bluuebunny/crossref_metadata_2025 huggingface dataset:
Technical implications of proposed graphics standards (Panel Session)
Authors: Straayer David , Bono Peter , Ehlers Richard , Enderle Gunter , Reed Theodore , Shuey David , Skall Mark , Sonderegger Elain , Wright Tom
Published: November 2005

This panel session is intended to present recent technical developments in the efforts to standardize computer graphics.

Several alternative approaches to 3-D standards will be presented and contrasted. The Virtual Device Metafile will be presented, as well as a proposed binding of the GKS standard to Fortran.

Presentations will be made by the following individuals:

Dr. Peter Bono is the chairman of the ANSI X3H3 technical committee developing standards for Computer Graphics Programming Languages, and will present the current status of the effort to adopt 2-D GKS as an International Standard and as an American National Standard.

Tom Wright will be available to respond to questions about the Programmer's Minimal Interface to Graphics (PMIG) proposal, and its current status as a new output level of the draft proposed American National Standard (dpANS) GKS.

Mark Skall will present a proposed binding of GKS to the Fortran Language. Mr. Skall will also discuss progress in the field of formal specification of graphics standards and developments in the establishment of conformance/certification procedures for implementations of GKS.

Theodore Reed will present the technical content of the Virtual Device Metafile (VDM) draft proposed American National Standard. Discussed will be the relationship of the VDM to GKS and to the yet to be proposed Virtual Device Interface. Specific functionality of the VDM will be discussed as will specific bindings of that functionality as a character set extension and as a binary format.

David Shuey will present an overview of the Programmer's Hierarchical Interface to Graphics (PHIGS) proposal. The PHIGS proposal is intended to support hierarchical structuring of graphics data, in contrast to the Core System and GKS proposals. This type of structure addresses highly interactive graphics applications which need to modify the presentation and the relationships within graphics data.

Richard Ehlers will present the attribute model of the PHIGS proposal and explore the relationship of attribute model to structured graphics data bases. Also, Mr. Ehlers will discuss the viewing and transformation implications of structured graphics data bases using examples.

Gunter Enderle is a member of the West German delegation to the International Standards Organization (ISO) Working Group on Computer Graphics. Herr Enderle will be discussing ISO proposals for the extension of the GKS standard from 2-D to 3-D functionality. Several such proposals have been made, including one by DIN (the official standards making body of the German Federal Republic) and a Norwegian proposal called IDIGS.

Elaine Sonderegger was a member of the ACM SIGGRAPH Graphics Standards Planning Committee, and is the ACM SIGGRAPH representative to ANSI X3H3. Ms. Sonderegger will contrast the 3-D functionality of the Core System, IDIGS, DIN proposed 3-D extensions, and PHIGS.
Computer graphic modeling of american sign language
Authors: Loomis Jeffrey , Poizner Howard , Bellugi Ursula , Blakemore Alynn , Hollerbach John
Published: November 2005

The essential grammatical information of American Sign Language (ASL) is conveyed through changes in the movement and spatial contouring of the hands and arms. An interactive computer graphic system is described for the analysis and modeling of sign language movement. This system consists of four components. The first component reconstructs actual movements in three dimensions and allows the user to interactively segment and transform the data for later analysis. The second component allows a user to interactively create synthetic signs by specifying angle functions in a jointed model. The third component provides a novel technique for manipulating movement quality independently of spatial path. The fourth component allows the building of complex stimuli and real-time stimulus sequencing for psycholinguistic experiments. The emphasis is on interactive techniques and data structures that allow analysis and modeling of the complex hand and arm movements of American Sign Language.
INCENSE
Authors: Myers Brad A.
Published: November 2005

Many modern computer languages allow the programmer to define and use a variety of data types. Few programming systems, however, allow the programmer similar flexibility when displaying the data structures for debugging, monitoring and documenting programs.
Incense
is a working prototype system that allows the programmer to interactively investigate data structures in actual programs. The desired displays can be specified by the programmer or a default can be used. The default displays provided by Incense present the standard form for literals of the basic types, the actual names for scalar types, stacked boxes for records and arrays, and curved lines with arrowheads for pointers. In addition to displaying data structures, Incense also allows the user to select, move, erase and redimension the resulting displays. These interactions are provided in a uniform, natural manner using a pointing device (
mouse
) and keyboard.
Graphical style towards high quality illustrations
Authors: Beach Richard , Stone Maureen
Published: November 2005

If there is to be widespread acceptance of computer generated images in areas traditionally served by graphic artists, these images must meet a high standard of quality. Document preparation systems are an application area that is gaining maturity in providing high-quality computer typeset documents. These systems exhibit a trend towards specifying the formatting information for a document separately from the body of the text. The goal is to have the document format designed by someone with expert knowledge of typography. Writers can then apply a format to their own work simply by indicating the semantic content of their text, such as the headings, paragraphs, or footnotes. The result is that a writer can produce properly typeset documents without learning the esthetics of typography. This paper extends this idea to encompass the illustrations in the text. We have developed a prototype system that uses a set of graphical style rules to define the design guidelines for the illustrations. The rules, called a
graphical style sheet,
can be used to control a uniform “look” over a set of illustrations, or to change the appearance of a particular illustration to reflect different publishing styles or different media. The prototype coordinates with an existing document preparation system and the combined systems were used to produce this paper. We conclude that this is a viable method for controlling image style for at least one class of illustrations. This approach contributes to image quality by providing a method for capturing knowledge of graphic arts standards, and for ensuring a consistent appearance of related illustrations within technical documentation.
A core graphics environment for teletext simulations
Authors: Dixon Douglas F.
Published: November 2005

The development of our graphics environment over the past year has been directed towards demonstrating the concept of broadcast teletext service, where pages of graphics and text are received in the home over existing television channels. We have developed a graphics editor, Radix, which uses an underlying Core graphics package to create teletext-compatible images. Radix is also used to display these images at arbitrary resolutions by scaling the graphics primitives, selecting the corresponding sizes of fonts and bitmaps, and then precisely adjusting the output video signal. The combination of powerful display hardware and a robust set of software tools has allowed us to rapidly prototype potential teletext features, and to provide these accurate simulations of teletext pages at any resolution. While this general graphics environment does impose some inefficiencies in running graphics applications, they are far outweighed by the ability to quickly respond to changing requirements.
Topologically reliable display of algebraic curves
Authors: Arnon Dennis S.
Published: November 2005

An algebraic curve is a set of points in the plane satisfying an equation
F(x,y)
= 0, where
F(x,y)
is a polynomial in x and y with rational number coefficients. The topological structure of an algebraic curve can be complicated. It may, for example, have multiple components, isolated points, or intricate self-crossings. In the field of Computer Algebra (Symbolic Mathematical Computation), algorithms for exact computations on polynomials with rational number coefficients have been developed. In particular, the cylindrical algebraic decomposition (cad) algorithm of Computer Algebra determines the topological structure of an algebraic curve, given
F(x,y)
as input. We describe methods for algebraic curve display which, by making use of the cad algorithm, correctly portray the topological structure of the curve. The running times of our algorithms consist almost entirely of the time required for the cad algorithm, which varies from seconds to hours depending on the particular
F(x,y)
.
Curve-fitting with piecewise parametric cubics
Authors: Plass Michael , Stone Maureen
Published: November 2005

Parametric piecewise-cubic functions are used throughout the computer graphics industry to represent curved shapes. For many applications, it would be useful to be able to reliably derive this representation from a closely spaced set of points that approximate the desired curve, such as the input from a digitizing tablet or a scanner. This paper presents a solution to the problem of automatically generating efficient piecewise parametric cubic polynomial approximations to shapes from sampled data. We have developed an algorithm that takes a set of sample points, plus optional endpoint and tangent vector specifications, and iteratively derives a single parametric cubic polynomial that lies close to the data points as defined by an error metric based on least-squares. Combining this algorithm with dynamic programming techniques to determine the knot placement gives good results over a range of shapes and applications.
Solid model input through orthographic views
Authors: Sakurai Hiroshi , Gossard David C.
Published: November 2005

This paper describes the results of basic studies on procedures for creating solid models of component geometry from two-dimensional orthographic projections. An interactive graphic program was developed to allow the input of three orthographic views of a component geometry by digitizing from a drawing. The views may contain straight lines and circular arcs, solid or dashed. No restrictions are placed on the order or direction of lines and arcs in any view. Using an extension of the Wesley-Markowski procedure, the program constructs a three-dimensional solid model of the object. When the projections are ambiguous, multiple solid models are produced. The solid model may contain planar, cylindrical, conical, spherical and toroidal surfaces. Topological information of the solid model is stored in a winged edge structure. Geometric information is stored as vertex coordinates and surface equations.

The procedure for 2D-3D conversion provides a powerful new method for manual input of solid models, a common interface to all turnkey graphics systems, and, properly integrated with existing technology for scanning of drawings, a powerful new method for acquisition of CAD/CAM data bases from existing drawings.

The procedure is described, examples of typical input and output are shown, and possible extensions are discussed.
Spatial input/display correspondence in a stereoscopic computer graphic work station
Authors: Schmandt Christopher
Published: November 2005

An interactive stereoscopic computer graphic workspace is described. A conventional frame store is used for three-dimensional display, with left/right eye views interlaced in video and viewed through PLZT shutter glasses. The video monitor is seen reflected from a half silvered mirror which projects the graphics into a workspace, into which one can reach and manipulate the image directly with a “magic wand”. The wand uses a magnetic six degree-of-freedom digitizer. In an alternative configuration, a graphics tablet was placed within the workspace for input intensive tasks.
Three dimensional computer graphics for craniofacial surgical planning and evaluation
Authors: Vannier Michael W. , Marsh Jeffrey L. , Warren James O.
Published: November 2005

The understanding of complex craniofacial deformities has been aided by high resolution computed tomography. Nonetheless, the planar format limits spatial comprehension. Reconstruction of fully three-dimensional bony and soft tissue surfaces from high resolution CT scans has been accomplished by a level slicing edge detector coupled to a hidden surface processor without perspective depth transformation. This method has clarified aberrant anatomy, facilitated surgical planning and improved quantitative postoperative evaluation in more than 200 clinical cases. Advanced computer aided design techniques, originally developed for the manufacture of military aircraft, have been applied to the planning and evaluation of craniofacial procedures as well. This allows the application of interactive digital graphic technology to surgical patient management.
Design of solids with free-form surfaces
Authors: Chiyokura Hiroaki , Kimura Fumihiko
Published: November 2005

We propose a unified method of generating a wide range of three dimensional objects from polyhedra to solids with free-form surfaces. Modeling systems for polyhedra and systems for free-form surfaces have been developed independently in the past because of the difference in their underlying theory and practices. However, this is not desirable for a designer. So in this paper, we have shown a method in which a wide range of shapes are generated in one system by using local modifications. Local modifications are procedures used to change the shape of solids locally. The construction and the modification of three dimensional shapes by these procedures are natural and easy for a designer in many cases. The implementation of these procedures in a computer is easy and their execution does not require much time.

Our method to construct a solid with free-form surfaces consists of following three phases. 1) A solid which serves as a basis of free-form shape design is generated by local modifications. Edges of this solid are straight lines but its faces are not necessarily flat planes. 2) From this model, a curve model which adequately represents the characteristics of a free-form shape is generated. 3) Surface equations interpolating over the curve model are generated.

We have made a geometric modeling system MODIF. Using this system, a complicated solid with free-form surfaces can be designed easily. MODIF can generate color shaded pictures and cutter path data for making a real object model by NC machining tool.
An inexpensive scheme for calibration of a colour monitor in terms of CIE standard coordinates
Authors: Cowan William B.
Published: November 2005

The Commission Internationale d'Eclairage system of colorimetry is a method of measuring colours that has been standardized, and is widely used by industries involved with colour. Knowing the CIE coordinates of a colour allows it to be reproduced easily and exactly in many different media. For this reason graphics installations which utilize colour extensively ought to have the capability of knowing the CIE coordinates of displayed colours, and of displaying colours of given CIE coordinates. Such a capability requires a function which transforms video monitor gun voltages (RGB colour space) into CIE coordinates (XYZ colour space), and vice versa. The function incorporates certain monitor parameters. The purpose of this paper is to demonstrate the form that such a function takes, and to show how the necessary monitor parameters can be measured using little more than a simple light meter. Because space is limited, and because each user is likely to implement the calibration differently, few technical details are given, but principles and methods are discussed in sufficient depth to allow the full use of the system. In addition, several visual checks which can be used for quick verification of the integrity of the calibration are described.

The paper begins with an overview of the CIE system of colorimetry. It continues with a general discussion of transformations from RGB colour space to XYZ colour space, after which a detailed step-by-step procedure for monitor calibration is presented.
Interactive image query system using progressive transmission
Authors: Hill F. S. , Walker Sheldon , Gao Fuwen
Published: November 2005

There is a growing need for people to browse through files of images such as satellite or medical photos, to determine which ones warrant further examination. Users located at some distance from the image archive often must use slow transmission links such as telephone lines. If an image is scanned out line-by-line, top-to-bottom, the user must often wait too long to determine whether the image is of any use. Using the Progressive Transmission Method, however, images are encoded so that during transmission the entire display shows a rough version of the image in 'fat pixels'. If the user wishes to see more detail, additional data is sent and used to refine these pixels, until the exact original image is seen. We report here on extensions of this method to the rich color imagery found in remote-sensing applications. A significant advance is the elimination of unworkably large look-up tables by using a single simple algorithm for performing the required encoding and decoding operations. The method is conceptualized in a 'transmission cone' context which assists a user in interacting with the system. The user can roam over large images, zoom to various levels of resolution, and cause specified subregions of interest in the image to fill in to full resolution, at a tremendous saving in time.
Solid modeling (Panel Session)
Authors: Machover Carl , Vogel Carl , Witte Donald R. , Bliss Frank W.
Published: November 2005

In the past few years there has been a lot of interest and excitement generated by solid modeling. Numerous papers have been presented on the value and benefits of this technology. Many talented individuals have contributed to the state of the art. Solid modeling has played a larger role at SIGGRAPH in the past three years, with tutorials, panel discussions and technical papers. All this material has been presented for the most part by academics, researchers and developers of solid modeling systems.

The users of solid modeling systems have yet to be heard from. The reason is that there have been very few of them out there in the past. However, that situation is slowly changing. Now that several CAD/CAM vendors are marketing solid modeling systems, a small cadre of users does exist.

This panel will be composed primarily of users of solid modeling systems. They will discuss topics of interest to potential users (and also developers) of solid modelers. Questions to be addressed include:

What is the status of solid modeling systems from a user standpoint?

Can the present solid modelers be used in a production environment today?

Should a solid modeling system replace the present wire frame and surface systems or be integrated with them?

What are the problems associated with using a solid modeling system?

How good is the user interface?

Does the necessary application software exist?

The primary intent of this Panel discussion is to give the potential user some idea as to whether the available solid modeling systems are useful for his applications.

It is beginning to look like the next generation CAD/CAM system for mechanical design will be a solid modeler. The big question is “when will this occur?”
Color table animation
Authors: Shoup Richard G.
Published: November 2005

Even a small amount of animation can greatly enhance graphic communication—particularly when it is desired to show change, movement, or a complex idea or relationship. In raster scan display systems, however, the cost of providing animation has usually been prohibitively high due to the large bandwidths involved in changing a picture rapidly. This paper describes a simple method for providing a limited but very useful real-time interactive animation capability on many existing frame buffer systems. Color table animation relies on changing only the colors of objects and areas present within a single, static picture via the frame buffer's color table RAM. Several variations of this technique are discussed and examples are given of such a capability in use for illustration, educational animation, and television graphics.
Computer graphics for large scale two- and three-dimensional analysis of complex geometries
Authors: Brown Bruce Eric
Published: November 2005

A comprehensive set of programs have been developed for analysis of complex two- and three-dimensional geometries in the Mechanical Engineering Department of the University of California's Lawrence Livermore Laboratory. State of the art finite element and hydrodynamic codes are being used for the analytical portion of the work. To assist the analytical effort, several additional codes which depend heavily on graphics have been developed. These are basically used for the pre- and post-processing of the data. Prior to running any analysis, the geometry of the body of interest must be represented in the form of small “finite elements”. After the analysis is run, the data must be post-processed. Both spatial and temporal data exist in the database. It is the database between the analysis codes and the post-processors which allows a wide variety of analysis codes to use the same post-processors.

The temporal plotting codes produce time histories for specified quantities (i.e. temperature, pressure, velocity, stress, etc.) at various locations within the body. They may also produce cross-plots of these variables (i.e. stress vs strain at a particular position). For plotting of the spatial data two codes are used. The first is for two-dimensional geometries and the second is for three-dimensional models. For three dimensions, the Watkins' hidden surface/line processor is utilized for plots. The spatial plotters will display contour lines on vector output devices and color fringes (or gray values) on raster output devices. They both may also display deformed geometries. Further the three-dimensional code has extensive animation capabilities for movie productions. These graphics codes are used with a wide variety of analyses codes and form a very comprehensive package for the engineering analysis of two- and three-dimensional bodies.
Transparency for computer synthesized images
Authors: Kay Douglas Scott , Greenberg Donald
Published: November 2005

Simple transparency algorithms which assume a linear transparency over an entire surface are the type most often employed to produce computer synthesized images of transparent objects with curved surfaces. Although most of the images created with these algorithms do give the impression of transparency, they usually do not look realistic. One of the most serious problems is that the intensity of the light that is transmitted through the objects is generally not proportional to the amount of material through which it must pass. Another problem is that the image seen behind the objects is not distorted as would naturally occur when the light is refracted as it passes through a material of different density.

Use of a non-linear transparency algorithm can provide a great improvement in the realism of an image at a small additional cost. Making the transparency proportional to the normal to the surface causes it to decrease towards the edges of the surface where the path of the light through the object is longer. The exact simulation of refraction, however, requires that each sight ray be individually traced from the observer, through the picture plane and through each transparent object until an opaque surface is intersected. Since the direction of the ray would change as each material of differing optical density was entered, the hidden surface calculations required would be very time consuming. However, if a few assumptions are made about the geometry of each object and about the conditions under which they are viewed, a much simplier algorithm can be used to approximate the refractive effect. This method proceeds in a back to front order, mapping the current background image onto the next surface, until all surfaces have been considered.
ATOMLLL
Authors: Max Nelson L.
Published: November 2005

The ATOMS program, written at Bell Telephone Laboratory, is capable of determining the visible portions of a scene consisting of interpenetrating spheres and cylinders, put together to represent “space-filling” or “ball-and-stick” molecular models. The Lawrence Livermore Laboratory version contains enhancements to add shading and highlights, and to render the spheres on film as ellipses, so they will appear round when projected in various wide-screen formats.

The visible parts of each sphere or cylinder are shaded by a minicomputer controlling the film recorder, thus releasing the main computer from transferring the millions of intensity values for each frame. The minicomputer is microprogrammed with an efficient algorithm for the intensities, which uses the color look-up tables in the film recorder to store the reflectance as a function of angle of incidence.
Computer drafting of stones, wood, plant and ground materials
Authors: Yessios Chris I.
Published: November 2005

Architectural presentation drawings frequently require the drafting of stones, wood patterns, plants and ground materials, which, contrary to the majority of drafting tasks, cannot rely on repetitious procedures. This paper discusses and illustrates computer implemented algorithms which generate graphic representations of the above materials.

Simulating a process known to be applied in practice is certainly a sound approach, and one such algorithm, applicable for the derivation of stone walls, is presented, But the majority of the algorithms discussed are based on a technique which introduces randomly generated disturbances on initially regular patterns. The latter algorithms in particular have produced highly satisfactory graphic representations, which include frequently hand-made qualities.
Special session on large scale applications of computer charting and mapping in industry (Panel Session)
Authors: Paller Alan , d'Hondt Walter , Dahl David , Dupree Robert L.
Published: November 2005

1. It will demonstrate, with specific examples, the types of planning, justification, expense, and results that are part of the implementation of new computer graphics applications; and,

2. It will attempt to bring out the major barriers to implementation of computer graphics in large organizations and how those barriers may be overcome.

The session is designed to help developers of the new advances in computer graphics software and hardware technology better understand the environments in which their tools will be used in order to optimize the use of the tools they develop. Too often developers of new tools have little opportunity to “get inside the heads” of the managers who will take these new tools and implement them. Through speakers and discussion, the session will draw together the experiences of people who have done the hard work necessary to estimate the costs and benefits and persuade top management that the project is worthwhile, to find the right hardware and software, and to train the staff to work with the new systems.
Interactive color map displays of domestic information
Authors: Dalton J. , Billingsley J. , Quann J. , Bracken P.
Published: November 2005

Governmental decision makers require an increasing variety and volume of information in order to formulate effective policies, plans, and legislation. Moreover, rapid access to this broad body of information is critical to timely and effective governmental action. This paper describes a recent joint project undertaken by the NASA/Goddard Space Flight Center and the Bureau of the Census at the request of the Executive of the President to demonstrate the potential of graphic information display technology for the rapid delivery and effective display of Federal statistics. This project resulted in the development of a prototype Domestic Information Display System which was demonstrated to President Carter, members of Congress, and their respective staffs in June 1978.

The Domestic Information Display System is an interactive, menu-driven software system which produces single and bivariate choropleth maps of socio-economic data by county at the national and state level, and by census tract for Standard Metropolitan Statistical Areas (SMSA's). Selected subareas of national and SMSA maps may be dynamically enlarged to show greater detail. Histogram displays may be selected to show statistical as well as geographic structure.

The system is minicomputer-based and utilizes the image manipulation capabilities of a raster-scan color graphics terminal designed at NASA/Goddard as part of the Atmospheric and Oceanographic Information Processing System (AOIPS) which was adapted to demonstrate the potential of a Domestic Information Display System. The system is highly interactive and can produce a color map display within seconds of the selection of a data item from a menu.

This paper discusses the operation of the Domestic Information Display System, presents sample output products, and describes in detail the software and hardware organization through which the system flexibility and rapid response were achieved.
On the rendering of surfaces
Authors: Forrest A. R.
Published: November 2005

Despite the relative sophistication of modern surface design systems, many graphical renderings of surfaces are rather crude. The paper discusses several possible renderings, including various line drawings methods, realistic and functional shading, and combinations of line drawings and smooth shading. It concludes that a good choice is the superposition of contours or sections on either realistic or Gaussian curvature shading.
Tint fill
Authors: Smith Alvy Ray
Published: November 2005

To fill a connected area of a digital image is to change the color of all and only those pixels in the area. Fill algorithms for areas defined by sharp boundaries (e.g., a white area surrounded by a black curve) have been implemented at several color computer graphics installations. This paper presents an algorithm for the more difficult problem of filling areas with shaded boundaries (e.g., a white area surrounded by a curve consisting of several shades of gray). These images may arise from digitizing photographs or line drawings with a scanning video camera, or they may be generated by programs which produce antialiased line segments or dekink black-and-white images. When an area in such an image is to be filled with a new color, it is desirable to have the fill algorithm understand the shaded edges and maintain the shading with shades of the new color instead of the old. The tint fill algorithm presented here accomplishes this task. Its name arises from its ability to change only the tint (hue and saturation) of a pixel, leaving the value (blackness) unchanged. Although the algorithm was motivated by and is written in terms of color, it has a more general interpretation, which is also presented.
SoftCel - an application of raster scan graphics to conventional cel animation
Authors: Stern Garland
Published: November 2005

The system described uses frame buffers to provide digital analogues to the traditional processes of copying pencil drawings onto cels, painting them, and photographing them. The copying process is replaced by scanning the pencil drawings with a television camera and digitizing the video signal. Several image processing operations are performed on the digitized drawings to condition them for the next step, interactive painting of the drawings mediated by a computer program. The painted drawings are then combined with each other and painted backgrounds for frame by frame recording on film or video tape.
Towards an interactive high visual complexity animation system
Authors: Csuri C. , Hackathorn R. , Parent R. , Carlson W. , Howard M.
Published: November 2005

A computer animation system is discussed which employs interactive techniques and presents a unified approach to the graphical display of complex three dimensional data. The system facilitates the generation, manipulation and display of highly detailed data with the aid of interactive devices and a video interface to a standard color TV monitor. The system enables the animator to create a variety of objects (including texture) and to specify the necessary transformations for animation sequences. A run length processing technique combined with a brute force Z-buffer algorithm has been newly designed and implemented that can handle the intersection of several million faces, lines and points. This makes possible a full range of visual cues to simulate fire, smoke, water and complex 3-D texture such as grass, hair and bark. Basic concepts and approaches are described. The display algorithm and the procedure model to generate texture are presented and the implications of the system for computer animation are discussed. Extensions to the system are outlined which include a unique graphics display processor currently under construction that includes a partial implementation of the display algorithm in hardware.
Parallel processing techniques for hidden surface removal
Authors: Kaplan Michael , Greenberg Donald P.
Published: November 2005

Previous work in the hidden-surface problem has revealed two key concepts. First, the removal of non-visible surfaces is essentially a sorting problem. Second, some form of coherence is essential for the efficient solution of this problem.

In order to provide real-time simulations, it is not only the amount of sorting which must be reduced, but the total time required for computation. One potentially economic strategy to attain this goal is the use of parallel processor systems. This approach implies that the computational time will no longer be dependent on the total amount of sorting, but more on the appropriate division of responsibility.

This paper investigates two existing algorithmic approaches to the hidden-surface problem with a view towards their applicability to implementation on a parallel machine organization. In particular, the statistical results of a parallel processor implementation indicate the difficulties stemming from a loss of coherence and imply potentially important design criteria for a parallel configuration.
Creating polyhedral stellations
Authors: McKeown Kathleen R. , Badler Norman I.
Published: November 2005

A process for creating and displaying stellations of a given polyhedral solid is described. A stellation is one of many star-like polyhedra which can be derived from a single solid by extending its existing faces. A program has been implemented which performs the stellation process on an input object and generates a 3-dimensional image of the stellated object on a computer graphics display screen. Pictures of icosahedron and rhombictriacontahedron stellations generated by the program are included in the paper.
ATLAS
Authors: Tsurutani Tateyuki , Kasahara Yutaka , Naniwada Masaru
Published: November 2005

The design concepts and languages of a geographic information system ATLAS (
A
dministration and
T
otal
L
anduse
A
nalysis
S
upport system) are proposed.

The database structure is designed based on the geographic information structure concepts which contain semantic structure, topological structure and location structure. For a flexible user interface, the system provides two languages) IGL (
I
nteractive
G
eographic
L
anguage) and GDDL (
G
eographic
D
ata
D
efinition
L
anguage), whose functions are designed based on the geographic information structure concepts. IGL is an interactive end user language, which facilitates information retrieval under geographic and/or statistic conditions and thematic map production. GDDL is a language for a system manager who constructs and maintains the database.
PICTUREBALM
Authors: Goates Gary B. , Griss Martin L. , Herron Gary J.
Published: November 2005

PICTUREBALM is a portable, interactive, LISP-based language system for graphics applications programming. PICTUREBALM's design and initial experimental implementation is described from the point of view of both the user and the language system implementor. The approach of extending a LISP-based language by adding graphical operations was chosen because many of the recognized requirements for graphics programming languages are standard features of LISP-like systems. Future work is proposed.
Stochastic modeling in computer graphics
Authors: Fournier Alain , Fussell Don
Published: November 2005

A recurrent problem in generating realistic pictures by computers is to represent natural irregular objects and phenomena without undue time or space overhead. We develop a new and powerful solution to this problem by modeling objects as sample paths of stochastic processes. Of particular interest are those stochastic processes which previously have been found to be useful models of the natural phenomena to be represented. One such model applicable to the representation of terrains, known as “fractional Brownian motion”, has been proposed by B. Mandelbrot.

The value of a new approach to object modeling in Computer Graphics depends largely on the efficiency of the techniques used to implement the model. We introduce here a new, efficient algorithm for rendering realistic surfaces defined using the stochastic process mentioned above. A major advantage of this technique is that it allows us to compute the surface to arbitrary levels of detail without increasing the database. Thus objects with complex appearance can be displayed from a very small database. The character of the surface can be controlled by merely modifying a few parameters. A similar change allows complex motion to be created inexpensively.
A 3-dimensional representation for fast rendering of complex scenes
Authors: Rubin Steven M. , Whitted Turner
Published: November 2005

Hierarchical representations of 3-dimensional objects are both time and space efficient. They typically consist of trees whose branches represent bounding volumes and whose terminal nodes represent primitive object elements (usually polygons). This paper describes a method whereby the object space is represented entirely by a hierarchical data structure consisting of bounding volumes, with no other form of representation. This homogencity allows the visible surface rendering to be performed simply and efficiently.

The bounding volumes selected for this algorithm are parallelepipeds oriented to minimize their size. With this representation, any surface can be rendered since in the limit the bounding volumes make up a point representation of the object. The advantage is that the visibility calculations consist only of a search through the data structure to determine the correspondence between terminal level bounding volumes and the current pixel. For ray tracing algorithms, this means that a simplified operation will produce the point of intersection of each ray with the bounding volumes.

Memory requirements are minimized by expanding or fetching the lower levels of the hierarchy only when required. Because the viewing process has a single operation and primitive type, the software or hardware chosen to implement the search can be highly optimized for very fast execution.
A linear time exact hidden surface algorithm
Authors: Franklin Wm Randolph
Published: November 2005

This paper presents a new hidden surface algorithm. Its output is the set of the visible pieces of edges and faces, and is as accurate as the arithmetic precision of the computer. Thus calculating the hidden surfaces for a higher resolution device takes no more time. If the faces are independently and identically distributed, then the execution time is linear in the number of faces. In particular, the execution time does not increase with the depth complexity.

This algorithm overlays a grid on the screen whose fineness depends on the number and size of the faces. Edges and faces are sorted into grid cells. Only objects in the same cell can intersect or hide each other. Also, if a face completely covers a cell then nothing behind it in the cell is relevant.

Three programs have tested this algorithm. The first verified the variable grid concept on 50,000 intersecting edges. The second verified the linear time, fast speed, and irrelevance of depth complexity for hidden lines on 10,000 spheres. This also tested depth complexities up to 30, and showed that perspective scenes with the farther objects smaller are even faster to calculate. The third verified this for hidden surfaces on 3000 squares.
Application of graphical interaction to the analysis of radio astronomy data
Authors: Torson James M.
Published: November 2005

A highly interactive computer graphics system has been implemented for the display and analysis of high-resolution radio images which are produced by the Very Large Array radio telescope being built by the National Radio Astronomy Observatory. Some of the users of this system are in-house scientists who use the system routinely. However, many of the users are occasional visitors from other institutions who are not necessarily computer programming experts and who have little time or inclination to learn a complex data processing control language. In order to accommodate this mix of users, the system is controlled primarily through the use of a data tablet. Appropriate feedback to the user is provided by both a refreshed line drawing display and a color raster scan image display. Keyboard input is used only for specifying output file names and for specifying a few of the numerical parameters for processing operations. After the digital images are received from another computer system, the entire display and analysis system runs in a stand-alone PDP-11/40. The use of a line drawing display for user interaction and for displaying system status information has proven to be a very useful technique. Although the system is powerful and flexible, the user interface is friendly and can be quickly and easily learned.
Procedure models for generating three-dimensional terrain
Authors: Marshall Robert , Wilson Rodger , Carlson Wayne
Published: November 2005

A method for generating arbitrary terrain models, including trees, bushes, mountains, and buildings, is described. Procedure models are used to combine fundamental data elements in the creation of unified objects comprising the terrain model. As an example, a procedure model to generate arbitrary trees of various species is implementation. These are the generation of the low level data elements, specification of input parameter requirements, and a brief explanation of the algorithmic structure. Terrain images rendered by this process are included, as are diagrams and illustrations explaining the procedure model organization. Comparisons with previous work are made.
Dynamic scan-converted images with a frame buffer display device
Authors: Jackson J. H.
Published: November 2005

A color interactive display system which produces images of three-dimensional polygons and labels on a frame buffer display device is being developed. The entire image is scan converted and written into the frame buffer whenever it is modified. Since an entire image cannot be written into the frame buffer faster than 4.6 frames per second for the particular device chosen, an illusion of continuous motion cannot be supported. However, a rate of 3 frames per second has been found sufficient to provide feedback to continuous user input.

In order to achieve this frame rate for a reasonably complex picture, the display device has been microprogrammed to accept run length encoded data and text, and the instruction set of the computer has been extended by microprogramming special-purpose instructions which perform visible surface calculations. These microprograms currently can process a scene which consists of up to 170 polygons at 3 frames per second.
Adaptation of scan and slit-scan techniques to computer animation
Authors: Parke Frederic I.
Published: November 2005

The adaptation and generalization of scan and slit-scan animation stand techniques for use in computer generated animation is discussed. Scan and slit-scan techniques are based on moving artwork, camera, and, for slit-scan, a thin aperture while the camera shutter is open. These processes can be described as selectively sampling an environment over time and recording the result as a single image. Sequences of such images form the animated film. Rather than use mechanical means to accomplish this, it is possible to develop algorithms which mimic this processes but are based on sampling dynamic environment descriptions to generate computer produced images.

The use of computer graphics allows these techniques to be generalized in ways difficult or impossible even with very elaborate animation stands. Use of multiple independent scanning apertures and three-dimensional environments are natural generalizations.

The exact algorithms used depend on the characteristics of the graphics systems used. An approach based on using a real-time shaded graphics system and an approach using frame buffer systems are outlined. The first approach can also be applied to refresh vector graphics systems.
The integration of subjective and objective data in the animation of human movement
Authors: Calvert T. W. , Chapman J. , Patla A.
Published: November 2005

Animation of human movement can be based either on analog inputs derived directly from actual movements or on symbolic inputs chosen to produce the desired movement. The former type of input can be quite accurate and objective but is a description of the required movement whereas the latter is often quite imprecise and subjective but provides an analysis of the required movements. Two existing systems for a computer based animation are being used to explore the problems involved in integrating such inputs. Specifically, animation driven by analog signals from electro-goniometers is integrated with animation derived from Labanotation commands; the results are illustrated with a short movie.
B-spline surfaces for ship hull design
Authors: Rogers David F. , Satterfield Steven G.
Published: November 2005

The use of true sculptured surface descriptions for design applications has been proposed by numerous authors. The actual implementation and use of interactive sculptured surface description techniques for design and production has been limited. The use of such techniques for ship hull design has been even more limited. The present paper describes a preliminary implementation of such a system for the design of ship hulls and for the production of towing tank models using numerical control techniques. The present implementation is based on a Cartesian product B-spline surface description. Implementation is on an Evans and Sutherland Picture System supported by a PDP-11/45 minicomputer.

The B-spline surface is manipulated by its associated polygonal net. Both surface and net are three-dimensional. Techniques both good and bad for 3-D picking of a polygon point when the net, its associated surface, and the 3-D picking cue independently exist and can be independently manipulated in three space are presented and discussed.

The shape of a B-spline surface of fixed order is controlled by the location of the polygon net points, the number of multiple points at a particular net point, and the knot vector. Frequently multiple points imply multiple knot vectors. Practical techniques for controlling and shaping the surface with and without this assumption are discussed and the results illustrated.

Experience attained by interactively fitting a single fourth order B-spline surface patch to the forebody half of an actual ship hull described by three dimensional digitized points is discussed and the results illustrated.