. The variance generates the strength and distribution of the intensity fluctuations and the spatiotemporal auto-correlation function can be used to model the form and temporal development of the texture patterns. With an appropriate choice of a few parameters, soft intensity perturbations and bumpy speckle patterns as well as glint effects can be created.
Constant-time filtering with space-variant kernels
Authors: Fournier Alain , Fiume Eugene
Published: November 2005

Filtering is an essential but costly step in many computer graphics applications, most notably in texture mapping. Several techniques have been previously developed which allow prefiltering of a texture (or in general an image) in time that is independent of the number of texture elements under the filter kernel. These are limited, however, to space-invariant kernels whose shape in texture space is the same independently of their positions, and usually are also limited to a small range of filters.We present here a technique that permits constant-time filtering for space-variant kernels. The essential step is to approximate a filter surface in texture space by a sum of suitably-chosen basis functions. The convolution of a filter with a texture is replaced by the weighted sum of the convolution of the basis functions with the texture, which can be precomputed. To achieve constant time, convolutions with the basis functions are computed and stored in a pyramidal fashion, and the right level of the pyramid is selected so that only a constant number of points on the filter kernel need be evaluated.The technique allows the use of arbitrary filters, and as such is useful to explore interesting mappings and special filtering techniques. We give examples of applications to perspective and conformal mappings, and to the use of filters such as gaussians and sinc functions.
Virtual graphics
Authors: Voorhies Douglas , Kirk David , Lathrop Olin
Published: November 2005

Graphics can be implemented as a virtual system resource. This abstraction appears to each application on a multiprocessing workstation as a dedicated rendering and display pipeline. A variety of simple mechanisms support the simultaneous display of different types of images and eliminate the need for low-level device driver software. They permit applications to embed graphics instructions directly in their code. The abstraction allows for cleaner software design, higher performance, and effective concurrent use of the display by several applications.
A display system for the Stellar graphics supercomputer model GS1000
Authors: Apgar Brian , Bersack Bret , Mammen Abraham
Published: November 2005

This paper describes a high performance display system that has been incorporated into the overall architecture of the Stellar Graphics Supercomputer Model GS1000. The display system is tightly coupled to the CPU, memory system and vector processing unit of this supercomputer, and is capable of rendering 150,000 shaded triangles/sec, and 600,000 short vectors/sec. The goal of the architecture is to share hardware resources between the CPU and display system and achieve a high bandwidth connection between them. This coupling of the display system and the processor, the architecture of the rendering processor, and the two ASICs that are used to implement the rendering processor are described.In addition, the display system architecture is contrasted to other approaches to high performance graphics, and design trade-offs and possible extensions are described. The implementation of popular display algorithms on the architecture is discussed, and their performance specified. The reader is advised that Stellar Computer Inc. is seeking patent protection for work described in this paper.
Terrain simulation using a model of stream erosion
Authors: Kelley Alex D. , Malin Michael C. , Nielson Gregory M.
Published: November 2005

The major process affecting the configuration and evolution of terrain is erosion by flowing water. Landscapes thus reflect the branching patterns of river and stream networks. The network patterns contain information that is characteristic of the landscape's topographic features. It is therefore possible to create an approximation to natural terrain by simulating the erosion of stream networks on an initially uneroded surface. Empirical models of stream erosion were used as a basis for the model presented here. Stream networks of various sizes and shapes are created by the model from a small number of initial parameters. The eroded surface is represented as a surface under tension, using the tension parameter to shape the profiles of valleys created by the stream networks. The model can be used to generate terrain databases for flight simulation and computer animation applications.
Motion interpolation by optimal control
Authors: Brotman Lynne Shapiro , Netravali Arun N.
Published: November 2005

Motion Interpolation, which arises in many situations such as
Keyframe Animation
, is the synthesis of a sequence of images portraying continuous motion by interpolating between a set of
keyframes
. If the keyframes are specified by parameters of moving objects at several instants of time, (e.g., position, orientation, velocity) then the goal is to find their values at the intermediate instants of time. Previous approaches to this problem have been to construct these intermediate, or
in-between
, frames by interpolating each of the motion parameters independently. This often produces unnatural motion since the physics of the problem is not considered and each parameter is obtained independently. Our approach models the motion of objects and their environment by differential equations obtained from classical mechanics. In order to satisfy the constraints imposed by the keyframes we apply external control. We show how smooth and natural looking interpolations can be obtained by minimizing a combination of the control energy and the roughness of the trajectory of the objects in 3D-space. A general formulation is presented which allows several trade-offs between various parameters that control motion. Although optimal parameter values resulting in the best subjectively looking motion are not yet known, our simulations have produced smooth and natural motion that is subjectively better than that produced by other interpolation methods, such as the cubic splines.
Getting graphics in gear
Authors: Deyo Rod , Briggs John A. , Doenges Pete
Published: November 2005

Man-in-the-loop simulation uses a person in the control loop to provide feedback to the system operations. Proper operator cueing must be provided to ensure a realistic response. Real-time computer graphics and dynamics both play dominant roles in providing these necessary cues. Dynamics simulation of modern vehicles requires a multi-body non-linear approach for acceptable fidelity of motion. A vehicle can be modeled as a set of linked rigid bodies, whose connections are described by a graph. Real-time constraints on the computation of non-linear dynamics equations require the development of naturally parallel recursive algorithms, whose organization closely follows the system graph. Significant speed-up can be accomplished using these parallel algorithms.
Federal funding in computer science: a preliminary report
Authors: Yudken Joel S. , Simons Barbara
Published: November 2005

Dr. Joel S. Yudken is Director of the Project on Funding Policy in Computer Science. Dr. Barbara Simons, is vice-chair of the Special Interest Group on Automata and Computability Theory (SIGACT) of the Association for Computing Machinery (ACM). Dr. Simons is also chair of the Committee on Scientific Freedom and Human Rights of the ACM. This article is adapted from a paper presented at the Conference on Directions and Implications of Advanced Computing, sponsored by CPSR/Seattle in July.This study is sponsored by the Science Policy Committee of SIGACT. It has been partially funded by SIGACT, the MIT Lab for Computer Science, the Rockefeller Family Associates and the SIG chairs and SIGBOARD. It has also been endorsed by the executive committees of SIGGRAPH, the Association for Women in Mathematics, the IEEE Society on Social Implications of Technology and Computer Professional for Social Responsibility. The authors of this report assume full responsibility for its content. It does not necessarily represent the views of the sponsoring, contributing or endorsing organizations.
Dissertation Abstracts in Computer Graphics
Authors: McConnell Jeffrey J.
Published: November 2005

This paper is the first of a yearly compendium of abstracts from masters and doctoral theses in computer graphics. The compendium is being provided as a guide to the work being done in computer graphics by graduate students. Any requests for further information about a thesis or graduate student should be directed to the institution involved.This year's compendium has 54 entries from 23 institutions. The list is by no means complete as there are several prominent graduate schools missing. It is hoped that future participation will be more widespread.The deadline for the 1989 compendium is
September 1, 1988
. Submissions should follow the format below and can be sent (by electronic mail preferably) to either of the addresses above.I would like to thank Canisius College and WPI for their support of this project. Specifically. I would like to thank Veronica Serwacki, Kim Smith and Ken Downey, all of Canisius College for entering those abstracts arriving in paper form. I, however, take full responsibility and apologize for all errors.
Tricks to animating characters with a computer
Authors: Lasseter John
Published: November 2005

When I presented the first animation I had created with a computer,
The Adventures of André and Wally B.,
at SIGGRAPH 84, a number of people asked me what cool new software I had used to achieve such believable characters. I explained to them that the software was a keyframe animation system, not much different in theory than other systems that were around then. What was different was that I was using basic animation principles that I had learned as a traditional animator. It was not the software that gave life to the characters, it was these principles of animation, these tricks of the trade that animators had developed over 50 years ago. I was surprised at how few people in the computer animation community were aware of these principles.Traditional animation is basically one trick after another. Whatever it takes to get it working right on the screen is fair game. It should be the same in computer animation. At Pixar, we constantly use tricks, old and new, to get what we need on the screen. In this talk, I will give away a few trade secrets that will be useful to anyone attempting to animate characters with computers, regardless of the software they are using.
Threading a sophomore computer animation curriculum
Authors: Cumbie-Jones Claudia
Published: November 2005

One of the major problems facing educators who teach computer animation is how to balance the technical and conceptual skills required to produce effective computer animation in a manner that is holistic. Often a single class cannot deal with both the conceptual and technical issues involved. When courses are offered separately, often students don't make the connections between them. By threading the course objectives across multiple classes, students are exposed to the
connections
between concepts and technology, and are challenged to build their own "conceptual bridges" to integrate ideas and techniques. This article addresses issues specific to teaching computer animation: how do you introduce students to all of the technical and conceptual aspects of animation in a way that will empower them to produce meaningful work?The Computer Animation Department at Ringling School of Art and Design has three required courses for the major in the fall semester of the sophomore year. These courses serve as an introduction to animation techniques and processes which students use throughout the curriculum. The courses are Computer Animation I, Concept Development I and Traditional Animation I. For the past two years, the faculty has been working on threading the course objectives in order to make students aware of the concepts and principles that are interwoven throughout the computer animation curriculum.This "threaded curriculum" is a work in progress. Our initial goals are to define the groupings of course objectives that the classes have in common, and to begin to track the connections. As we continue to refine the process, we are seeing more ways in which the connections can be made deeper, and we have also identified problem areas where the threading does not seem to be as complete.
Visfiles
Authors: Hibbard Bill
Published: November 2005

Arguably the trigger for the success of the World Wide Web in the early 1990s was its ability to convey images as well as text. Documents could include colour pictures at no extra cost. In those days, however, scientific visualization in a Web context was a passive activity. A scientist would create a visualization using a conventional system, and publish it on a website - for a reader to later observe. The Web was simply a publication medium. Today of course the Web represents a rich distributed computing environment: visualization can now be executed as a live process with active engagement from the audience.A new field of Web-based visualization has emerged.
Education
Authors: Eber Dena , Wolfe Rosalee
Published: November 2005

Instructors in both art and computer science departments experience difficulties in motivating students to develop a visual literacy in computer graphics. Although a highly prized skill in industry, visual literacy is intimidating to computer science students because they are uneasy about using their eyes to examine computer-synthesized images. Even though they are used to using their eyes for acquiring information, the topics of analysis and interpretation intimidate art students. Further, art students may not have as much background to understand the technical terminology. This first column in a two-part series discusses an interdisciplinary approach for teaching visual literacy that overcomes these obstacles. With this approach students become more familiar with the limits and possibilities of the medium of computer graphics, learn how to analyze and talk about what visual images might mean and develop a deeper understanding of time constraints. In addition, they gain confidence with technological terminology and the idea of suggesting alternative algorithms to create a desired visual "look." As a result, both computer science and art students become more able to communicate effectively about and with visual imagery.
Application of VisAD in hydrological modeling and simulation
Authors: Taddei Ugo , David Olaf , Michl Christian
Published: November 2005

For visualization of distributed hydrological phenomena, a multidimensional visualization tool such as VisAD embeds sophisticated visualization techniques in hydrological models. Heterogeneous hydrological properties can be visualized draped on top of a digital elevation model (DEM), in order to model parametrization or results. This article discusses how the VisAD library was applied to hydrology related information in the headwater catchments of the Schmücker Graben and the Steinbach utilizing DEMViewer.
Rivet
Authors: Bosch Robert , Stolte Chris , Tang Diane , Gerth John , Rosenblum Mendel , Hanrahan Pat
Published: November 2005

Rivet is a visualization system for the study of complex computer systems. Since computer systems analysis and visualization is an unpredictable and iterative process, a key design goal of Rivet is to support the rapid development of interactive visualizations capable of visualizing large data sets. In this paper, we present Rivet's architecture, focusing on its support for varied data sources, interactivity, composition and user-defined data transformations. We also describe the challenges of implementing this architecture efficiently and flexibly. We conclude with several examples of computer systems visualizations generated within Rivet, including studies of parallel systems, superscalar processors and mobile network usage.
Practical scientific visualization examples
Authors: Taylor Russell M.
Published: November 2005

Scientific visualization has yet to become a discipline founded on well-understood principles. In some cases we have rules of thumb, and there are studies that probe the capabilities and limitations of specific techniques. For the most part, however, visualization consists of a collection ofad hoctechniques and lovely examples. This article collects examples where visualization was found to be useful for particular insights or where it enabled new and fruitful types of experiment.
Are you getting all that you can out of ACM SIGGRAPH?
Authors: Di Leo Etta
Published: November 2005

Whether you are fortunate enough to work in an industry you love, or you have aspirations to do so one day, don't overlook the benefits that come with being a member of your local ACM SIGGRAPH.With a membership made up of professionals from all aspects of computing from academia to research to business - you'll discover a level of information and insight that cannot easily be found in any other way. Chapter membership provides a unique combination of social interaction and professional dialogue among peers. Workshops, tutorials, seminars and speakers provide both educational opportunities and the chance to meet experts in your field.
The synthesis and rendering of eroded fractal terrains
Authors: Musgrave F. K. , Kolb C. E. , Mace R. S.
Published: November 2005

In standard fractal terrain models based on fractional Brownian motion the statistical character of the surface is, by design, the same everywhere. A new approach to the synthesis of fractal terrain height fields is presented which, in contrast to previous techniques, features locally independent control of the frequencies composing the surface, and thus local control of fractal dimension and other statistical characteristics. The new technique, termed
noise synthesis
, is intermediate in difficulty of implementation, between simple stochastic subdivision and Fourier filtering or generalized stochastic subdivision, and does not suffer the drawbacks of creases or periodicity. Varying the local crossover scale of fractal character or the fractal dimension with altitude or other functions yields more realistic first approximations to eroded landscapes. A simple physical erosion model is then suggested which simulates hydraulic and thermal erosion processes to create gloabl stream/valley networks and talus slopes. Finally, an efficient ray tracing algorithm for general height fields, of which most fractal terrains are a subset, is presented.
From splines to fractals
Authors: Szeliski R. , Terzopoulos D.
Published: November 2005

Deterministic splines and stochastic fractals are complementary techniques for generating free-form shapes. Splines are easily constrained and well suited to modeling smooth, man-made objects. Fractals, while difficult to constrain, are suitable for generating various irregular shapes found in nature. This paper develops
constrained fractals
, a hybrid of splines and fractals which intimately combines their complementary features. This novel shape synthesis technique stems from a formal connection between fractals and generalized energy-minimizing splines which may be derived through Fourier analysis. A physical interpretation of constrained fractal generation is to drive a spline subject to constraints with modulated white noise, letting the spline diffuse the noise into the desired fractal spectrum as it settles into equilibrium. We use constrained fractals to synthesize realistic terrain models from sparse elevation data.
Hardware acceleration for Window systems
Authors: Rhoden D. , Wilcox C.
Published: November 2005

Graphics pipelines are quickly evolving to support multitasking workstations. The driving force behind this evolution is the window system, which must provide high performance graphics within multiple windows, while maintaining interactivity. The virtual graphics system presented by [7] provides a clean solution to the problem of context switching graphics hardware between processes, but does not solve all the problems associated with sharing graphics pipelines.The primary difficulty in context switching a graphics accelerator is the pipeline latency encountered during a pipeline flush. This latency removes the responsiveness and interactivity of the graphics system. As primitives become more complex and pipelines become longer, pipeline latency grows. Hardware solutions are described which further accelerate the window system by eliminating the need for pipeline flushing and resynchronization. An overview of the entire system is presented, highlighting the hardware mechanisms which contribute to window acceleration.
The pixel machine: a parallel image computer
Authors: Potmesil Michael , Hoffert Eric M.
Published: November 2005

We describe the system architecture and the programming environment of the Pixel Machine - a parallel image computer with a distributed frame buffer.The architecture of the computer is based on an array of asynchronous MIMD nodes with parallel access to a large frame buffer. The machine consists of a pipeline of
pipe nodes
which execute sequential algorithms and an array of
m
×
n
pixel nodes which execute parallel algorithms. A
pixel node
directly accesses every
m
-th pixel on every
n
-th scan line of an interleaved frame buffer. Each processing node is based on a high-speed, floating-point programmable processor.The programmability of the computer allows all algorithms to be implemented in software. We present the mappings of a number of geometry and image-computing algorithms onto the machine and analyze their performance.
Illumination networks: fast realistic rendering with general reflectance functions
Authors: Buchalew Chris , Fussell Donald
Published: November 2005

We present a technique for modeling global illumination which allows a wide variety of reflectance functions. Scene coherence is exploited in a preprocessing step in which the geometry is analyzed using iterative techniques. Memory is traded for speed, in anticipation of the high memory capacities of workstations of the future. The algorithm operates well over a wide range of time and image quality constraints: realistic results may be produced very quickly while very accurate results require more time and space. The method can be extended for animation and parallelization.
Near real-time shadow generation using BSP trees
Authors: Chin Norman , Feiner Steven
Published: November 2005

This paper describes an object-space shadow generation algorithm for static polygonal environments illuminated by movable point light sources. The algorithm can be easily implemented on any graphics system that provides fast polygon scan-conversion and achieves near real-time performance for environments of modest size. It combines elements of two kinds of current shadow generation algorithms: two-pass object-space approaches and shadow volume approaches. For each light source a Binary Space Partitioning (BSP) tree is constructed that represents the shadow volume of the polygons facing it. As each polygon's contribution to a light source's shadow volume is determined, the polygon's shadowed and lit fragments are computed by filtering it down the shadow volume BSP tree. The polygonal scene with its computed shadows can be rendered with any polygon-based visible-surface algorithm. Since the shadow volumes and shadows are computed in object space, they can be used for further analysis of the scene. Pseudocode is provided, along with pictures and timings from an interactive implementation.
Real-time rendering of trimmed surfaces
Authors: Rockwood Alyn , Heaton Kurt , Davis Tom
Published: November 2005

Rational tensor product surfaces, (Bézier, NURBS, Hermite, polynomial, etc.) are rendered in real-time by uniform faceting. The described methods are modular and can be balanced for optimal implementation on different hardware platforms. Discretization anomalies such as angularities, Mach banding, cracking etc. are avoided by tessellating the surface patches and segmenting the trimming curves based on the view.
Accurate color reproduction for computer graphics applications
Authors: Lindbloom Bruce J.
Published: November 2005

A method is presented for accurate color reproduction among a wide variety of display devices. The method is very general, in that it may be applied to virtually any color display device. Its generality has been demonstrated by application to color monitors, film recorders, electronic pre-press systems and color hardcopy devices. The algorithm has been used to accurately translate between device dependent and device independent color specifications and to translate from one device dependent color specification to another.The method separates the color reproduction process into two distinct components:
device characterization
, which accounts for the colorimetric properties of each class of display device, and
device calibration
, which accounts for local variations from one instance of a device to another.A
companded
RGB color space is introduced, which is used with trivariate parametric polynomial volumes (i.e. hyperpatches) to perform accurate color transformations.A color separation algorithm is presented which converts companded RGB to and from the subtractive printing colors (cyan, magenta, yellow, black) using gray component replacement.
Metamouse: specifying graphical procedures by example
Authors: Maulsby David L. , Witten Ian H. , Kittlitz Kenneth A.
Published: November 2005

Metamouse is a device enabling the user of a drawing program to specify graphical procedures by supplying example execution traces. The user manipulates objects directly on the screen, creating graphical tools where necessary to help make constraints explicit; the system records the sequence of actions and induces a procedure. Generalization is used both to identify the key features of individual program steps, disregarding coincidental events; and to connect the steps into a program graph, creating loops and conditional branches as appropriate. Metamouse operates within a 2D click-and-drag drafting package, and incorporates a strong model of the relative importance of different types of graphical constraint. Close attention is paid to user interface aspects, and Metamouse helps the user by predicting and performing actions, thus reducing the tedium of repetitive graphical editing tasks.
A two-view approach to constructing user interfaces
Authors: Avrahami Gideon , Brooks Kenneth P. , Brown Marc H.
Published: November 2005

This paper describes a system for constructing graphical user interfaces following a two-view paradigm: one view contains a textual representation of the interface in a special-purpose, "little" language, and the other view contains a direct manipulation, interactive editor for the user interface. The user interface can be edited in either view, and the changes are reflected in the other view. The language allows dialog boxes to be expressed in a simple and natural way, and has a well-defined mapping into the interactive editor. A base set of interactors is currently available, but the system can be easily extended with more interactors. We believe this approach to building user interfaces combines the advantages of the direct manipulation, WYSIWYG approach with the advantages of the textual, descriptive approach, and does not suffer from the limitations of either approach.
An efficient 3-D visualization technique for finite element models and other coarse volumes
Authors: Gallagher R. S. , Nagtegaal J. C.
Published: November 2005

We have developed a technique that extends existing 3-D result visualization methods for use with discretized volumes such as finite element models, where result values are only available at coarsely spaced points throughout the volume. It represents results as smooth isosurfaces within the volume for one or more result values, using visually continuous, bi-cubic polynomials.At each of the points where results are available, result gradients are calculated by a finite difference procedure. The result values and result gradients are used to obtain the location of and the tangents to the isosurfaces on lines connecting the result points. Continuous doubly curved surfaces and surface normals are constructed separately between these discrete isosurface points using bi-cubic polynomials. The isosurfaces are rendered with standard light-source shading and optional levels of translucency, surrounded by translucent free faces of the structure.The method generates isosurfaces on an element-by-element basis, without reference at display time to the behavior of neighboring elements. It is intended for high speed display-time processing of either static or varying isosurface values.
Computer graphics visualization for acoustic simulation
Authors: Stettner A. , Greenberg D. P.
Published: November 2005

Computer simulations can be used to generate the spatial and temporal data describing the acoustical behavior of performance halls, but typically the analytical results are difficult to assimilate and compare. By using computer graphics to display the multi-dimensional data, substantially greater amounts of information than that conveyed by standard techniques can be communicated to the designer. This allows designs of different acoustical spaces to be tested, evaluated, and compared.An example comparing the acoustical behavior of three different concert halls demonstrates these techniques and allows for the simultaneous assimilation of much of the information necessary to evaluate the acoustical nature of a space. The use of three-dimensional images, color, animation and abstract representation allows for the comprehension of the complex results of a scientific simulation. Specifically, the simultaneous display of particular icons familiar to the discipline enabled the simultaneous presentation of up to twelve parameters.From a more general point of view, the procedures demonstrate how computer graphics can be utilized for the portrayal of multi-dimensional time dependent data. The visualization techniques are potentially useful for the display of three-dimensional vector fields in many scientific and design applications.
Three dimensional Terrain modeling and display for environmental assessment
Authors: Kaneda K. , Kato F. , Nakamae E. , Nishita T. , Tanaka H. , Noguchi Takao
Published: November 2005

A technique for compositing computer generated images of buildings and background images created from aerial photographs is described. The aerial photo data are mapped onto a terrain model based on cartographic data. The technique can be used to pre-evaluate visual impact of large scale construction by means of not only still images but also animations.The technique can be briefly described as follows: 1) an accurate, three-dimensional terrain model is created based on cartographic data. 2) a hierarchy of aerial photo data at various resolutions is mapped onto the terrain model as a texture. 3) the height of trees is taken into account in regions near the viewpoint. 4) allowing intersections of terrain models with constructions facilitates geometric adjustments and shadowing.
Hypertexture
Authors: Perlin K. , Hoffert E. M.
Published: November 2005

We model phenomena intermediate between shape and texture by using space-filling applicative functions to modulate density. The model is essentially an extension of procedural solid texture synthesis, but evaluated throughout a volumetric region instead of only at surfaces.We have been able to obtain visually realistic representations of such shape+texture (
hypertexture
) phenomena as hair, fur, fire, glass, fluid flow and erosion effects. We show how this is done, first by describing a set of base level functions to provide basic texture and control capability, then by combining these to synthesize various phenomena.Hypertexture exists within an intermediate region between object and not-object. We introduce a notion of
generalized boolean shape operators
to combine shapes having such a region.Rendering is accomplished by
ray marching
from the eye point through the volume to accumulate opacity along each ray. We have implemented our hypertexture rendering algorithms on a traditional serial computer, a distributed network of computers and a coarse-grain MIMD computer. Extensions to the rendering technique incorporating refraction and reflection effects are discussed.
Rendering fur with three dimensional textures
Authors: Kajiya J. T. , Kay T. L.
Published: November 2005

We present a method for rendering scenes with fine detail via an object called a
texel
, a rendering primitive inspired by volume densities mixed with anisotropic lighting models. This technique solves a long outstanding problem in image synthesis: the rendering of furry surfaces.
A Ray tracing algorithm for progressive radiosity
Authors: Wallace J. R. , Elmquist K. A. , Haines E. A.
Published: November 2005

A new method for computing form-factors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemi-cube algorithm to determine form-factors. However, sampling problems inherent in the hemi-cube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the form-factor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived form-factors and ray traced form-factors are presented.
A general two-pass method integrating specular and diffuse reflection
Authors: Sillion F. , Puech C.
Published: November 2005

We analyse some recent approaches to the global illumination problem by introducing the corresponding
reflection operators
, and we demonstrate the advantages of a two-pass method. A generalization of the system introduced by Wallace
et al.
at Siggraph '87 to integrate diffuse as well as specular effects is presented. It is based on the calculation of
extended form-factors
, which allows arbitrary geometries to be used in the scene description, as well as refraction effects. We also present a new sampling method for the calculation of form-factors, which is an alternative to the
hemi-cube
technique introduced by Cohen and Greenberg for radiosity calculations. This method is particularly well suited to the extended form-factors calculation. The problem of interactive display of the picture being created is also addressed by using hardware-assisted projections and image composition to recreate a complete specular view of the scene.
A characterization of ten rasterization techniques
Authors: Gharachorloo N. , Gupta S. , Sproull R. F. , Sutherland I. E.
Published: November 2005

With widespread use of raster scan displays and the ever-increasing desire for faster interactivity, higher image complexity, and higher resolution in displayed images, several techniques have been proposed for rasterizing primitive graphical objects. This paper characterizes the performance of these techniques and shows how they evolve for more complex images on higher resolution displays. This characterization will not only show the strengths and deficiencies of existing rasterization techniques, but will also reveal new architectures for future raster graphics systems.
Separable image warping with spatial lookup tables
Authors: Wolberg G. , Boult T. E.
Published: November 2005

Image warping refers to the 2-D resampling of a source image onto a target image. In the general case, this requires costly 2-D filtering operations. Simplifications are possible when the warp can be expressed as a cascade of orthogonal 1-D transformations. In these cases, separable transformations have been introduced to realize large performance gains. The central ideas in this area were formulated in the 2-pass algorithm by Catmull and Smith. Although that method applies over an important class of transformations, there are intrinsic problems which limit its usefulness.The goal of this work is to extend the 2-pass approach to handle arbitrary spatial mapping functions. We address the difficulties intrinsic to 2-pass scanline algorithms: bottlenecking, foldovers, and the lack of closed-form inverse solutions. These problems are shown to be resolved in a general, efficient, separable technique, with graceful degradation for transformations of increasing complexity.
Virtual environments and interactivity: windows to the future
Authors: Conn Coco , Lanier Jaron , Minsky Margaret , Fisher Scott , Druin Allison
Published: November 2005

I really apologize. I promised everyone I would come out wearing the data suit, but it just slipped my mind and I never got around to it. Actually Marvin Minsky was saying that the thing to do would be to come out with nothing on because that would be the perfect interface to the computer. So I kind of shunned the whole thing off at that point.We just heard Nicholas Negroponte ask us -- "how do we communicate with computers?" Well, that's why this panel is here today. We'll be discussing virtual environments and interactivity with some of the people who have been doing a lot of work in this field. I was interviewing a lot of people last night at the parties about virtual environments and I realized that everyone has their own idea of what their virtual environment will be. Some want to interact more, others less. Some want little people running around on the screen bringing them all sorts of messages or images. We'll be hearing about a lot of different types of interactivity on our panel today.I'd like to point out that Margaret's slide should also include the MIT Media Lab as well as UNC.I'm going to show some tapes and do some talking later on so I'd like start of by introducing Jaron Lanier. He's the guy with the dreadlocks you've seen at the Silicon Graphics booth. He has an amazing collection of musical instruments from all over the world and when he plays them, he transports you to other times and other places. He's a designer of programming languages and he started VPL, the company that brought you the glove, Jaron.
Computer art - an oxymoron? Views from the mainstream
Authors: Spencer D. , Rand H. , Huffman K. , Pearlstein P. , Riley B. , Stapp Will , Rainer Vivian
Published: November 2005

Hello. My name is Dorothy Spencer, and this is a special session entitled
Computer Art - An Oxymoron? Views from the Mainstream.
Before I introduce the panel members I want to tell you two things briefly about the session. First I'm going to tell you what the session does not focus on, and to do that I'm going to read from the SIGGRAPH 89 Show daily that came out this morning. So, for any of you that read it and came here expecting to hear museum curators, gallery owners and artists discuss the evolution of computer art as a means for artistic expression, you can go away now; we're not going to do it.What we are going to do is talk about the fact that computer generated imagery --- although it's been around for several decades, the mainstream art world has been slow to acknowledge it as a viable medium for the creation of fine art. There have been few computer art exhibitions and even fewer reviews. Like photography, is computer art going to take three-quarters of a century before it's accepted into the mainstream?Is it partially the fault of the artist? Are artists too wrapped up in the technological processes to be concerned with the aesthetic results?Does the majority of the artists using the computer not participate in regular juried shows because they feel their work is not understood?Does the technology need to be understood before the work can be judge aesthetically?These are just a few of the questions that we hope to discuss this morning and hopefully we'll have answers for. After each panelist has made his or her presentation, we'll let the panelists respond to each other's remarks before we let you people loose with questions and answers.My first panelist is Harry Rand. He's curator of painting and sculpture at the Museum of American Art in Washington, D.C. He'll be followed by Kathy Huffman, She's the director of the Institute of Contemporary Art, Boston. Followed by Philip Pearlstein, internationally-known artist and former professor of painting at Brooklyn College; Bob Riley, curator of media art, San Francisco Museum of Modern Art; Will Stapp, curator of photography of the National Portrait Gallery; and Vivian Rainer, art critic for the New York Times. We hope you enjoy the session. Thank you.
Design for interactive performance in a virtual laboratory
Authors: Wang Chu P. , Koved Lawrence , Dukach Semyon
Published: November 2005

In recent years, a number of research groups have implemented various versions of virtual world concept [2, 4, 6, 7]. A common thread among these virtual worlds is a direct manipulation user interface paradigm based on a glove device with the position and orientation of the hand registered by a tracking device. To explore this paradigm, a new project at IBM Research was started in 1989 to build a virtual laboratory for scientists and engineers. Our first step is to integrate the glove and space tracking devices with the real time graphics on a graphics superworkstation. A simple bouncing ball virtual world has been created to test underlying software and fine tune interactive performance.Our initial emphasis is placed on understanding the limitations of various system components and getting the best interactive performance from the system. With current state of technology, the glove and tracking devices can generate much more data than the graphics update process can utilize. Both the rendering process and the processes handling the device serial ports are CPU intensive. Our first design problem is how to distribute the processing and match the incoming data rates of input devices with the update rate of the graphics. After a new position from the tracker is received by the graphics, it is displayed only at the next frame update time giving the appearance that the hand image always lags behind the motion of the real hand. Our second design problem is to use techniques to compensate for this inherent lag time. This abstract describes the specific approaches we use to solve these problems and some useful insight gained in experimenting with lag time reduction by position prediction.