bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Basis for Shikimate-Binding Specificity ofHelicobacter pyloriShikimate Kinase
Authors: Cheng Wen-Chi , Chang Yu-Ning , Wang Wen-Ching
Published: November 2005

Shikimate kinase (EC 2.7.1.71) catalyzes the specific phosphorylation of the 3-hydroxyl group of shikimic acid in the presence of ATP. As the fifth key step in the shikimate pathway for aromatic amino acid biosynthesis in bacteria, fungi, and plants, but not mammals, shikimate kinase represents an attractive target for the development of new antimicrobial agents, herbicides, and antiparasitic agents. Here, we report the 1.8-Å crystal structure ofHelicobacter pylorishikimate kinase (HpSK). The crystal structure shows a three-layer alpha/beta fold consisting of a central sheet of five parallel β-strands flanked by seven α-helices. An HpSK-shikimate-PO4complex was also determined and refined to 2.3 Å, revealing induced-fit movement from an open to a closed form on substrate binding. Shikimate is located above a short 310helix formed by a strictly conserved motif (GGGXV) afterβ3. Moreover, several highly conserved charged residues including Asp33 (in a conserved DT/SD motif), Arg57, and Arg132 (interacting with shikimate) are identified, guiding the development of novel inhibitors of shikimate kinase.
The
Pseudomonas aeruginosa
Proteome during Anaerobic Growth
Authors: Wu Manhong , Guina Tina , Brittnacher Mitchell , Nguyen Hai , Eng Jimmy , Miller Samuel I.
Published: November 2005

Isotope-coded
affinity tag analysis and two-dimensional gel electrophoresis followed
by tandem mass spectrometry were used to identify
Pseudomonas
aeruginosa
proteins expressed during anaerobic growth. Out of the
617 proteins identified, 158 were changed in abundance during anaerobic
growth compared to during aerobic growth, including proteins whose
increased expression was expected based on their role in anaerobic
metabolism. These results form the basis for future analyses of
alterations in bacterial protein content during growth in various
environments, including the cystic fibrosis
airway.
CONSTRAINTS ON WEAKLY MIXED STERILE NEUTRINOS IN THE LIGHT OF SNO SALT PHASE AND 766.3 Ty KamLAND DATA
Authors: DEV S. , KUMAR SANJEEV
Published: November 2005

The possibility of flavor transitions into sterile neutrinos (accompanying the dominant LMA transitions) in the solar boron neutrino flux has been examined in a scenario proposed by Hollanda and Smirnov to overcome some generic problems of the pure LMA scenario. It is found that the most recent SNO salt phase solar neutrino data and the KamLAND 766.3 Ty spectral data, allow for a significant sterile presence in the solar boron neutrino flux reaching the earth.
TWO-DIMENSIONAL DESCRIPTION OF D-DIMENSIONAL STATIC BLACK HOLES WITH POINTLIKE SOURCES
Authors: CADONI MARIANO , MIGNEMI SALVATORE
Published: November 2005

We derive two-dimensional (2D) solutions of a generic dilaton gravity model coupled with matter, which describe D-dimensional static black holes with pointlike sources. The equality between the mass M of the D-dimensional gravitational solution and the mass m of the source can also be preserved at the level of the 2D gravity model.
NEUTRON ELECTRIC DIPOLE MOMENT AND FLAVOR CHANGING INTERACTIONS IN SUPERSYMMETRIC THEORIES
Authors: CHO GI-CHOL , HABA NAOYUKI , HONDA MINAKO
Published: November 2005

Supersymmetric contributions to the neutron electric dipole moment (EDM) are studied by taking account of the flavor changing interactions. We found that the gluino contribution is sensitive to the flavor changing interaction. Enhancement of neutron EDM via flavor mixing effects is possible when the squark mass difference between the different generations is sizable. As an example, the results of the SUSY SU (5) GUT with right-handed neutrinos are briefly discussed.
SEMICLASSICAL EXPANSIONS, THE STRONG QUANTUM LIMIT, AND DUALITY
Authors: ISIDRO JOSÉ M.
Published: November 2005

We show how to complement Feynman's exponential of the action so that it exhibits a ℤ2 duality symmetry. The latter illustrates a relativity principle for the notion of quantum versus classical.
INFLATION AT THE MAXIMA OF SYMMETRIC POTENTIALS
Authors: GERMÁN G. , DE LA MACORRA A.
Published: November 2005

We construct a two-stage inflationary model which can accommodate early inflation at a scale Λ1 as well as a second stage of inflation at Λ2 with a single scalar field ϕ. We use a symmetric potential, valid in a frictionless world, in which the two inflationary periods have exactly the same scale, i.e. Λ1 = Λ2. However, we see today Λ1 ≫ Λ2 due to the friction terms (expansion of the universe and interaction with matter). These type of models can be motivated from supergravity. Inflation occurs close to the maxima of the potential. As a consequence both inflations are necessarily finite. This opens the interesting possibility that the second inflation has already or is about to end. A first inflation is produced when fluctuations displace the inflaton field from its higher maximum rolling down the potential as in new inflation. Instead of rolling towards a global minimum the inflaton approaches a lower maximum where a second inflation takes place.
SECTOR OF THE 2++ MESONS: OBSERVATION OF THE TENSOR GLUEBALL
Authors: ANISOVICH V. V. , MATVEEV M. A. , SARANTSEV A. V. , NYIRI J.
Published: November 2005

Data of the Crystal Barrel and L3 collaborations clarified essentially the situation in the 2++ sector in the mass region up to 2400 MeV, demonstrating the linearity of (n, M2) trajectories, where n is the radial quantum number of a quark–antiquark state with mass M. We discuss these data and show that there exists a superfluous state for the (n, M2) trajectories: a broad resonance f2(2000). We pay special attention to the reactions [Formula: see text] in the mass region 1990–2400 MeV where, together with f2(2000), four relatively narrow resonances are seen: f2(1920), f2(2020), f2(2240), f2(2300). We analyze the branching ratios of all these resonances and show that only the decay couplings of the broad state f2(2000) → π0π0, ηη, ηη′ satisfy relations inherent in the glueball decay.
LARGE MIXING FROM SMALL: PSEUDO-DIRAC NEUTRINOS AND THE SINGULAR SEE-SAW
Authors: STEPHENSON G. J. , GOLDMAN T. , MCKELLAR B. H. J. , GARBUTT M.
Published: November 2005

If the sterile neutrino mass matrix in an otherwise conventional see-saw model has a rank less than the number of flavors, it is possible to produce pseudo-Dirac neutrinos. In a two-flavor, sterile rank 1 case, we demonstrate analytic conditions for large active mixing induced by the existence of (and coupling to) the sterile neutrino components. For the three-flavor, rank 1 case, "3+2" scenarios with large mixing also devolve naturally as we show by numerical examples. We observe that, in this approach, small mass differences can develop naturally without any requirement that masses themselves are small. Additionally, we point out that significant three-channel mixing and limited experimental resolution can combine to produce extracted two-channel mixing parameters at variance with the actual values.
A KNOT MODEL SUGGESTED BY THE STANDARD ELECTROWEAK THEORY
Authors: FINKELSTEIN ROBERT J.
Published: November 2005

We attempt to go beyond the standard electroweak theory by replacing SU (2) with its q-deformation: SU q(2). This step introduces new degrees of freedom that we interpret as indicative of nonlocality and as a possible basis for a solitonic model of the elementary particles. The solitons are conjectured to be knotted flux tubes labeled by the irreducible representations of SU q(2), an algebra which is not only closely related to the standard theory but also plays an underlying role in the description of knots. Each of the four families of elementary fermions is conjectured to be represented by one of the four possible trefoils. The three individual fermions belonging to any family are then assumed to occupy the three lowest states in the excitation spectrum of the trefoil for that family. One finds a not unreasonable variation of q among the lepton and quark families. The model in its present form predicts a fourth generation of fermions as well as a neutrino mass spectrum. The model may be refined depending on whether or not the fourth generation is found.
A NEW REGULARIZED LINEAR DISCRIMINANT ANALYSIS METHOD TO SOLVE SMALL SAMPLE SIZE PROBLEMS
Authors: CHEN WEN-SHENG , YUEN PONG C. , HUANG JIAN
Published: November 2005

This paper presents a new regularization technique to deal with the small sample size (S3) problem in linear discriminant analysis (LDA) based face recognition. Regularization on the within-class scatter matrix Sw has been shown to be a good direction for solving the S3 problem because the solution is found in full space instead of a subspace. The main limitation in regularization is that a very high computation is required to determine the optimal parameters. In view of this limitation, this paper re-defines the three-parameter regularization on the within-class scatter matrix [Formula: see text], which is suitable for parameter reduction. Based on the new definition of [Formula: see text], we derive a single parameter (t) explicit expression formula for determining the three parameters and develop a one-parameter regularization on the within-class scatter matrix. A simple and efficient method is developed to determine the value of t. It is also proven that the new regularized within-class scatter matrix [Formula: see text] approaches the original within-class scatter matrix Sw as the single parameter tends to zero. A novel one-parameter regularization linear discriminant analysis (1PRLDA) algorithm is then developed. The proposed 1PRLDA method for face recognition has been evaluated with two public available databases, namely ORL and FERET databases. The average recognition accuracies of 50 runs for ORL and FERET databases are 96.65% and 94.00%, respectively. Comparing with existing LDA-based methods in solving the S3 problem, the proposed 1PRLDA method gives the best performance.
LOCAL AND RECOGNIZABLE HEXAGONAL PICTURE LANGUAGES
Authors: DERSANAMBIKA K. S. , KRITHIVASAN K. , MARTIN-VIDE CARLOS , SUBRAMANIAN K. G.
Published: November 2005

In this paper we consider hexagonal arrays on triangular grids and introduce hexagonal local picture languages and hexagonal tiling systems defining hexagonal recognizable picture languages, motivated by an analogous study of rectangular arrays by Giammarresi and Restivo. We also introduce hexagonal Wang tiles to define hexagonal Wang systems (HWS) as a formalism to describe hexagonal picture languages. It is noticed that the family of hexagonal picture languages defined by hexagonal Wang systems and the family recognized by hexagonal tiling systems coincide. Analogous to hv-domino systems describing rectangular arrays, we define xyz-domino systems and prove that recognizable hexagonal picture languages are characterized as projections of xyz-local picture languages.
Game technology extends its reach
Authors: Westman Hans
Published: November 2005

Expanding on the subject of games, which we have covered in many recent issues, we are continuing the theme with an article on how components of video game technology are being used more widely than just developing product for entertainment.
Web-based learning fills a need
Authors: Varnum Susan
Published: November 2005

One of the great things about attending ACM SIGGRAPH is education. Whether about hardware, software, artistic styles, techniques or the people who pioneered them, everyone is there to learn. Pursuing a traditional education outside of SIGGRAPH is a challenge that most industry professionals will agree is daunting. I am convinced that help has finally arrived in the form of a completely new style of instruction for Miami International University of Art & Design (MIU): Web-based learning. The Art Institutes' MIU now offers an on-line master of fine arts (M.F.A.) in computer animation.
TUGS—a tool for teaching computer graphics
Authors: Clevenger John , Chaddock Rick , Bendig Roger
Published: November 2005

One of the best methods of teaching students about the principles underlying computer graphics systems is to have them develop an implementation of a "graphics pipeline" supporting modeling, viewing, and rendering operations. When completed, such an implementation represents a sophisticated package capable of producing complex images. However, these complex images typically cannot be generated until at or very near the completion of the project. We describe a tool called TUGS which has been developed to support the incremental development of a complex graphics system and which provides the ability to produce complex images early in the development process.TUGS is a complete graphics modeling and rendering system built from a highly-modularized set of primitive operations. Students can replace individual pieces of the TUGS system with their own implementations, while retaining use of the remaining TUGS routines. This allows incremental development of a complete system, while at the same time providing the ability to generate complete images. It also provides a vehicle for selective consideration of the many issues involved in modeling and rendering systems; those areas deemed most important can be assigned to students for implementation, while TUGS can be relied on to provide compatible implementations for the others. TUGS also includes a substantial collection of support routines to help reduce the "overhead" incurred in implementation efforts. These include command input parsing, 3D transformations, vector and matrix algebra operations, metafile storage, and support for device-independent low-level graphics, as well as many others.
1991 SIGGRAPH Educators' Slide Set
Authors: Cunningham Steve
Published: November 2005

SIGGRAPH'91 and its fixst-ever educators' program is also accompanied by the first SIGGRAPH Educators' Slide Set. This set is intended to provide instructors with sets of slides that support common subjects in computer graphics courses at all levels. In this first year, we are pleased to cover three topics that should be of interest to instructors at many levels and in many subject areas. The areas are outlined below.Interested instructors are encouraged to contact the editor if they have or are planning to prepare instructional slides on an area of computer graphics. We would like to continue to provide educational resources for computer graphics. This year marks the first educators' slide set, but we do not want it to be the last!
Computer graphics in Computing Curriculum 1991
Authors: Cunningham Steve
Published: November 2005

Computer graphics has not been treated as an important subject in computer science curriculum recommendations throughout the history of the ACM curriculum recommendations. A new report from the current ACM/IEEE-CS Joint Curriculum Task Force, entitled "Computing Curricula 1991" [6], is intended to provide curriculum recommendations for baccalaureate programs in areas of computing encompassed by ACM and IEEE-CS, replacing such recommendations as Curriculum 78 [2] and the 1983 IEEE-CS model program [4]. How does computer graphics fare in this report, and what are the implications of the report for computer graphics developments in computing curricula?Overall, computer graphics comes out fairly well in these recommendations. The report specifically recommends both computer graphics and human-cemputer interaction topics in the core curriculum. This partially reflects the Ohlson recommendations from SIGGRAPH's Education Committee [5] and is vastly better than Curriculum 78, which ignored computer graphics almost entirely. However, as we shall see, the core content of computer graphics and human-computer interaction is quite weak, and the Task Force seems to have had some question about how they should be worked into core courses. Advanced courses in both computer graphics and human-computer interaction are also explicitly suggested in the report. A description of a very standard elective computer graphics course is included in the report. The report concludes with summaries of some sample curricula, and the elective computer graphics course is listed in most of them. However, none of these include the human-computer interaction elective.
Unbiased sampling techniques for image synthesis
Authors: Kirk David , Arvo James
Published: November 2005

We examine a class of adaptive sampling techniques employed in image synthesis and show that those commonly used for efficient anti-aliasing are statistically biased. This bias is dependent upon the image function being sampled as well as the strategy for determining the number of samples to use. It is most prominent in areas of high contrast and is attributable to early stages of sampling systematically favoring one extreme or the other. If the expected outcome of the entire adaptive sampling algorithm is considered, we find that the bias of the early decisions is still present in the final estimator. We propose an alternative strategy for performing adaptive sampling that is unbiased but potentially more costly. We conclude that it may not always be practical to mitigate this source of bias, but as a source of error it should be considered when high accuracy and image fidelity are a central concern.
A comprehensive physical model for light reflection
Authors: He Xiao D. , Torrance Kenneth E. , Sillion François X. , Greenberg Donald P.
Published: November 2005

A new general reflectance model for computer graphics is presented. The model is based on physical optics and describes specular, directional diffuse, and uniform diffuse reflection by a surface. The reflected light pattern depends on wavelength, incidence angle, two surface roughness parameters, and surface refractive index. The formulation is self consistent in terms of polarization, surface roughness, masking/shadowing, and energy. The model applies to a wide range of materials and surface finishes and provides a smooth transition from diffuse-like to specular reflection as the wavelength and incidence angle are increased or the surface roughness is decreased. The model is analytic and suitable for Computer Graphics applications. Predicted reflectance distributions compare favorably with experiment. The model is applied to metallic, nonmetallic, and plastic materials, with smooth and rough surfaces.
A global illumination solution for general reflectance distributions
Authors: Sillion Françis X. , Arvo James R. , Westin Stephen H. , Greenberg Donald P.
Published: November 2005

A general light transfer simulation algorithm for environments composed of materials with arbitrary reflectance functions is presented. This algorithm removes the previous practical restriction to ideal specular and/or ideal diffuse environments, and supports complex physically based reflectance distributions, This is accomplished by extending previous two-pass ray-casting radiosity approaches to handle non-uniform intensity distributions, and resolving all possible energy transfers between sample points. An implementation is described based on a spherical harmonic decomposition for encoding both bidirectional reflectance distribution functions for materials, and directional intensity distributions for illuminated surfaces. The method compares favorably with experimental measurements.
A rapid hierarchical radiosity algorithm
Authors: Hanrahan Pat , Salzman David , Aupperle Larry
Published: November 2005

This paper presents a rapid hierarchical radiosity algorithm for illuminating scenes containing large polygonal patches. The algorithm constructs a hierarchical representation of the form factor matrix by adaptively subdividing patches into subpatches according to a user-supplied error bound. The algorithm guarantees that all form factors are calculated to the same precision, removing many common image artifacts due to inaccurate form factors. More importantly, the algorithm decomposes the form factor matrix into at most
O(n
) blocks (where
n
is the number of elements). Previous radiosity algorithms represented the element-to-element transport interactions with
n
2
form factors. Visibility algorithms are given that work well with this approach. Standard techniques for shooting and gathering can be used with the hierarchical representation to solve for equilibrium radiosities, but we also discuss using a brightness-weighted error criteria, in conjunction with multigridding, to even more rapidly progressively refine the image.
Interactive behaviors for bipedal articulated figures
Authors: Phillips Cary B. , Badler Norman I.
Published: November 2005

We describe techniques for interactively controlling bipedal articulated figures through kinematic constraints. These constraints model certain behavioral tendencies which capture some of the characteristics of human-like movement, and give us control over such elements as the figures' balanced and stability. They operate in near real-time, so provide behavioral control for interactive manipulation. These constraints form the basis of an interactive motion-generation system that allows the active movement elements to be layered on top of the passive behavioral constraints.
A differential compiler for computer animation
Authors: Denber Michel J. , Turner Paul M.
Published: November 2005

A program for the real-time display of computer animation on a bit-mapped raster display is presented. The differential compiler performs temporal domain image data compression using frame replenishment coding on successive frames of animation stored in memory as bitmaps and saves only the differences. A small run-time interpreter then retrieves and displays the differences in real-time to create the animated effect. This results in a significant reduction in storage requirements, and allows animation on general purpose computers which would otherwise be too slow or have insufficient memory. Frame creation is both device and method independent. An animation environment supports interactive editing capabilities, reconstructing any arbitrary desired frame for later modification. Frames can be added, modified, or deleted, and the animated sequence can be viewed at any point during the session. The compiler is automatically called as needed; its operation is transparent to the user. The compiler is described in detail, both in terms of data compression and the requirements of interactive animation editing.
Real time design and animation of fractal plants and trees
Authors: Oppenheimer Peter E.
Published: November 2005

The goal of science is to understand why things are the way they are. By emulating the logic of nature, computer simulation programs capture the essence of natural objects, thereby serving as a tool of science. When these programs express this essence visually, they serve as an instrument of art as well.This paper presents a fractal computer model of branching objects. This program generates pictures of simple orderly plants, complex gnarled trees, leaves, vein systems, as well as inorganic structures such as river deltas, snow flakes, etc. The geometry and topology of the model are controlled by numerical parameters which are analogous to the organism's DNA. By manipulating the
genetic
parameters, one can modify the geometry of the object in real time, using
tree based
graphics hardware. The random effects of the environment are taken into account, to produce greater diversity and realism. Increasing the number of significant parameters yields more complex and evolved species.The program provides a study in the structure of branching objects that is both scientific and artistic. The results suggest that organisms and computers deal with complexity in similar ways.
A simple model of ocean waves
Authors: Fournier Alain , Reeves William T.
Published: November 2005

We present a simple model for the surface of the ocean, suitable for the modeling and rendering of most common waves where the disturbing force is from the wind and the restoring force from gravity.It is based on the Gerstner, or Rankine, model where particles of water describe circular or elliptical stationary orbits. The model can easily produce realistic waves shapes which are varied according to the parameters of the orbits. The surface of the ocean floor affects the refraction and the breaking of waves on the shore. The model can also determine the position, direction, and speed of breakers.The ocean surface is modeled as a parametric surface, permitting the use of traditional rendering methods, including ray-tracing and adaptive subdivision. Animation is easy, since time is built into the model. The foam generated by the breakers is modeled by particle systems whose direction, speed and life expectancy is given by the surface model.To give designers control over the shape of the ocean, the model of the overall surface includes multiple trains of waves, each with its own set of parameters and optional stochastic elements. The overall "randomness" and "short-crestedness" of the ocean is achieved by a combination of small variations within a train and large variations between trains.Rendered examples of oceans waves generated by the model are given and a 10 second animation is described.
A fast shaded-polygon renderer
Authors: Swanson Roger W. , Thayer Larry J.
Published: November 2005

Image rendering is the performance bottleneck in many computer-graphics systems today because of its computation-intensive nature. Described here is a one-chip VLSI implementation of a shaded-polygon renderer which provides an affordable solution to the bottleneck. The chip takes advantage of a unique extension to Bresenham's vector drawing algorithm [1] to interpolate four axes (for Red, Green, Blue and Z) across a polygon, in addition to the X and Y values. Its inherent accuracy and ease of high-speed hardware implementation distinguish this new algorithm from interpolation with incrementing fractions (DDA).This chip was designed as part of a workstation primarily for mechanical engineering CAD applications. The pipelining and internal bandwidth possible on the chip allows rendering speeds of over twelve-thousand, 1000-pixel, shaded polygons per second, suitable for interactive manipulation of solids. Described in this paper is the derivation of the new algorithm and its implementation in a pipelined, polygon-rendering chip.
Free-form deformation of solid geometric models
Authors: Sederberg Thomas W. , Parry Scott R.
Published: November 2005

A technique is presented for deforming solid geometric models in a free-form manner. The technique can be used with any solid modeling system, such as CSG or B-rep. It can deform surface primitives of any type or degree: planes, quadrics, parametric surface patches, or implicitly defined surfaces, for example. The deformation can be applied either globally or locally. Local deformations can be imposed with any desired degree of derivative continuity. It is also possible to deform a solid model in such a way that its volume is preserved.The scheme is based on trivariate Bernstein polynomials, and provides the designer with an intuitive appreciation for its effects.
An adaptive subdivision method for surface-fitting from sampled data
Authors: Schmitt Francis J M , Barsky Brian A. , Du Wen-hui
Published: November 2005

A method is developed for surface-fitting from sampled data. Surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of given data points. In our case, the data is obtained from a real object using an automatic three-dimensional digitizing system. The method is based on an adaptive subdivision approach, a technique previously used for the design and display of free-form curved surface objects. Our approach begins with a rough approximating surface and progressively refines it in successive steps in regions where the data is poorly approximated. The method has been implemented using a parametric piecewise bicubic Bernstein-Bézier surface possessing G
1
geometric continuity. An advantage of this approach is that the refinement is essentially local reducing the computational requirements which permits the processing of large databases. Furthermore, the method is simple in concept, yet realizes efficient data compression. Some experimental results are given which show that the representation constructed by this method is faithful to the original database.
A montage method: the overlaying of the computer generated images onto a background photograph
Authors: Nakamae Eihachiro , Harada Koichi , Ishizaki Takao , Nishita Tomoyuki
Published: November 2005

A system of computer programs has been established to generate high quality montage image of considerable usefulness in architectural simulation which combine computer-generated images and photographed background pictures.Traditionally, there are two methods of creating architectural montages: (1) an artist paints new buildings onto a background scene usually generated photographically, and (2) a three-dimensional scale model is created to simulate the whole landscape, and this model is then photographed. The montage method described here combines aspects of both traditional montage methods with significant improvement in accuracy and reduction of time and cost of preparation. Specifically, a digitized photograph is used as a background scene onto which is superimposed a 3D computer-generated image of a new building. The outstanding points of the new method are:(i) The shading and shadows of each computer generated image are calculated with higher accuracy, (ii) the fog effect is taken into account, and (iii) a new anti-aliasing technique improves the quality of the final montage image.
Two bit/pixel full color encoding
Authors: Campbell Graham , DeFanti Thomas A. , Frederiksen Jeff , Joyce Stephen A. , Leske Lawrence A. , Lindberg John A. , Sandin Daniel J.
Published: November 2005

Realism in computer graphics typically requires using 24 or more bits/pixel to generate an image. This paper describes a method developed by the authors called "Color Cell Compression" or "CCC" that preserves at least a limited animation and local update capability yet yields extraordinary-looking color images in approximately two bits/pixel independent of image complexity. Three intermediate methods of compressing images to six, four and three bits/pixel respectively are also described. The CCC encoding process for a 640 × 480 image averages 11 seconds on a VAX 11/750, however, the CCC method does permit real-time decoding of these images using software look-up tables and conventional display hardware. The three intermediate methods may also be decoded in real time but have the added advantage of requiring only 3-4 seconds for encoding on a VAX 11/750.
Creating highly-interactive and graphical user interfaces by demonstration
Authors: Myers Brad A. , Buxton William
Published: November 2005

It is very time-consuming and expensive to create the graphical, highly-interactive styles of user interfaces that are increasingly common. User Interface Management Systems (UIMSs) attempt to make the creation of user interfaces easier, but most existing UIMSs cannot create the low-level interaction techniques (pop-up pull-down and fixed menus, on-screen "light buttons", scroll-bars, elaborate feedback mechanisms and animations, etc.) that are frequently used. This paper describes Peridot, a system that automatically creates the code for these user interfaces while the designer
demonstrates
to the system how the interface should look and work. Peridot uses rule-based inferencing so no programming by the designer is required, and Direct Manipulation techniques are used to create Direct Manipulation interfaces, which can make full use of a mouse and other input devices. This allows extremely rapid prototyping of user interfaces.
Ray tracing complex scenes
Authors: Kay Timothy L. , Kajiya James T.
Published: November 2005

A new algorithm for speeding up ray-object intersection calculations is presented. Objects are bounded by a new type of extent, which can be made to fit convex hulls arbitrarily tightly. The objects are placed into a hierarchy. A new hierarchy traversal algorithm is presented which is efficient in the sense that objects along the ray are queried in an efficient order.Results are presented which demonstrate that our technique is several times faster than other published algorithms. Furthermore, we demonstrate that it is currently possible to ray trace scenes containing hundreds of thousands of objects.
Ray tracing parametric surface patches utilizing numerical techniques and ray coherence
Authors: Joy Kenneth I. , Bhetanabhotla Murthy N.
Published: November 2005

A new algorithm for ray tracing parametric surface patches is presented. The method uses quasi-Newton iteration to solve for the ray/surface intersection and utilizes ray-to-ray coherence by using numerical information from adjoining rays as initial approximations to the quasi-Newton algorithm. Techniques based upon object space subdivision are used to insure convergence to the correct interesection point. Examples are given of the use of the algorithm in scenes containing Bézier surface patches. Results show that a significant number of ray/surface intersections on these parametric surface patches can be found using very few iterations, giving a significant computational savings.
What makes virtual systems a reality
Authors: Mamaghani Farid
Published: November 2005

If posed as a question, one possible answer to the title is: "sufficient resources." Given enough resources, sometimes referred to as infinite dollars, it is plausible that one can realize a life-like virtual environment, or the ultimate simulation system. For most of us, however, the fact remains that resources (time, money, processing power) are limited. Our objective then becomes to engineer solutions that satisfy the intended use of the product while remaining within bounds of the resource constraints. As simple as this focus may seem, it is often lost to two factors (1) getting caught up in the media hype of virtual reality and losing sight of the application and context, and (2) the inability to strike a realistic balance between affordable technology and the envisioned end product, i.e., the inability to come to terms with trade-offs.To prevent unanticipated disappointments, we need a solid understanding of the context and application of a simation system before getting carried away with the glamour of technology. This paper provides a top level examination of the complex issues associated with development and production of synthetic environments, and highlights some key trade-off elements.
Digital art
Authors: Prince Patric D.
Published: November 2005

Digital art is everywhere changing our perceptions of what art is and what it will become. As technological expression has developed as a new language, certain concerns have arisen indicating the degree to which society understands the technology.In the mid 1960s, when computer-mediated art was first shown publicly, one of the first concerns voiced by critics and viewers alike was, "but is it art?" The issue centered around the role of the technology in the art making process. Thirty years later this question is still the basis of the most frequently asked questions about creative expression that uses technology. Next came concerns about the issue of originality and the role of the technology. Which is the more important or most original: the digital data held in the memory of the computer or the realization of that data in the form of an artifact or art experience? In addition, an issue that was discussed by theorists and artists involved the separation of the creative act from the processes involved in realizing expression. Should artists control every aspect of the creation of their work? Should artists learn to program or can they rely on commercially-available instructions to the computer system?With the development of scanners capable of transforming any photographic medium into the digital realm, a frequently-voiced current concern revolves around the protection of intellectual property rights. Is it morally or legally ethical to scan in or copy someone else's work to use or incorporate into a new work of art? Aligned with this issue is concerns about the ownership of work that requires collaboration, or joint publishing.These digitally-related issues are frequently debated by the artists, critics and viewers of technological work and become even more interesting as interactivity-related concepts enter into the arena. When the artist becomes a conductor of ideas between the art work or experience, the viewer and the technology, when there is no one firm end to a story, when the viewer chooses his or her final version of an art work, when viewers become participants in the art making process, the answers to these questions become more complex and even more pertinent to adding to our understanding of digital expression.
Interactive teaching modules for computer graphics
Authors: Naiman Avi C.
Published: November 2005

We are developing a suite of interactive modules for teaching introductory computer graphics, using a library we have built to support such efforts. The modules provide explanations of fundamental concepts, tutorial demonstrations of basic techniques and interactive control of the parameters used in and execution of high level representations of elementary algorithms. The modules are used in laboratory sessions to supplement formal lectures. Here, we present our philosophy in building the library and modules, discuss the lessons we have learned in our initial implementation and outline our future plans.
Standards pipeline
Authors: Carson George S.
Published: November 2005

This is the first in a series of Standards Pipeline articles concerning important "de-facto" or "public" specifications rather than formal standards. Paula Womack and John Schimpf of SGI contributed the material on which this article is based.
Japan's view of flat panel displays
Authors: Andrews David
Published: November 2005

Japan owns 85 percent of the flat panel market. Who owns the rest? Who cares?!Japan, however, was not the driving force behind the technologies --- the majority of the contribution came from engineers from America, Britain, India and a handful of other countries. No, as usual, Japan added the manufacturing know-how, the vast investment and the tenacity required to take an emerging technology to market.Until now, liquid crystal displays (LCD) have occupied center stage. Small screens with fairly low resolution, patchy, inaccurate color reproduction, LCDs have been relegated to the lowly word processing and spreadsheet arenas. But what is it that Japan has in mind for the industry in the near future?
New developments for virtual model displays
Authors: McDowall Ian E. , Bolas Mark T.
Published: November 2005

This article introduces two new technology developments in the field of virtual model displays (VMD). Projection-based stereo systems have typically only been able to produce a single head-tracked image and have been constrained to non-adjustable surfaces.The first new technology, the Duo, allows
two
simultaneous and individually head-tracked stereo pairs to be displayed. This brings the virtual models to life, as two people can now share the workspace by pointing at the model and sharing virtual props to manipulate the model just as if it were sitting in front of them. The motion of either viewer does not impact the view of the other.The second new development in the field of VMDs is the ability to adjust the angle of the projection surface to provide a natural workspace depending on the application and associated virtual models.
Interactive three-dimensional holographic displays
Authors: Lucente Mark
Published: November 2005

Computer graphics is confined chiefly to flat images. Images may look three-dimensional (3D), and sometimes create the illusion of 3D when displayed, for example, on a stereoscopic display [16, 13, 12]. Nevertheless, when viewing an image on most display systems, the human visual system (HVS) sees a flat plane of pixels. Volumetric displays can create a 3D computer graphics image, but fail to provide many visual depth cues (e.g. shading texture gradients) and cannot provide the powerful depth cue of overlap (occlusion). Discrete parallax displays (such as lenticular displays) promise to create 3D images with all of the depth cues, but are limited by achievable resolution. Only a real-time electronic holographic ("holovideo") display [11, 6, 8, 7, 9, 21, 22, 20, 2] can create a truly 3D computer graphics image with all of the depth cues (motion parallax, ocular accommodation, occlusion, etc.) and resolution sufficient to provide extreme realism [13]. Holovideo displays promise to enhance numerous applications in the creation and manipulation of information, including telepresence, education, medical imaging, interactive design and scientific visualization.The technology of electronic interactive three-dimensional holographic displays is in its first decade. Though fancied in popular science fiction, only recently have researchers created the first real holovideo systems by confronting the two basic requirements of electronic holography: computational speed and high-bandwidth modulation of visible light. This article describes the approaches used to address these problems, as well as emerging technologies and techniques that provide firm footing for the development of practical holovideo.
Augmented reality
Authors: Elvins T. Todd
Published: November 2005

The fledgling field of wearable computers, where augmented reality (AR) technologies will play a critical role, recently attracted 400 enthusiasts to MIT for the Wearables Computer Symposium. (Editor's note:See Joan Truckenbrod's symposium review later in this issue.) The well-established ACM UIST Conference, held the following week, gathered only half that number. I was intrigued by this phenomenon and decided to learn more about AR. The most up-to-date reference is the August 1997 issue of the MIT Press journalPresence: Teleoperators and Virtual Reality[4] which is dedicated to describing state-of-the-art AR (abstracts are under the "Science and Technology" category athttp://mitpress.mit.edu/ journals.tcl). Distilled from the August issue ofPresenceand a few other sources, the following article gives a quick introduction to AR.AR, sometimes calledmediated reality,has an interesting past and a bright future. It will probably surprise no one that Ivan Sutherland, the father of interactive computer graphics, is also credited with inventing AR. In 1968 Sutherland built a head-mounted display (HMD) with monochrome monitors and mirrors. The half-silvered mirrors enabled the observer to see through the computer graphics display into the real world. That was 30 years ago. It seems likely that 30 years (or less) from now some people will choose to be constantly on-line via lightweight non-obtrusive glasses capable of dynamically compositing or blending high-resolution stereo 3D graphics with a view of the real world.
Computer-aided industrial design
Authors: Westin Stephen H.
Published: November 2005

Centuries ago, craftsmen made objects to their own design. A single person was generally responsible for both the function and the appearance of a tool or device. With the Industrial Revolution, design became specialized; design and production were handled by different people. Often design was dictated by the needs of efficient manufacturing. As engineering advanced, design became more involved and specialized, straying farther and farther from the intuition and experience that had guided craftsmen for centuries. Product appearance was in danger of being dominated by engineering considerations.In the 1930s, the field of industrial design was born, led by Raymond Loewy, Walter Dorwin Teague and others. These sought to specialize design still further by hiring someone to create the visual appearance of a product. The premise was that a company could make its products more sellable (i.e., make more money) by investing in the visual appearance of its products.In automotive design, style was initially the province of a few expensive coachbuilders: the wealthy could have a custom-styled car, much as today they can wear one-of-a-kind clothes from a famous designer. In parallel with the birth of industrial design for other products like radios and railway engines, Harley Earl started the Art and Color Department at General Motors. This group sought to improve the appearance of GM vehicles, as well as to keep the GM brands distinct as they migrated to shared internal body structures; they effectively brought designer style to ready-to-wear clothing. GM's success in the '20s and '30s led other manufacturers to follow suit.Computer-aided design has followed a similar path: first it was used to aid manufacturing; later, for functional, engineering design. Only in the last decade has it penetrated aesthetic industrial design. Computer-aided industrial design (CAID) is CAD adapted and specialized for aesthetic design. From a designer's point of view, CAD is for the pocket-protector brigade, while CAID is for the creative.My own exposure to CAID has been over the last 13 years from within the design organization of a car manufacturer. This vantage point has advantages and disadvantages: a car-maker's design environment certainly isn't typical of industrial design as a whole, but car-makers have been innovators and drivers of CAID technology.
3D graphics hardware
Authors: Baum Dan
Published: November 2005

What can we expect to see in 3D graphics hardware in the coming years? What markets will drive next generation designs? Where will PC graphics be in the year 2000? These questions are frequently debated by users, application vendors and manufacturers of 3D graphics hardware. In this article, I will offer some views and opinions on these and related questions. First, I will briefly review a bit of the history of hardware accelerated graphics. Next, I will give an overview of the current state of graphics hardware. Finally, I will discuss what directions graphics hardware will be going in the future.
Digital copy protection and SIGGRAPH public policy WWW pages
Authors: Ellis Bob
Published: November 2005

This column covers a policy issue I haven't discussed before: digital copy protection. I also have an update on plans for SIGGRAPH's Public Policy Web pages and a procedural item.
Professional chapters
Authors: Lang Scott , Cleary Colleen
Published: November 2005

This month's column features our regular chapters wrap-up and an article by the Mexico City Chapter Newsletter Editor, Gonzalo León. We hope you enjoy it.
Feynmann diagrams and spreading illusions
Authors: West Thomas G.
Published: November 2005

"Schwinger's quantum electrodynamics and Feynmann's may have been mathematically the same, but one was conservative and the other revolutionary. One extended an existing line of thought. The other broke with the past decisively enough to mystify its intended audience. One represented an ending: a mathematical style doomed to be fatally overcomplex. The other, for those willing to follow Feynmann into a new style of visualization, served as a beginning. Feynmann's style was risky, even megalomaniacal." [1]
Women in computer graphics
Authors: Machover Carl , Branum Alyce
Published: November 2005

In this gender-free age, we sometimes forget how difficult it was for women to break into most fields, and computer graphics was certainly no exception. Today, we have hundreds of women in the computer graphics field holding high positions in industry (e.g. Carol Bartz, President of AutoDesk) and in academia (e.g. Judy Brown, University of Iowa). However, in the pre-SIGGRAPH days of the late '50s, '60s and early '70s, this was not the case. The woman in technology with the highest visibility was Commander Grace Hopper, but then one was hard pressed to identify others. The Society for Information Displays honored Frances Rice Darn, an Army display scientist, by creating the Frances Rice Darn Memorial Award.Alyce Branum, guest author of this Pioneers column, is among our early women computer graphics pioneers. She began work for me at Information Displays in 1969, having come from a technical staff position with Bunker Ramo. She later went on to work in computer graphics positions at Xynetics, Digital Equipment Corporation, Summagraphics and IBM. Alyce talks about her early experiences, and those of some of the other women computer graphics pioneers.