bluuebunny/crossref_metadata_2025 huggingface dataset:
Specifying symbol instances
Authors: Foley James D.
Published: November 2005

This paper reviews and compares the uses of dimensioning in the instance and dimensioning in the master to specify instances of symbol definitions in general-purpose graphics programming languages. The processing required to each case is described and compared. Dimensioning in the master is easier to implement, can allow faster display of images because of simpler processing, and semantically is a bit less powerful than dimensioning in the instance. When appropriate, both can gracefully coexist in a graphics language, but the great majority of graphics applications only need the semantic power of dimensioning in the master.
Animation on a satellite graphics system
Authors: Sowar Richard M.
Published: November 2005

Although animation processing capability can be extremely valuable in certain graphics programs, its application is generally limited to users of stand alone, single user graphics systems. This paper describes an organization of software which enables a host program to define and control animations for an intelligent satellite graphics system. The discussion centers around the particular system on which it was implemented, but the technique should be general enough to have wide application. The results have significantly enhanced the operating characteristics of programs in the host-satellite environment.
A system for interactive acquisition and administration of geometric data for thematic map production
Authors: Tuerke Klaus
Published: November 2005

Most computer assisted information systems for planning purposes are designed to produce thematic maps as output. Graphic data processing, on the other hand, has not yet reached the degree of perfection already achieved in other fields of EDP, e.g. commercial and statistical applications. The author and his collegues are integrating cartographic data and presentation techniques gradually into an information system.Within the system being described, the geometric data base is considered as a line network. The edges of the network are represented by strings of orthogonal coordinates (Segment definitions). A unique identifier is assigned to each coordinate string, and the areal units are defined by a sequence of edge identifiers (Polygon definitions).In order to obtain error-free files, strict rules have to be observed and a high degree of accuracy has to be achieved.For this purpose, an interactive system - DIGNET - has been developed to fullfill these objectives: (1) guide the operator through the digitizing session, (2) ask for the appropriate input, (3) create the reference tables, (4) react to erroneous input and operation, (5) detect digitizer malfunctions, (6) allow immediate graphic replay of the digitized data.In order to facilitate the manipulation of the boundary network files, a number of utility programs have been added to the DIGNET-System; among them (1) DIGEDI - to prepare maps for digitzing, (2) DIGLIST - to list all results from digitizing sessions, (3) DIGMERGE - to merge two or more submaps into one final map.
The application of the intercolor 8000 terminal to thematic cartography
Authors: Carter James R. , Icove David J.
Published: November 2005

The Intercolor 8000 color video terminal is used in conjunction with a timesharing computer system for applications in thematic cartography. The version of the terminal discussed can resolve the screen into a matrix of 25 rows by 80 columns with colored characters on colored backgrounds. Using the plot mode, the screen can be further resolved into single-color cells of 100 rows by 160 columns. The value and limitations of the terminal are discussed in terms of the selection and brightness of the eight colors, the dimensions of the cells and the ability to mix colors in small cells. The possibilities of using the terminal for dot, choropleth and isarithmic maps are explored. Acetate overlays can be used to add base lines such as boundaries and rivers and the composite images can be recorded on standard slide film.
Enhanced graphics performance with user controlled segment files
Authors: Little W. D. , Williams R.
Published: November 2005

This paper describes a simple idea for extending the use of display segment files in computer display systems. The extension is to provide manual control of segment files in a display terminal as well as program control from a host computer. The use of display segments local to the display makes it possible to speed up the rate at which pictures are displayed when the communications line to the host computer is slow or when the host machine is time-shared and heavily loaded. The manual control of segments are terminal functions that work for any program including old programs that knew nothing about display segments.
Graphic and relational data base support for problem solving
Authors: Weller Dan , Williams Robin
Published: November 2005

This paper describes a general purpose 'picture building system'. The main purpose of the system is to provide an environment wherein an application programmer can interactively create and modify applications. In addition to a graphics software package the picture building system provides high-level application building tools and a relational data base as integral parts of the system. An interpreter is provided to draw pictures from data stored in relations. A correlation handler is provided to allow a user to identify and manipulate displayed items. A relations editor is provided to interactively create, edit, and display relations. The picture building system works on a variety of graphic and nongraphic terminals.
Remote programmability of graphic interactions in a host/satellite configuration
Authors: Moulton Samuel D. , Corman Philip J.
Published: November 2005

This paper describes the remote programmability of graphic-oriented interactions in a large, time-shared host/multiple-satellite configuration. The philosophy and architecture of a pseudo machine -- the Programmable Graphics Processor (PGP) -- is presented along with a description of the higher-level language used in the host to specify programs for execution in the satellite. These programs are first compiled into PGP machine language in the host and then transmitted to the satellite where they are executed in response to asynchronous interrupts (attentions) originating from various types of interactive graphic input devices. In this manner, fairly complex and tailored interactions such as multiple line rubberbanding and limited area tracking are specified conveniently by applications programs in the host computer.
"SGP"
Authors: Putnam Richard E. , Carmichael Ralph L.
Published: November 2005

This paper presents a simple scheme for manipulating graphical information. The basic idea is to generate a user-readable, and therefore editable, file of device-independent picture descriptions. This file would typically be created by a set of FORTRAN-callable subroutines, each having a specific function (draw a vector, draw an axis, write text), but could be created in more direct ways by a user sufficiently familiar with the file structure. Once such a file has been created and perhaps examined and edited, a postprocessor may be selected to translate the file into the device-dependent instructions necessary to produce a picture on a specific device. If the file is saved, a different postprocessor could obviously be used later to generate the same picture on another device.
The design of a low cost video graphics terminal
Authors: Baskett Forest , Shustek Leonard
Published: November 2005

We have designed and built a computer terminal that provides low cost, high quality graphics and programmable text processing by taking advantage of the latest memory and microprocessor technology. A microprocessor control element allows most of the control functions to be programmed so that all of the control electronics require less than 100 integrated circuits. The graphic image is generated by a microprocessor which accepts vector commands intended for a Tektronix storage tube display terminal. The microprocessor maps those vector commands into a random access memory, and the resulting bit map of the graphic image is displayed on a standard TV monitor. Reasonable resolution in the graphic image requires a large number of bits in the bit map, but with the use of 4K memory chips, less than 100 integrated circuits are required for the bit map memory in our design. At 1975 small-quantity prices, the parts cost for the terminal is approximately $2000.
Computer rendering of lobster neurons
Authors: Max Nelson L.
Published: November 2005

At Carnegie Mellon University, the PDP-10 and PDP-11 computers have been used to trace thin sections of stained neurons in a lobster swimmeret ganglion, and to reconstruct the global structure of the neuron from the sections. This paper will present two sorts of graphic pictures of the final reconstructed neuron; vector drawings with hidden lines, and shaded raster drawings of the neuron inside a transparent shell representing the outer surface of the ganglion. The hidden line program handles curving cylindrical tubes of varying radii, and shows only the visible contours. The raster program is a modification of Sproul's version of the Watkins Algorithm, and applies Phong shading to both opaque and semi-transparent surfaces. The shaded output is rendered on the Carnegie-Mellon video system.
Quantitative imaging of dynamic structure and function of the heart, lungs and circulation by computerized reconstruction and subtraction techniques
Authors: Robb Richard A. , Ritman Erik L. , Greenleaf James F. , Sturm Ralph E. , Herman Gabor T. , Chevalier Peter A. , Liu Hsun K. , Wood Earl H.
Published: November 2005

Conventional radiographic imaging techniques are not adequate for determination of the true, dynamic changes in shape and dimensions of the intact working heart, lungs and circulation which are required for accurate quantitative determination of the structure and function of these organ systems. This paper describes a computerized method for obtaining images of the dynamic spatial distribution of x-ray attenuation throughout multiple parallel cross-sectional planes bisecting the intact thorax, with 1-mm spatial resolution and 60-per-second temporal resolution, and for generating time delay video and cine displays of the spatial and temporal sequences of these cross-sectional images. Operator-interactive computer programs facilitate the dynamic display of reconstructed cross sections of the heart and lungs, with or without dynamic background subtraction, and permit calculation and display of any desired single or spatially related set of coronal, sagittal or obliquely oriented sections. Such displays permit viewing of the temporal and spatial distribution of contraction, expansion, and perfusion of these organs over their full anatomic extent in various orientations and in variable time-base modes ranging from stop-action to real-time. The results achieved with this computerized system for three-dimensional reconstruction and display of moving organs, particularly the heart, lungs, and circulation, demonstrate the potential for providing greatly improved techniques for investigation of the relationships of the dynamic three-dimensional anatomy and blood-tissue exchange properties of moving organ systems to their regional and integrated function, and ultimately for providing powerful new clinical diagnostic methods for elucidation of abnormalities of the heart, lungs and circulation in man.
A parametric algorithm for drawing pictures of solid objects bounded by quadric surfaces
Authors: Levin Joshua Z.
Published: November 2005

An algorithm for drawing pictures of three-dimensional objects, with surfaces made up of patches of quadric surfaces, is described.The emphasis of this algorithm is calculating the intersections of quadric surfaces. A parameterization scheme is used. Each quadric surface intersection curve (QSIC) is represented as a set of coefficients and parameter limits. Each value of the parameter represents at most two points, and these may easily be distinguished. This scheme can find the co-ordinates of points of even quartic (fourth-order) intersection curves, using equations of no more than second order.Methods of parameterization for each type of QSIC are discussed, as well as surface bounding and hidden surface removal.
Making graphics work
Authors: Lavick Jerry J.
Published: November 2005

This paper describes some of the operational considerations of a large data processing installation involved in support of an interactive computer system in heavy production use. Application and operating system software has varied over the continued growth and expansion of this system. Mechanisms for user input and feedback, vital aspects to its successful operation, are discussed. The application specifically cited is MCDONNELL DOUGLAS' CAD/CAM (Computer-Aided-Design/Computer-Aided-Manufacturing) System and highlighted are daily operations of its computer graphics terminals. This system is configured to provide 95% availability with backup switchability features. Typical response, varying with the nature of the user application, ranges from 0.1 to 60 seconds.
Computer-aided coarse grid layout technique for photomasks
Authors: Geer Ronald G.
Published: November 2005

A comprehensive computer-aided mask layout technique has been developed which permits quick conversion of LSI circuits into working photomasks. It is an efficient solution to the problem when the demand for customized circuit layouts greatly overshadows the more standardized techniques. No computer background or programming experience is required. This approach allows the designer to quickly compose high-density mask layouts using simple free-hand line symbols. These easily drawn symbols, representing complex circuitry, utilize a standard device-level building block library which simplifies the conversion of LSI circuits into photomasks, and permits the designer to generate up to 100% of the layout without leaving his desk.
Clamping
Authors: Norton Alan , Rockwood Alyn P. , Skolmoski Philip T.
Published: November 2005

An object space method is given for interpolating between sampled and locally averaged signals, resulting in an antialiasing filter which provides a continuous transition from a sampled signal to its selectively dampened local averages. This method is applied to the three standard Euclidean dimensions and time, resulting in spatial and frame to frame coherence. The theory allows filtering of a variety of functions, including continuous and discrete representations of planar texture.
Light reflection functions for simulation of clouds and dusty surfaces
Authors: Blinn James F.
Published: November 2005

The study of the physical process of light interacting with matter is an important part of computer image synthesis since it forms the basis for calculations of intensities in the picture. The simpler models used in the past are being augmented by more complex models gleaned from the physics literature. This paper is another step in the direction of assimilating such knowledge. It concerns the statistical simulation of light passing through and being reflected by clouds of similar small particles. (It does not, however, address the cloud structure modeling problem). By extension it can be applied to surfaces completely covered by dust and is therefore a physical basis for various theories of diffuse reflection.
The detailed semantics of graphics input devices
Authors: Rosenthal David S. H. , Michener James C. , Pfaff Günther , Kessener Rens , Sabin Malcolm
Published: November 2005

The concept of
virtual input devices,
enunciated by Wallace, has been the accepted basis for producing device-independent interactive graphics systems. It was used by GSPC for the Core System, and it underlies the draft international standard GKS.

During the recently concluded technical review of GKS, the input facilities became a bone of contention. The discussions revealed many inadequacies in the virtual input device concept, and were finally resolved using a refined and extended model of input, which is presented here by some of the participants in the discussions. Examples are included, showing how the GKS facilities derive from the model, and the Core's “STROKE” device is used to show how the model controls future extensions to GKS. The model is also used to describe the other differences between the input facilities of the Core System and GKS.
Generation and display of geometric fractals in 3-D
Authors: Norton Alan
Published: November 2005

We present some straightforward algorithms for the generation and display in 3-D of fractal shapes. These techniques are very general and particularly adapted to shapes which are much more costly to generate than to display, such as those fractal surfaces defined by iteration of algebraic transformations. In order to deal with the large space and time requirements of calculating these shapes, we introduce a boundary-tracking algorithm particularly adapted for array-processor implementation. The resulting surfaces are then shaded and displayed using z-buffer type algorithms. A new class of displayable geometric objects, with great diversity of form and texture, is introduced by these techniques.
A new general triangulation method for planar contours
Authors: Ganapathy S. , Dennehy T. G.
Published: November 2005

The problem of approximating the surface spanning a given set of 3D points as a polyhedron of triangular faces (“triangulation”) is a significant one, and has many applications in the fields of computer graphics and computer vision. In this paper, several solutions to this problem are reviewed. These solutions can be grouped into two classes, and particular emphasis is given to the class of surfaces spanned by parallel planar contours. For a contour pair

P
0
,P
1
,...P
m−1

and

Q
0
,Q
1
,...Q
n−1

, a graph theoretic approach can be used to arrive at a class of solutions, each requiring exactly
m+n
steps to triangulate the pair. Existing methods (both rigorous and heuristic) for extracting a particular solution from this group are reviewed, and a new heuristic based on inter-contour coherence is proposed. This heuristic is being used in the field of Ultrasonic Non-destructive Evaluation to produce images of flaws in pressure vessels, and its performance is shown to compare favorably with methods of greater computational complexity. It is believed that this heuristic can also be used with success in industrial vision systems where similar contours are obtained using a laser range finder.
FLAIR - user interface dialog design tool
Authors: Wong Peter C. S. , Reid Eric R.
Published: November 2005

To aid the system designers in achieving early involvement of the users, FLAIR (a user interface dialog design tool) was conceptualized and developed. FLAIR allows the designer to rapidly prototype a system's Man-Machine Interface.

A system designer can select a desired mix of input/output devices ranging from voice to high resolution graphics equipment. FLAIR prompts its users with a dynamic menu according to a pre-defined English-like syntax. Commands are entered by the designer's own voice. Entered commands are validated by voice pattern recognition and command language-gating. Pointing devices are used to locate, place, and/or pick objects from the RAMTEK 9400 25” high-resolution color monitor.

The graphics display portion of FLAIR is handled by a Core Standard graphics package. This particular package also fits the specific needs of FLAIR in that it makes available most of the RAMTEK 9400's hardware features.

A relational DBMS has been integrated into FLAIR in order to manage system and user-defined data relationships. The user-defined data can be associated with a particular on-screen graphics symbol, and can then be queried at a later time.

In addition to single graphics snapshots (or “static frames”), FLAIR allows the system designer to create command menu hierarchies for “dynamic scenarios.” This allows the designer to simulate, through client menu item selection, the system control flow. He can, in effect, create a tree of menus, traverse the tree at will, and select more menus or system actions as desired. All menus appear as sensitized areas on the graphics screen, and can be selected via any of the available input devices.

It is estimated that a system designer can greatly improve his dialog design productivity by using FLAIR. The designers need not code any formal programs. The designer need not master the usage of the host computer, the graphic input/output systems, the menu controls, or the database programming before his designs are realized. FLAIR is there to assimilate, assemble, save and exercise his instructed operator dialog.
A user interface management system
Authors: Kasik David J.
Published: November 2005

The design and construction of the user interface to interactive systems is receiving increased attention. This paper describes a user interface management system that allows a designer/developer to focus on the logical functionality of an application without the usual bookkeeping associated with a conventional programming language. The user interface management system contains two components: a special purpose, application independent dialogue specification language and a run-time interpreter that provides a number of interaction extensions not possible with procedure libraries.
The device model of interaction
Authors: Anson Ed
Published: November 2005

Any interactive system can be described in terms of the devices it involves, and their interconnections. Similarly, each device can be described in terms of simpler devices and their interconnections. Such descriptions are strictly modular, and well structured.

This observation allows any system to be described, at all levels, by the same language. Such descriptions have intuitive appeal for hardware as well as software components, and for process control applications as well as human-machine interaction. The Device model of interaction, as described here, can ease the job of designing user- friendly interactive systems, and can be adapted for automatic compilation.

As an example, the design of an actual system component is discussed. The design is presented, at several levels, in a Pascal-like notation. It represents a module created to provide a human-machine interface via a graphic tablet, keyboard and video monitor.
Star graphics
Authors: Lipkie Daniel E. , Evans Steven R. , Newlin John K. , Weissman Robert L.
Published: November 2005

The XEROX Star 8010 Information System features an integrated text and graphics editor. The Star hardware consists of a processor, a large bit-mapped display, a keyboard and a pointing device. Star's basic graphic elements are points, lines, rectangles, triangles, graphics frames, text frames and bar charts. The internal representation is in terms of idealized objects that are displayed or printed at resolutions determined by the output device. This paper describes the design and implementation of a graphics editor using an object-oriented technique based on a Star-wide subclassing method called the Trait Mechanism.
A rectangular area filling display system architecture
Authors: Whelan Daniel S.
Published: November 2005

A display system architecture which has
rectangular area filling
as its primitive operation is presented. It is shown that lines can be drawn significantly faster with this architecture than with a pixel display system. The rendition of filled boxes is also faster showing an

O(n
2
)

speed improvement. Furthermore filled polygons can be rendered with an
O(n)
speed improvement.

The design and implementation of this rectangular area filling architecture are discussed and refined. A custom VLSI integrated circuit is currently being designed to implement this rectangular area filling architecture and at the same time reduce the display memory system video refresh bandwidth requirements.
Approaches to solid modelling (Panel Session)
Authors: Bliss Frank , Carmody William , Johnson Robert , Schloessel Martin , Swarbrick John , Malin Leon
Published: November 2005

Solid modelling systems in current use are based on approaches that are fundamentally different. The panelists will discuss the advantages and disadvantages of the different approaches, especially from the user's point of view.
Graphical tools for interactive image interpretation
Authors: Mckeown David M. , Denlinger Jerry L.
Published: November 2005

This paper describes BROWSE, an interactive raster image display facility which is a major component of a larger integrated Map Assisted Photo-interpretation System (MAPS), being developed as a prototype interactive aid for photo-interpretation. Application areas for this research include image cartography, land use studies and reconnaissance, as well as image database organization, storage, and retrieval.

BROWSE is a window-oriented display manager which supports raster image display, overlay of graphical data such as map descriptions and image processing segmentations, and the specification and generation of 3D shaded surface models. Digitized imagery from black and white and color aerial mapping photographs is displayed by BROWSE at multiple levels of resolution and allows for dynamic positioning, zooming, expansion or shrinking of the image window. Map data represented as vectors and polygons can be superimposed on the imagery through image-to-map registration. Access to collateral map databases and terrain models may be accomplished using the BROWSE graphical interface. Finally, the window representation gives a convenient communication mechanism for passing image fragments to image interpretation programs, which generally run as separate processes. The results of such processing can be returned to BROWSE for further processing by the user.

We will discuss the rationale behind the design of BROWSE as well as its application to domains including aerial photo-interpretation and 3D cartography.
A morphological study of the form of nature
Authors: Kawaguchi Yoichiro
Published: November 2005

A process of recreating some forms of nature, including shells, horns, tusks, claws, and spiral plants, is herein described. The forms of nature based on spirals and ramification are generated not through the use of object data calculated by measurement, but through the use of an algorithmic structure based on the laws of nature. Although there are a myriad of forms to the shapes of nature, they are represented on the basis of one common principle, which can be expressed by means of the same mathematical expressions. The graphic software which is called “GROWTH” (Growth Rationale Object Work THeorem) has now been designed to create these forms automatically. GROWTH incorporates the rational, common principle of geometrical series which are found in the structute of biological objects.
An interactive graphics environment for architectural energy simulation
Authors: Pittman Jon H. , Greenberg Donald P.
Published: November 2005

An interactive computer graphics system has been developed for the architecture profession which provides a “design environment” for the evaluation of building energy consumption. The system includes an integrated set of graphic input tools which generate the geometric and attribute data necessary for the determination of thermal load in buildings. In addition, a comprehensive set of graphical output routines has been created to allow the designer to visually interpret the results of alternative design strategies.
Ray tracing parametric patches
Authors: Kajiya James T.
Published: November 2005

This paper describes an algorithm that uses ray tracing techniques to display bivariate polynomial surface patches. A new intersection algorithm is developed which uses ideas from algebraic geometry to obtain a numerical procedure for finding the intersection of a ray and a patch without subdivision. The algorithm may use complex coordinates for the (
u, v
)-parameters of the patches. The choice of these coordinates makes the computations more uniform, so that there are fewer special cases to be considered. In particular, the appearance and disappearance of silhouette edges can be handled quite naturally. The uniformity of these techniques may be suitable for implementation on either a general purpose pipelined machine, or on special purpose hardware.
An algorithm and data structure for 3D object synthesis using surface patch intersections
Authors: Carlson Wayne E.
Published: November 2005

There are several successful systems that provide algorithms that allow for the intersection of polygonal objects or other primitive shapes to create more complex objects. Our intent is to provide similar algorithms for intersecting surface patches. There have been contributions to this concept at the display algorithm level, that is, computing the intersection at the time the frame is generated. In an animation environment, however, it becomes important to incorporate the intersection in the data generation routines, in order that those parts of the intersected object that never contribute to an image are not processed by the display algorithm. This only increases the complexity of the object unnecessarily, and subsequently puts an additional burden on the display algorithms.

An algorithm is described which uses a modified Catmull recursive subdivision scheme to find the space curve which is the intersection of two bicubic patches. An associated data structure is discussed which incorporates this curve of intersection in the patch description in a way suitable for efficient display of the intersected object. Sample output of these intersections are shown which serve to illustrate the capabilities and limitations of the described procedures.
The message is the medium
Authors: Beach Richard J. , Beatty John C. , Booth Kellogg S. , Plebon Darlene A. , Fiume Eugene L.
Published: November 2005

An innovative design for an interactive paint program has been developed based on multiple processes and message passing. Traditional paint programs combine interrupt-driven support of a graphical input device, such as a mouse or tablet, with the coloring of pixels in a raster display. We advocate a different design methodology which is illustrated in our implementation. The multiple processes and message passing primitives provided by some real-time operating systems encourage the design of parallel-program architectures and anthropomorphic programming structures, analogous to artist procedures and the metaphors of Smalltalk.

The Thoth operating system was used to experiment with such an anthropomorphic design. Thoth provides a hospitable environment in which to investigate the distribution of algorithms between software and microprogrammed hardware processes, the performance and responsiveness of a multiple-process interactive program, and experimental user interfaces using an Ikonas 3000 frame buffer.

The paint program consists of processes which handle the graphics tablet, track an iconic cursor, paint a selection of brushes, fill regions of the image, draw lines, and implement the user interface. Some processes have been implemented both in software and microcode.
A language for bitmap manipulation
Authors: Guibas Leo J. , Stolfi Jorge
Published: November 2005

In this paper we propose that bitmaps, or raster images, should be given full citizen status in the world of computer science. We introduce a calculus of bitmap operations and MUMBLE, a programming language appropriate for describing bitmap computations. We illustrate the use of MUMBLE by several interesting graphical applications. We also discuss the structure of BOP, an efficient implementation of the bitmap calculus that is the underpinning of our system.
A conceptual model of raster graphics systems
Authors: Acquah James , Foley James , Sibert John , Wenner Patricia
Published: November 2005

In this paper we present a conceptual model of raster graphics systems which integrates, at a suitable level of abstraction, the major features found in both contemporary and anticipated graphics systems. These features are the refresh buffer; the image creation (scan-conversion) system; the single address-space architecture which integrates the address space of the refresh buffer with those of the image creation system and the associated general-purpose computer; the RasterOp or BitBlt instructions found in some single address-space architectures; the video look-up table, and refresh buffer to screen transformations. Also included are the major components from the conceptual model of vector graphics systems which are embodied in the ACM/SIGGGRAPH/GSPC Core System. Using the conceptual model as a base, we proceed to sketch out the capabilities we have defined in a substantial addition to the Core System. The capabilities are currently being implemented as part of the George Washington University Core System.
Frame-to-frame coherence and the hidden surface computation
Authors: Hubschman Harold , Zucker Steven W.
Published: November 2005

Frame-to-frame coherence is the highly structured relationship that exists between successive frames of certain animation sequences. From the point of view of the hidden surface computation, this implies that parts of the scene will become visible or invisible in a predictable fashion. In this paper the frame-to-frame coherence constraints are identified and characterized for static scenes restricted to stationary, closed, convex, nonintersecting polyhedra. The animation derives from a continuous movement of the viewer. The mathematical analysis of the constraints is geometric, and leads to a characterization of the self-occlusion relationship over a single polyhedron; and to a characterization of the occlusion or change of occlusion relationship over two polyhedra. Based on these constraints, an algorithm is presented which generates successive frames in an animation sequence.
A frame buffer system with enhanced functionality
Authors: Crow F. C. , Howard M. W.
Published: November 2005

A video-resolution frame buffer system with 32 bits per pixel is described. The system includes, in addition to standard features for limited zoom and pan, an arithmetic unit at the update port which allows local computation of many frequently-used pixel-level functions combining stored pixel values with incoming pixel values. In addition to the standard arithmetic and logical functions there are functions for sum to maximum pixel value and difference to minimum pixel value. Comparisons between incoming and stored data are used to implement conditional writes based on depth values for depth-buffer algorithms. Update and refresh ports are designed for a wide range of flexibility allowing simultaneous use by separate tasks and various functional rearrangements of the 32-bit pixel words. The memory architecture, refresh and update ports are described. Examples of widely divergent modes of operation are provided.
Video Panel Session on Interactive Systems
Authors: Baecker Ronald
Published: November 2005

SIGGRAPH has long provided a forum for the presentation, discussion, evaluation, and appreciation of beautiful algorithms and beautiful pictures. The Video Panel Session on Interactive Systems is a new SIGGRAPH event, affording us the opportunity to look at beautiful systems.

The design of interactive systems and of their user interfaces is an art. We possess no systematic design methodology, no effective and universal method of evaluation. We speak in earnest praise of the importance of power, generality, flexibility, ease of use, ease of learning, robustness, and a dozen other universally admired attributes, but we do not know how to construct systems so that they are guaranteed to have these attributes.
The George Washington University Core System implementation
Authors: Foley James D. , Wenner Patricia A.
Published: November 2005

A full implementation of the proposed standard Core System graphics subroutine package, including raster extensions, is described. Emphasis is placed on the internal structure of the implementation, and on critical design decisions. Salient features of the implementation include separate 2D and 3D viewing pipelines, a centralized dispatcher to control the flow of information between various parts of the Core, a strong separation between the device-independent and device-dependent parts of the Core, and either device-independent or device-dependent simulation of missing hardware capabilities.
GRAMPS - A graphics language interpreter for real-time, interactive, three-dimensional picture editing and animation
Authors: O'Donnell T. J. , Olson Arthur J.
Published: November 2005

GRAMPS, a graphics language interpreter has been developed in FORTRAN 77 to be used in conjunction with an interactive vector display list processor (Evans and Sutherland Multi-Picture-System). Several of the features of the language make it very useful and convenient for real-time scene construction, manipulation and animation. The GRAMPS language syntax allows natural interaction with scene elements as well as easy, interactive assignment of graphics input devices. GRAMPS facilitates the creation, manipulation and copying of complex nested picture structures. The language has a powerful macro feature that enables new graphics commands to be developed and incorporated interactively.

Animation may be acheived in GRAMPS by two different, yet mutually compatible means. Picture structures may contain “framed” data, which consist of a sequence of fixed objects. These structures may be displayed sequentially to give a traditional frame animation effect. In addition, transformation information on picture structures may be saved at any time in the form of new macro commands that will transform these structures from one saved state to another in a specified number of steps, yielding an interpolated transformation animation effect.

An overview of the GRAMPS command structure is given and several examples of application of the language to molecular modeling and animation are presented.
An attribute binding model
Authors: Garrett Michael T.
Published: November 2005

An attribute binding model is presented and discussed to illustrate the use of such reference models in the ANSI X3H3 graphics software standardization effort. The model helps in defining and illustrating issues, and in explaining the proposed standard to those who will accept and use it. Using the model components and attributes can be categorized and characterized.
A computer aid for man machine modelling
Authors: Kingsley E. C. , Schofield N. A. , Case K.
Published: November 2005

Computer aids for design ignore, in general, one of the critical areas in present day society. This is the workplace, where men and machines interact to produce goods or generate services with a mixture of social, economic and industrial objectives.

This paper describes the SAMMIE (System for Aiding Man Machine Interaction Evaluation) Computer Aided Design System, which provides the designer with a wide range of aids including ones specifically for the evaluation of ergonomic criteria. A three-dimensional workplace model may be displayed on the screen of a graphics terminal linked to a minicomputer. To this workplace model, a Man Model of variable anthropometry can be added, enabling the workplace to be evaluated against criteria such as those relating to the operator's reach, vision, and fit capabilities.

The system has been used in a wide range of applications including vehicles and aircraft, materials handling equipment, large assembly jigs, commercial and industrial interiors. Examples from some of these are shown illustrating the facilities of the system.
Variational geometry in computer-aided design
Authors: Lin V. C. , Gossard D. C. , Light R. A.
Published: November 2005

A system has been developed which utilizes variational geometry in the design and modification of mechanical parts. Three-dimensional constraints between characteristic points are used to define an object's geometry. Modification of geometry is accomplished by alteration of one or more constraints. A matrix method is used to determine the shape of the part by simultaneous solution of constraint equations. A method for increasing the speed and efficiency of the solution procedure is described. The method uses the relationships between the geometry and constraints to minimize the number of equations and variables to be solved.
DATAPLOT—an interactive high-level language for graphics, non-linear fitting, data analysis, and mathematics
Authors: Filliben James J.
Published: November 2005

This paper describes the design philosphy and features of DATAPLOT—a high-level (free-format English-like syntax) language for:

1) graphics (continuous or discrete);

2) fitting (linear or non-linear);

3) general data analysis;

4) mathematics.

DATAPLOT was developed originally in 1977 in response to data analysis problems encountered at the National Bureau of Standards. It has subsequently been the most heavily-used interactive graphics and non-linear fitting language at NBS. It is a valuable tool not only for “raw” graphics, but also for manuscript preparation, modeling, data analysis, data summarization, and mathematical analysis. DATAPLOT may be run either in batch mode or interactively, although it was primarily designed for (and is most effectively used in) an interactive environmnet. DATAPLOT graphics may appear on many different types of output devices. Due to its modular design and underlying ANSI FORTRAN (PFORT) code, DATAPLOT is portable to a wide variety of computers.

The paper is divided into three general parts: part 1 deals with background motivation and design philosophy; part 2 deals with capability and implementation features; part 3 deals with a comparison of DATAPLOT to other systems/languages.
Creating repeating hyperbolic patterns
Authors: Dunham Douglas , Lindgren John , Witte David
Published: November 2005

A process for creating repeating patterns of the hyperbolic plane is described. Unlike the Euclidean plane, the hyperbolic plane has infinitely many different kinds of repeating patterns. The Poincare circle model of hyperbolic geometry has been used by the artist M. C. Escher to display interlocking, repeating, hyperbolic patterns. A program has been designed which will do this automatically. The user enters a motif, or basic subpattern, which could theoretically be replicated to fill the hyperbolic plane. In practice, the replication process can be iterated sufficiently often to appear to fill the circle model. There is an interactive “boundary procedure” which allows the user to design a motif Which will be replicated into a completely interlocking pattern. Duplication of two of Escher's patterns and some entirely new patterns are included in the paper.
Animating facial expressions
Authors: Platt Stephen M. , Badler Norman I.
Published: November 2005

Recognition and simulation of actions performable on rigidly-jointed actors such as human bodies have been the subject of our research for some time. One part of an ongoing effort towards a total human movement simulator is to develop a system to perform the actions of American Sign Language (ASL). However, one of the “channels” of ASL communication, the face, presents problems which are not well handled by a rigid model.

An integrated system for an internal representation and simulation of the face is presented, along with a proposed image analysis model. Results from an implementation of the internal model and simulation modules are presented, as well as comments on the future of computer controlled recognition of facial actions.

We conclude with a discussion on extensions of the system, covering relations between flexible masses and rigid (jointed) ones. Applications of this theory into constrained actions, such as across rigid nonmoving sheets of bone (forehead, eyes) are also discussed.
Inbetweening for computer animation utilizing moving point constraints
Authors: Reeves William T.
Published: November 2005

This paper presents an approach to computerized inbetweening which allows the animator more control over an interpolation sequence than existing keyframe techniques. In our approach, the animator specifies in addition to a set of keyframe constraints, a set of new constraints called
moving points
. Moving points are curves in space and time which constrain both the trajectory and dynamics of certain points on the keyframes. The sets of keyframes and moving points form a constraint or
patch network
specification of the desired dynamics. Several algorithms are presented for inbetweening or completing such a patch network. By measuring these algorithms with respect to a set of evaluation criteria, the algorithm which best meets our interpolation needs is selected.
Vectorized procedural models for natural terrain
Authors: Max Nelson L.
Published: November 2005

A ray-tracing procedural model is described, in which ocean waves and islands are rendered by different but related algorithms. The algorithms are based on analytic formulas involving arithmetic operations, trigonometric functions, and square roots, and are organized for a vectorizing compiler on a Cray 1, a “supercomputer” with a vector pipeline architecture. Height field methods are used, one vertical scan line at a time, to trace the direct rays to the ocean, where they are reflected. Approximate methods are then applied to find whether the reflected rays meet any other object on their way to the sky. The output, at eight bits per pixel, gives information for shading, e.g. the angle of the surface normal for rays meeting the islands, or the angle of elevation from the horizon for rays continuing unobstructed to the sky.

The output is recorded on a magnetic tape for each frame in one cycle of the wave motion, and plotted offline on a Dicomed D-48 color film recorder. The eight bits per pixel are interpreted by a color translation table, which is gradually changed as the wave cycle is repeated to simulate the changing illumination during sunset.
Cone-spheres
Authors: Max Nelson
Published: November 2005

A cone-sphere consists of two spheres, together with the part of the cylinder or cone tangent to the two spheres and lying between them. Cone-spheres can be rapidly rendered with shading, highlights, texture, or bump maps, and composited to create twisted or branched tubular structures.
Rendering CSG models with a ZZ-buffer
Authors: Salesin David , Stolfi Jorge
Published: November 2005

The ZZ-buffer is a simple acceleration scheme for ray tracing that can be applied to a wide variety of scenes, including those with small features, textured and transparent surfaces, shadows and penumbrae, and depth-of-field effects. In this paper, we describe how the ZZ-buffer algorithm can be adapted to the rendering of scenes defined by constructive solid geometry operations.
Parallel object-space hidden surface removal
Authors: Randolph Franklin Wm. , Kankanhalli Mohan S.
Published: November 2005

A parallel object-space hidden surface removal algorithm for polyhedral scenes is presented. The uniform grid technique is used to achieve parallelism for the hidden line removal. A conflict-detection and back-off strategy is then used to obtain parallelism for the visible region reconstruction from the visible segments. The algorithm has been implemented on a Sequent Balance 21000 shared-memory parallel computer. An average speedup of 10 has been obtained using 15 processors.
Using tolerances to guarantee valid polyhedral modeling results
Authors: Segal Mark
Published: November 2005

A polyhedral solid modeler that operates on boundary representations of objects must infer topological information from numerical data. Unavoidable errors (due to limited precision) affect these calculations so that their use may produce ambiguous or contradictory results. These effects cause existing polyhedral modelers to fail when presented with objects that nearly align or barely intersect[10][7].An object description associating a tolerance with each of its topological features (vertices, edges, and faces) is introduced. The use of tolerances leads to a definition of topological consistency that is readily applied to boundary representations. The implications of using tolerances to aid in making consistent topological determinations from imprecise geometric data are explored and applied to the calculations of a polyhedral solid modeler. The resulting modeler produces a consistent polyhedral boundary when given consistent boundaries as input.