bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards image realism with interactive update rates in complex virtual building environments
Authors: Airey John M. , Rohlf John H. , Brooks Frederick P.
Published: November 2005

Two strategies, pre-computation before display and adaptive refinement during display, are used to combine interactivity with high image quality in a virtual building simulation. Pre-computation is used in two ways. The hidden-surface problem is partially solved by automatically pre-computing potentially visible sets of the model for sets of related viewpoints. Rendering only the potentially visible subset associated with the current viewpoint, rather than the entire model, produces significant speedups on real building models. Solutions for the radiosity lighting model are pre-computed for up to twenty different sets of lights. Linear combinations of these solutions can be manipulated in real time. We use adaptive refinement to trade image realism for interactivity as the situation requires. When the user is stationary we replace a coarse model using few polygons with a more detailed model. Image-level linear interpolation smooths the transition between differing levels of image realism.
Acceleration techniques for progressive refinement radiosity
Authors: Recker Rodney J. , George David W. , Greenberg Donald P.
Published: November 2005

The progressive refinement radiosity method provides a means for computing the global illumination of an environment in time proportional to the size of the environment. Additionally, the method supplies a
sequence
of solutions that monotonically converge to a high-quality result, allowing it to be used for interactive applications that deliver "near real-time" updates as the computation proceeds. This paper presents two methods for accelerating the radiosity method. First, the traditional hemi-cube algorithm is modified to accelerate the expensive form-factor calculation. Second, the radiosity method is parallelized across a coarse-grain network, and the efficiency of the parallel system is discussed.
Real time radiosity through parallel processing and hardware acceleration
Authors: Baum Daniel R. , Winget James M.
Published: November 2005

This paper describes a novel implementation of the progressive refinement radiosity algorithm. Algorithm performance is greatly enhanced using the capabilities of a multiprocessor graphics workstation. Hemi-cube item buffers are produced using the graphics hardware while the remaining computations are performed in parallel on the multiple host processors. Speedups of a factor of 40 or more over the equivalent software implementation are observed. Load balancing issues are discussed and a system performance model is developed based on actual results.Additionally, a new user interface scheme is presented where the radiosity calculations and walk-through tasks are separated. At each new iteration, the radiosity algorithm automatically updates colors used by the viewing program via shared memory while simultaneously obtaining hints on where to further refine the solution.
Automatic illustration of 3D geometric models: lines
Authors: Dooley Debra , Cohen Michael F.
Published: November 2005

A system for the automatic generation of line illustrations of three dimensional sculptured objects is described. In particular, an enriched vocabulary of lines are defined which provide a means to impart meaning to visual representations of complex objects. Particular attention is paid to how the end conditions of individual segments effect how they are drawn. A graphical interface is described for creating illustration rules which translate the geometric description into the final drawing. Some algorithmic details are provided for implementation and preliminary results are presented.
Real time spline curves from interactively sketched data
Authors: Banks Michael , Cohen Elaine
Published: November 2005

Hand-sketching is a particularly attractive solution to providing an intuitive design interface for modeling. The goal is to reduce the data collected from the input strokes and to construct a curve that faithfully represents the sketched data. This paper presents a new approach to interactive realtime handsketching in two or three dimensions and is-based on the new approach to general spline datafitting presented in [10,8,9].The goal of our approach is to obtain approximating curves with reasonable accuracy at real-time interactive speeds, and at the same time significantly reduce in the number of coefficients for the curve representation over the original data representation. The approach taken here to obtain realtime interaction is to reduce the data incrementally using new local algorithms while the data is still being sketched.
Interactive techniques for implicit modeling
Authors: Bloomenthal Jules , Wyvill Brian
Published: November 2005

Recent research has demonstrated the usefulness of implicit surfaces for modeling geometric objects. The interactive design of such surfaces has not, however, received the same attention as has the design of parametric surfaces. Principally this is due to the difficulty of controlling the shape of implicit surfaces while displaying the changes quickly enough for use within an interactive design environment. This paper describes progress towards interactive control of implicit surfaces and introduces new techniques useful to the designer.
Rational hypersurface display
Authors: Bajaj Chanderjit L.
Published: November 2005

Algorithms are presented for polygonalizing implicitly defined, quadric and cubic hypersurfaces in
n
≥ 3 dimensional space and furthermore displaying their projections in 3D. The method relies on initially constructing the rational parametric equations of the implicitly defined hypersurfaces, and then polygonalizing these hypersurfaces by an adaptive generalized curvature dependent scheme. The number of hyperpolygons used are optimal, in that they are the order of the minimum number required for a smooth Gouraud like shading of the hypersurfaces. Such hypersurface projection displays should prove useful in scientific visualization applications. The curvature dependent polygonal meshes produced, should also prove very useful in finite difference and finite element analysis programs for multi-dimensional domains.
Tracing interactive 3D graphics programs
Authors: Dunwoody J. Craig , Linton Mark A.
Published: November 2005

The two goals of graphics performance analysis are to characterize application workloads and to understand how systems perform under these workloads. We have developed a set of tools to help achieve these goals. TGEN is a tracing program that intercepts graphics library calls from an application program and records them in a file. TPROF is a profiler that interprets a trace file and computes workload statistics. TBENCH is a portable performance measurement tool that executes a trace file on a graphics system and measures the resulting update time. In this paper, we describe these tools and give examples of their use.
Control of a virtual actor: the roach
Authors: McKenna Michael , Pieper Steve , Zeltzer David
Published: November 2005

We have developed a virtual environment system which supports multiple simulations, including virtual actors. These actors exhibit motor behavior in response to activity in the environment. We present an example actor, whose low-level behavior is modeled after physiological analyses of cockroach motor behavior. The
sensori-motor
activity of our roach is generated by a hierarchical control structure. Coupled oscillators generate basic gait patterns, which are modified by reflexes feeding in from the environment. Stepping and stance are executed by kinematic motor programs, which move the legs and body. The
reactive
level associates motor behavior with events in the virtual environment, to simulate perception and implement higher level behaviors. The activity of the virtual actor is determined only when it is situated in the environment, and interacts with the user and other simulations.
Exploration and virtual camera control in virtual three dimensional environments
Authors: Ware Colin , Osborne Steven
Published: November 2005

This paper evaluates three distinct metaphors for exploration and virtual camera control in virtual environments using a six degree of freedom input device. The metaphors are "eyeball in hand", "scene in hand", and "flying vehicle control". These metaphors have been implemented and evaluated using an IRIS workstation and a Polhemus 3Space. The system has the capability to record the motion path followed during an exploration session and this can be recorded and played back to create a movie. Evaluation is through intensive structured interview sessions wherein subjects are required to complete a number of tasks involving three different "toy" environments. None of the metaphors is judged the best in all situations, rather the different metaphors each have advantages and disadvantages depending on the particular task. For example, "scene in hand" is judged to be good for manipulating closed objects, but is not good for moving through an interior; whereas "flying vehicle control" is judged the best for navigating through the interior, but is poor for moving around a closed object.
A real-time optical 3D tracker for head-mounted display systems
Authors: Wang Jih-fang , Chi Vernon , Fuchs Henry
Published: November 2005

In this paper, a new optical system for real-time, three-dimensional position tracking is described. This system adopts an "inside-out" tracking paradigm. The working environment is a room where the ceiling is lined with a regular pattern of infrared LEDs flashing under the system's control. Three cameras are mounted on a helmet which the user wears. Each camera uses a lateral effect photodiode as the recording surface. The 2D positions of the LED images inside the field of view of the cameras are detected and reported in real time. The measured 2D image positions and the known 3D positions of the LEDs are used to compute the position and orientation of the camera assembly in space.We have designed an iterative algorithm to estimate the 3D position of the camera assembly in space. The algorithm is a generalized version of the Church's method, and allows for multiple cameras with nonconvergent nodal points. Several equations are formulated to predict the system's error analytically. The requirements of accuracy, speed, adequate working volume, light weight and small size of the tracker are also addressed.A prototype was designed and built to demonstrate the integration and coordination of all essential components of the new tracker. This prototype uses off-the-shelf components and can be easily duplicated. Our results indicate that the new system significantly out-performs other existing systems. The new tracker provides more than 200 updates per second, registers 0.1-degree rotational movements and 2-millimeter translational movements, and processes a working volume about 1,000 ft
3
(10 ft on each side).
Gaze-directed volume rendering
Authors: Levoy Marc , Whitaker Ross
Published: November 2005

We direct our gaze at an object by rotating our eyes or head until the object's projection falls on the fovea, a small region of enhanced spatial acuity near the center of the retina. In this paper, we explore methods for encorporating gaze direction into rendering algorithms. This approach permits generation of images exhibiting continuously varying resolution, and allows these images to be displayed on conventional television monitors. Specifically, we describe a ray tracer for volume data in which the number of rays cast per unit area on the image plane and the number of samples drawn per unit length along each ray are functions of local retinal acuity. We also describe an implementation using 2D and 3D mip maps, an eye tracker, and the Pixel-Planes 5 massively parallel raster display system. Pending completion of Pixel-Planes 5 in the spring of 1990, we have written a simulator on a Stellar graphics supercomputer. Preliminary results indicate that while users are aware of the variable-resolution structure of the image, the high-resolution sweet spot follows their gaze well and promises to be useful in practice.
3D paint
Authors: Williams Lance
Published: November 2005

This paper advances a means by which the conventions and methods of digital "painting" and image manipulation programs can be extended into the third dimension, providing sculpting tools that are natural and appropriate for a restricted but very useful class of models. Attempts to approximate "drawing" in 3D do not necessarily involve computer graphics [Gregory71]. Efforts in this area are a subject of continuing graphics research [Schmandt82], [Sachs89]. The key to the approach undertaken in the work described here is the use of an unusual hardware technique for displaying video rasters as surfaces. With such a display, existing software for 2D graphics and image processing can be used, without modification, for creating and modifying three-dimensional surfaces. The resulting raster data can then be converted into conventional 3D databases for further processing and display. The aim of this research is to create consistent, unified methods for computer-assisted drawing, painting, modeling, and animation.
DDA
Authors: Guthery Scott B.
Published: November 2005

Graphical techniques are becoming more and more popular tools of applied statisticians and data analysts. This growing popularity is due both to the great intrinsic utility of graphic data displays and to the more widespread availability of graphic peripherals to computing systems. Since, however, graphical data analysis techniques are most valuable when used 1) interactively and 2) in conjunction with each other, rapidly shifting and expanding graphic display hardware and software technology has inhibited their full exploitation and utilization. The DDA language “workbench” attempts to minimize the amount of time which a statistician or data analyst must devote to language and machine-dependent considerations of graphical data analysis. This should enable him or her to concentrate on the development, investigation, and utilization of the graphical techniques themselves.
ARTSPEAK
Authors: Wardle Caroline
Published: November 2005

There is increasing interest in the use of computer graphics by artists. Graphics languages can be divided into several types, a common type being subroutine packages embedded in a high-level language. FORTRAN-coded EXPLOR (1) and ALGOL-coded PICTURES (2) fall into this category. Another approach is to implement a set of procedures designed for a particular application, an example of this being PDL-Picture Description Language(3,4) which is intended for the computer artist. However, there are few high-level languages designed to facilitate the production of computer art, a recent exception being ESP
3
(5) which combines line drawing with pattern recognition.

ARTSPEAK (6) was designed to simplify programming for the inexperienced (and probably mathematically-naive) user. The language is simple but has all the characteristics of a high-level language. It contains a powerful curve generating feature which encourages “free-hand” drawings as well as geometric drawings.
Picture naming and modification
Authors: Foley James D.
Published: November 2005

The purpose of this paper is to review and organize the basic concepts involved in naming and modifying images presented on a graphics display, and to indicate the advantages and disadvantages of the various techniques currently used by graphics languages. We will not consider the syntactic questions of how the semantic capabilities are presented to the language users. A number of extant graphics programming languages are categorized according to their naming and modification capabilities.
Methods for specifying display parameters in graphics programming languages
Authors: Thomas Elaine L.
Published: November 2005

A general purpose graphics programming language should provide a means for specifying not only the lines, characters, and/or surfaces which compose a picture but also parameters such as the intensity of a particular object in the picture and the relative position of one object with respect to another in the picture. This paper will address the manner in which graphics programming languages associate display parameters with display objects. The syntax of the particular graphics programming language will not be considered, nor will the capabilities of the display hardware with which the language is associated. Instead, the paper will concentrate on the semantics of display parameter specification.
Picture primitives in device independent graphics systems
Authors: Bergeron R. Daniel
Published: November 2005

Current device independent graphics systems define their graphical output primitives (picture primitives) in a very
ad hoc
manner. This paper identifies the approaches taken by some typical systems, suggests a formalization of the concept of a picture primitive, and proposes an implementation framework for a device independent graphics system.
The semantics of graphic input devices
Authors: Wallace Victor L.
Published: November 2005

All input devices for interactive computer graphics can be effectively modelled in programs by a small number of virtual input devices. By specifying an appropriate set of such virtual devices, the semantics of interactive input can be defined independently of the physical form of the devices. In the service of program portability, human factors adaptability, economy, and maximal use of terminal capability, a sufficient set of virtual devices is described.
The TV Turtle a Logo graphics system for raster displays
Authors: Lieberman Henry
Published: November 2005

Until recently, most computer graphics systems have been oriented toward the display of line drawings, continually refreshing the screen from a
display list
of vectors. Developments such as plasma panel displays and rapidly declining memory prices have now made feasible
raster
graphics systems, which instead associate some memory with each point on the screen, and display points according to the contents of the memory. This paper discusses the advantages and limitations of such systems. Raster systems permit operations which are not feasible on vector displays, such as reading directly from the screen as well as writing it, and manipulating two dimensional areas as well as vectors. Conceptual differences between programming for raster and vector systems are illustrated with a description of the author's
TV Turtle
, a graphics system for raster scan video display terminals. This system is imbedded in Logo, a Lisp-like interactive programming language designed for use by kids, and is based on Logo's
turtle geometry
approach to graphics. Logo provides powerful ideas for using graphics which are easy for kids to learn, yet generalize naturally when advanced capabilities such as primitives for animation and color are added to the system.
A device independent computer plotting system
Authors: Gujar Uday G.
Published: November 2005

This paper describes a computer plotting system which is completely device independent. The user can switch from one plotting device to another without any programming changes. The interface for adding new plotting devices is formalized and discussed. The addition of a new plotting device is completely transparent to the user; in fact, the old programs may be used to produce plots on the new device without any programming changes whatsoever.

The system was designed and implemented by the author in late 1971 and has been in use ever since (see Ref. 1). Several new plotting devices, real as well as pseudo, have been added successfully without affecting the users of the system.
An interpretive/interactive subroutine system for raster graphics
Authors: Garrett Michael T.
Published: November 2005

A subroutine package has been developed for a disk based raster scan graphics system which builds the entire image in random access memory so that each pixel is randomly addressable, greatly simplifying the image construction routines. A pseudo-display file is used with a subpicture library for structuring images. Interaction with user programs is handled by a single subroutine in which a simple interpretive language, a point stack and the ability to dynamically assign meanings to function buttons creates a powerful environment.
A language for two-dimensional digital picture processing
Authors: Wang Patrick Shen-Pei , Grosky William I.
Published: November 2005

A new system, that of matrix grammars, for two-dimensional pattern processing, is introduced. A hierarchy, induced on Chomsky's is found. Language operations such as union, catenation (row and column), Kleene's closure (row and column), and homomorphisms are investigated. It is found that the smallest class of these languages may serve as the class of regular arrays, which is defined as the smallest class of arrays closed under union, catenation (row and column) and Kleene's closure (row and column). Eight possible ways of defining a matrix language are discussed and it is suggested that one of them may lead to a normal form for matrix grammars. The method is advantageous over others on several points. Perhaps the most interesting of all is that it provides a compromise between sequential methods which take too much time for large arrays and parallel methods which usually take too much hardware for large arrays.
Interactive computer graphics and macromolecular structures
Authors: Bond Peter J.
Published: November 2005

In 1964 on Project MAC at MIT, Levinthal and Langridge first applied interactive computer graphics to molecular model building (1, 2). Since then a number of laboratories have developed computer graphics systems to suit their particular needs (3, 4, 5, 6).

I shall begin by describing the system that we have developed in the Princeton University Computer Graphics Laboratory during the past year to investigate macromolecular structures.
Large-scale numerical problems in biomedical studies
Authors: Greenfield H.
Published: November 2005

A review of on-going projects employing an interdisciplinary approach is presented. This approach is the applicability of computer graphics, fluid dynamics and numerical analysis techniques to hemodynamic problems in medicine. It has been shown to be feasible. The hemodynamic studies are the analysis of blood movement in prosthetic heart valves and the attempt to understand initiation and formation of atherosclerotic lesions. It is demonstrated that the Navier-Stokes equations of flow are amenable to descriptive solution by computer graphics and resulting examples of particular surface and perspective displays are presented. Comparison of computer graphics experiments with clinical findings are discussed.
Computer aided study of human locomotion
Authors: Kasvand T. , Quanbury A. O.
Published: November 2005

A subject walking in front of a coded background is photographed with a high speed movie camera. For greater accuracy, the camera is moved parallel to the subject at his walking speed. The successive film frames are analyzed by a flying spot scanner under computer control. The computer program determines the location of the camera using the background code and finds the position co-ordinates of marker dots placed over various points of interest on the subject's body and limbs. From the location of the marker dots the trajectories of the various limbs and joints can be obtained in graphical form, as well as data pertaining to joint velocities and angular displacements. It is felt that this information can have important clinical use for assessing walking disabilities and for measuring gait improvement in amputees.
Application of an interactive graphics system to the kinematic design of an artificial knee joint
Authors: Kaufman Roger E.
Published: November 2005

KINSYN is an interactive general purpose computer system for the kinematic synthesis and analysis of mechanisms. It is applicable to kinematics problems ranging from the synthesis of spacecraft antenna deployment mechanisms to the design of folding high chairs. Features of KINSYN have been described in several recent publications.

The results shown in this paper were obtained during the first two or three trial runs on KINSYN. Of course, extensive work would remain to be done in order to apply these techniques to a practical artificial limb design, Nonetheless, the fact that so much useful design data can be obtained so readily with the aid of KINSYN indicates that it could be a significant aid in a physiological limb development program.
Some problems associated with interactive graphics in computer mediated tutorials
Authors: Weber J. C. , Linden D. J. , Frayer W. W. , Hagamen W. D.
Published: November 2005

Whether one is talking about the verbal or graphic aspects of a computer mediated tutorial, there are two prime considerations. (1) How easy is it for the medical teacher to input the information? (2) How closely does the interaction with the student approximate a free format tutorial?

Our experience has gone through two distinct phases. For the first two years we worked with the IBM 1500 System and its associated language COURSEWRITER II (1). The 1500 has both a CRT with light pen and a random access, computer addressed, 35mm film strip projector.

For the past two years we have been working with APL/360 and an IBM 2741 Communications Terminal with no graphic capabilities. Using APL we have developed a new (author) programming language called ATS (A Tutorial System) (2,3,4).

Our purpose here today is to focus on the two aspects of a computer mediated tutorial already mentioned. Because of the nature of our personal experience, we would like to compare the problems (both the similarities and differences) associated with handling verbal and graphic input. The discussion will be divided into the following major topics. (1) A brief description of the 1500 System and our contributions to it.

This work has been documented previously. (2) Interfacing the medical author with the computer. (3) Providing the machine with the intelligence to handle free format interactions with the student. (4) A word about encoding verbal and graphic information.
Display requirements for the physician's office
Authors: Adams Gayle E. , Miller Owen W. , Dobbs Douglas H.
Published: November 2005

This paper presents a summary of the experience gained in operating a medical information system in a rural private physician's office. In particular, data is presented on this operational system which should be helpful to designers for defining the requirements of patient interactive devices.
A questionnaire
Authors: Lucido Anthony P.
Published: November 2005

Comments from the editors

To determine the current status of some of the work being done by our readers I have put together a questionnaire. The questionnaire itself will be found following this short note. I would appreciate hearing from all persons currently doing some work in the area of computer graphics, or from anyone wishing to contribute information on a system in use. I will try to put all responses together (assuming someone out there responds) and summarize what is being done, as indicated by the returned questionnaires.
The development of a dynamic interactive computer graphics research and educational support environment
Authors: Stocker Frederick R. , Johnson Gerald G. , McKinstry Herbert A.
Published: November 2005

The Pennsylvania State University Computation Center is currently performing research and development in providing an effective research and training support environment which enables a user, whether researcher or student, to become familiar with an available base of graphics hardware and software support and to proceed to original programming with confidence and effectiveness.The main consideration is to provide an interactive programming environment in which users can become self-sufficient in coping with both hardware operation and potential as well as effective utilization of software in a reasonably short period of time. Such users should not have to be computer graphics specialists to apply a graphics system to their fields of expertise. Users should be thoroughly trained to understand and handle an available hardware/software system in order to be better able to evaluate the potential system usage directly and effectively.This paper, together with a film, describes an approach developed at the Computation Center and tested and implemented in three offerings of a Computer Science advanced undergraduate course.
Wave
Authors: Robbins Fred E. , Green William G.
Published: November 2005

WAVE, an interactive color graphics software system for Waveform Analysis Visualization and Edification, is an evolving software interface between an Anagraph Color Graphics System, a CDC 6400/7600 computer configuration, and User Application programs coded in standard FORTRAN source language.WAVE, when mated with the user application modules provides a complete specialized interactive graphical analysis system. The system features:• Full interaction of user with program operation via keyboard/trackball inputs;• A large repertoire of viewing and display options for interactive selection;• Interactive storage and retrieval of displays and off-line or job-to-job capabilities available through magnetic tape;• A variety of methods for the retrieval of analytical information;• Automatic adjustment of scaling, centering, and other detailed viewing parameters to maximize user convenience;• Application program options displayed in user terminology to minimize learning time;• Modular construction to facilitate addition of new application modules.The WAVE program is readily modified to meet specialized user requirements. Several applications of the WAVE system are currently operational at the Ballistic Missile Defense Advanced Technology Center's (BMDATC) Advanced Research Center (ARC) in Huntsville, Alabama. The WAVE technique has been applied comprehensively to the problem of radar ambiguity analysis and clutter rejection. Other applications of WAVE are currently in progress or have been less comprehensively developed.
A graphics operating system
Authors: Koenigsberg Lawrence , Meads Jon A. , Shaw John , Thanhouser Ned , Vollum Steven
Published: November 2005

Stand alone graphic systems and time-shared graphics provide different benefits to a user. The same is true of refresh graphics and storage displays. An operating system is described which supports these combined modes through the integration of graphics into the operating system. Realization of the role of the system, generality, and flexibility were the major factors in the development of the system. The result is a computer graphic system providing high-level interactive graphics at a relatively low cost.
IMAGE
Authors: O'Brien C. D. , Bown H. G.
Published: November 2005

This paper addresses itself to the problems involved in programming an interactive computer graphics display. A list of graphical programming facilities considered necessary for an interactive graphic programming language is presented. An examination of several application programs, written in a variety of existing languages, revealed that many of these facilities are usually lacking.This paper presents the design of a new interactive graphics language 'IMAGE', developed specifically to satisfy the above criteria. The language places particular emphasis on providing a graphics application programmer the ability to program graphical interaction. The 'IMAGE' language utilizes the better features of several current graphic languages and combines these features with a unique interaction control structure. This OBJECT / ACTION control structure, the display picture description syntax and the hardware independent handling of input devices are the main features of the language, providing excellent graphical input response and drawing facilities. The device independent input / output structure permits the implementation of a portable language syntax, since there are no references to display hardware devices. All display references are performed through a virtual terminal. This paper contains a detailed description of the main features of the language and these features are illustrated in an example 'IMAGE' program.
On high-level programming systems for structured display programming
Authors: Giloi Wolfgang K.
Published: November 2005

The main topic of the paper is to introduce a concept for structured display programming in interactive computer graphics and to discuss the suitability of FORTRAN, ALGOL, PL/I, and APL as the host language for such a programming system. To this end, the interrelationship between picture structures, data structures, and language structures is first established. Based on the obtained conclusions, a model language for interactive display programming (GRIP) is introduced. The suitability of the above mentioned languages is discussed, and experiences with the implementation of the GRIP philosophy in some of these languages are communicated.
Efficient octree conversion by connectivity labeling
Authors: Tamminen Markku , Samet Hanan
Published: November 2005

We present an algorithm for converting from the boundary representation of a solid to the corresponding octree model. The algorithm utilizes an efficient new connected components labeling technique. A novelty of the method is the demonstration that all processing can be performed directly on linear quad and octree encodings. We illustrate the use of the algorithm by an application to geometric mine modeling and verify its performance by analysis and practical experiments.
A retrospective (Panel)
Authors: Dunn Robert M.
Published: November 2005

Graphics has been an industry for more than 15 years. Some workers trace its origins almost )0 years. The dramatic gains in silicon technology along with more highly developed understanding of the mathematics of graphics have transformed the architecture of computer graphic systems and produced a bewildering array of products and services.

This retrospective panel will try to put several key things in perspective. Dr. Alan Kay, recently of Atari Computer and currently an Apple Fellow, will characterize the role of graphics in the overall world of computing and information processing. Carl Machover of Machover Associates will trace the development of display technology and its employment in computer graphics systems. Dr. David Evan, Chairman of the Board of Evans and Sutherland will create the retrospective on our ability to produce realism in imagery. In turn Dr. Robert Sproull, Sutherland, Sutherland and Associates will trace the development of transformation that have found their way into silicon technology. Dr. James Foley, of George Washington University will track our progress in the technology of interaction, while Dr. Robin Forrest of the University of East Angela will trace geometric modeling and Dr. Ed Cattail, Director of Development at Lucasfilm will put our progress in animation in perspective.
Chap - a SIMD graphics processor
Authors: Levinthal Adam , Porter Thomas
Published: November 2005

Special purpose processing systems designed for specific applications can provide extremely high performance at moderate cost. One such processor is presented for executing graphics and image processing algorithms as the basis of a digital film printer. Pixels in the system contain four parallel components: RGB for full color and an alpha channel for retaining transparency information. The data path of the processor contains four arithmetic elements connected through a crossbar network to a tessellated scratchpad memory. The single instruction, multiple data stream (SIMD) processor executes instructions on four pixel components in parallel. The instruction control unit (ICU) maintains an activity stack for tracking block-structured code, using data-dependent activity flags for conditional disabling subsets of the ALUs. Nested loops and if-then-else constructs can be programmed directly, with the ICU disabling and reenabling ALUs on the basis of their individual status bits
.
Invisibility coherence for faster scan-line hidden surface algorithms
Authors: Crocker Gary A.
Published: November 2005

Invisibility coherence is a new technique developed to decrease the time necessary to render shaded images by existing scan-line hidden surface algorithms. Invisibility coherence is a technique for removing portions of a scene that are not likely to be visible. If a large portion of the scene is invisible, as is often the case in three-dimensional computer graphics, the processing time eliminated may be substantial. Invisibility coherence takes advantage of the observation that a minimal amount of processing needs to be done on objects (polygons, patches, or surfaces) that will be hidden by other objects closer to the viewer. This fact can be used to increase the efficiency of current scan-line algorithms, including both polygon-based and parametrically curved surface-based algorithms.

Invisibility coherence was implemented and tested with the polygon hidden surface algorithm for constructive solid geometry developed by Peter Atherton [1]. The use of invisibility coherence substantially increases the efficiency of this scan-line algorithm. Invisibility coherence should work as well or even better with other scan-line hidden surface algorithms, such as the Lane-Carpenter, Whitted, and Blinn algorithms for parametrically curved surfaces [2]., or the Watkins, Romney, and Bouknight algorithms for polygons [3, 4, 5].
The A -buffer, an antialiased hidden surface method
Authors: Carpenter Loren
Published: November 2005

The A-buffer (anti-aliased, area-averaged, accumulation buffer) is a general hidden surface mechanism suited to medium scale virtual memory computers. It resolves visibility among an arbitrary collection of opaque, transparent, and intersecting objects. Using an easy to compute Fourier window (box filter), it increases the effective image resolution many times over the Z-buffer, with a moderate increase in cost. The A-buffer is incorporated into the REYES 3-D rendering system at Lucasfilm and was used successfully in the “Genesis Demo” sequence in Star Trek II.
Beam tracing polygonal objects
Authors: Heckbert Paul S. , Hanrahan Pat
Published: November 2005

Ray tracing has produced some of the most realistic computer generated pictures to date. They contain surface texturing, local shading, shadows, reflections and refractions. The major disadvantage of ray tracing results from its point-sampling approach. Because calculation proceeds
ab initio
at each pixel it is very CPU intensive and may contain noticeable aliasing artifacts. It is difficult to take advantage of spatial coherence because the shapes of reflections and refractions from curved surfaces are so complex.

In this paper we describe an algorithm that utilizes the spatial coherence of polygonal environments by combining features of both image and object space hidden surface algorithms. Instead of tracing infinitesimally thin rays of light, we sweep areas through a scene to form “beams.” This technique works particularly well for polygonal models since for this case the reflections are linear transformations, and refractions are often approximately so.

The recursive beam tracer begins by sweeping the projection plane through the scene. Beam-surface intersections are computed using two-dimensional polygonal set operations and an occlusion algorithm similar to the Weiler-Atherton hidden surface algorithm. For each beam-polygon intersection the beam is fragmented and new beams created for the reflected and transmitted swaths of light. These sub-beams are redirected with a 4×4 matrix transformation and recursively traced. This beam tree is an object space representation of the entire picture.

Since the priority of polygons is pre-determined, the final picture with reflections, refractions, shadows, and hidden surface removal is easily drawn. The coherence information enables very fast scan conversion and high resolution output. Image space edge and texture antialiasing methods can be applied.
Trends in semiconductor hardware for graphics systems (Panel)
Authors: Fuchs Henry
Published: November 2005

During the next 5 - 10 years, text and graphic systems will tend to merge because of the demand for a more productive man/machine interface, failing memory costs and the availability of higher performance VLSI controllers. This panel will discuss video controllers, memory components and their architectures, graphic systems configurations and the evolution of enhanced system performance versus reduced system cost.
Microcomputer graphics (Panel)
Authors: Pearlmutter Howard
Published: November 2005

Ranging from home computers for entertainment and education to personal work-stations for design and presentation, microprocessor hardware spans the entire spectrum of graphic applications. Through live demonstrations of the latest and most popular hardware and software offerings, we hope to give you a feeling for the rapidly growing field of personal, “human scale” computing. The session will include a visual tour of the MacPaint package and the Quickdraw firmware on Apple's Macintosh personal computer, as well as brief demos of software for educational videogrames, low resolution typography and interactive, real-time animation.

Depending on audience questions, we might also take a look at issues and trends involved in mass marketing of software, personalization of technology and ownership of knowledge...and what the ramifications might be for the future of computer graphics and the human (-) computer dialogue.
Manipulating simulated objects with real-world gestures using a force and position sensitive screen
Authors: Minsky Margaret R.
Published: November 2005

A flexible interface to computing environments can be provided by gestural input. We describe a prototype system that recognizes some types of single-finger gestures and uses these gestures to manipulate displayed objects. An experimental gesture input device yields information about single finger gestures in terms of position, pressure, and shear forces on a screen. The gestures are classified by a “gesture parser” and used to control actions in a fingerpainting program, an interactive computing system designed for young children, and an interactive digital logic simulation.
Summed-area tables for texture mapping
Authors: Crow Franklin C.
Published: November 2005

Texture-map computations can be made tractable through use of precalculated tables which allow computational costs independent of the texture density. The first example of this technique, the “mip” map, uses a set of tables containing successively lower-resolution representations filtered down from the discrete texture function. An alternative method using a single table of values representing the integral over the texture function rather than the function itself may yield superior results at similar cost. The necessary algorithms to support the new technique are explained. Finally, the cost and performance of the new technique is compared to previous techniques.
The role and reality of graphics standards (Panel)
Authors: Warner James R.
Published: November 2005

Graphics standards are formally sanctioned guidelines for graphics programming. Just as ANSI standards provide FORTRAN programmers with a common ground among compilers, the role of graphics standards is to define a set of common procedures or subroutines for developing graphics applications. The primary objectives underlying graphics standards are program portability and a common methodology for application program development.

Graphic standards are clearly desirable and efforts to bring them about are well underway. Nevertheless, the role of graphics standards must be matched with the reality of software development environments.

A common problem faced by all standards committees is the very long lead time required to arrive at consensus. Most standards groups are staffed by volunteers, chartered to develop standards models around generally-accepted current professional practices. Often, this is a time-consuming process relying on compromise and diplomacy and hampered by long intervals between meetings.

As a result, standards inevitably lag behind the industry, where competitive hardware vendors play leapfrog with one another, pushing the state of the art. Much of the concern surrounding standards implementations stems from the low level of standards literacy in the graphics user community. Beyond a vague understanding of functionality, most graphics software shoppers have little understanding on the different levels of standards, how to measure a good implementation, and methods of programming efficiently using a graphics standards methodology. As a result, standards-based packages face the difficult challenge of balancing the theoretical world of standards with the down to-earth needs of application developers working against deadlines.

This session will measure the several standards proposals now in the ANSI pipeline against the requirements and literacy level of the buying public. The evolution of a standard through ANSI and the implications of certification procedures will be presented and discussed. The problems of implementing a graphics standard will also be discussed, along with the general buying criteria to follow when shopping for standards-based graphics software.
Texture synthesis for digital painting
Authors: Lewis John-Peter
Published: November 2005

The problem of digital painting is considered from a signal processing viewpoint, and is reconsidered as a problem of directed texture synthesis. It is an important characteristic of natural texture that detail may be evident at many scales, and the detail at each scale may have distinct characteristics. A “sparse convolution” procedure for generating random textures with arbitrary spectral content is described. The capability of specifying the texture spectrum (and thus the amount of detail at each scale) is an improvement over stochastic texture synthesis processes which are scalebound or which have a prescribed 1/f spectrum. This spectral texture synthesis procedure provides the basis for a digital paint system which rivals the textural sophistication of traditional artistic media. Applications in terrain synthesis and texturing computer-rendered objects are also shown.
GKS for imaging
Authors: Stoll Cliff
Published: November 2005

By adopting the Graphical Kernel System (GKS), groups who manipulate pixelated images can take advantage of device independent graphics without giving up the functions which have traditionally been hardware dependent. Most of these functions, including image I/O, zoom, pan, lookup table manipulation, and cursor reading, are supported within GKS; several other functions, such as the use of multiple image planes and multiple look up tables, are accomodated by the GKS Escape and the Generalized Drawing Primitive (GDP). Because GKS has powerful inquire capabilities, it's possible to tightly customize applications code to a particular hardware display device. The inquire functions also can be used by an applications program to determine the hardware display size and thus avoid resampling of a pixelated image.

GKS thoroughly separates applications programs from device- dependencies; however, device drivers must still be written. The time and effort of writing device drivers can be largely eliminated by using a single programmable device driver, which is tailored to each device by a GRAPHCAP configuration file, in much the same way as TERMCAP is used by Berkeley Unix implementations.
Nova*gks, a distributed implementation of the Graphical Kernel System
Authors: Waggoner Clinton N. , Tucker Charles , Nelson Christopher J.
Published: November 2005

NOVA*GKS is an implementation of the Draft International Standard Graphical Kernel System (GKS), built using a distributed architecture. The specifications for GKS present an implementor with many design tradeoff decisions. The implementors of NOVA*GKS have analyzed those tradeoffs and created a distributed design which allows users of the package to design applications which can perform efficiently on many different graphics hardware configurations.