bluuebunny/crossref_metadata_2025 huggingface dataset:
A generalized graphic preprocessor for two-dimensional finite element analysis
Authors: Haber Robert , Shephard Mark , Abel John , Gallagher Richard , Greenberg Donald
Published: November 2005

Input preprocessors have come to be recognized as important components of modern finite element programs. A method is described which utilizes interactive computer graphics digitizing techniques to create a powerful input preprocessor for finite element analysis. A limited number of general mesh generators based on linear blending functions permit the program to handle virturally all two-dimensional topologies. The processes of geometric input and specification of problem-specific “attributes” have been kept separate so that the mesh generation routines may be used with a variety of analysis programs. Graphical editors have been implemented to specify attributes for structural mechanics problems. Although this type of graphical preprocessor shows considerable promise for applications in three dimensions, there are still unresolved problems in the areas of geometrical description, perception, and interactive hardware.
The problems of computer-assisted animation
Authors: Catmull Edwin
Published: November 2005

In the last few years several systems have been written for aiding in the conventional two-dimensional animation process. The main purpose of these systems has been to let the computer produce missing drawings based on extreme drawings produced by animators. While there has been some success and a great deal of optimism, the promise of higher output and quality using a computer has not been realized. The transition from simple drawings optimized for use on the computer to the complicated and detailed drawings of quality conventional animation has been much harder than expected. The principle difficulty is that the animators drawings are really two dimensional projections of three dimensional characters as visualized in the animators head, hence information is lost, ie. one leg obscures another. The problem of making a program infer the original object from its projections is akin to extremely difficult artificial intelligence problems. Efforts to overcome this by drawing skeletons or increasing the number of overlays require more manual intervention thereby offsetting the gains of using the computer. One way to analyze an approach is to determine the average time required of an artist or operator at all stages of animation for every frame. A second problem not generally recognized is that a production animation system requires the management of hundreds of thousands of drawings, hence data base management techniques not normally found in experimental animation systems.
NUDES 2
Authors: Herbison-Evans Don
Published: November 2005

A system is described for producing 16 mm animated films of moving humanoid figurines and other figures composed of concatenated articulated interpenetrating ellipsoids. For such figures, the hidden line algorithm used consists in solving the quartic equations which result from simultaneous pairs of ellipses viz. (a) the projection of the outline of one being drawn, and (b) that of one potentially obscuring it. This is done in terms of Cohen's parameter, resulting in an ordered list of compacted hidden arcs of each outline. The visible outlines are then generated to the required fidelity separately.

Where two ellipsoids interpenetrate, the outline of each is drawn up to the points where it disappears into the other. These points can be found by the simultaneous solution of the ellipse equations of (a) the projection of the outline being drawn, and (b) the projection of the ellipse of intersection of the obscuring ellipsoid with the plane of the outline of the drawn ellipsoid.

The viewing window is assumed to be an ellipse also. Parts of objects projecting outside this ellipse are not drawn.

The number of quartics to be solved is reduced significantly by testing each pair of ellipsoids for non-intersection of projected outlines by comparing the projected separation of centres with the sum of their maximum semiaxis lengths, and taking advantage of the total obscuration of one ellipsoid by another when discovered.
CASS
Authors: Hawrylyshyn P. A. , Tasker R. R. , Organ L. W.
Published: November 2005

An interactive computer graphics system has been developed for online use with a two-stage stereotaxic technique in man. The computer plots sagittal sections approximating the region of the brain being stimulated on a display screen located in the operating room. When responses are elicited by electrical stimulation, they are graphically illustrated on the template, accurately positioned at the brain site being stimulated. If such evoked responses do not fit the template, they can be replotted on a modified template in a manner prescribed by the neurosurgeon. Such a system allows optimal localization of subcortical lesion sites.
Interactive analysis and display of tabular data
Authors: Benson William H. , Kitous Bernard
Published: November 2005

A program for simple data analysis and report design is described. The design emphasizes flexibility, ease of use, and rapid interactive response. These considerations are discussed in relation to the choices that may be made in the analysis and display design process. The analysis may be directed and monitored at several points - data selection and calibration, binning, choice of data scaling, choice of graphic variable, and scaling of the graphic variable. Table rows and columns can be re-organized by operators such as ranking, sequencing and grouping, and re-computed from arithmetic combinations of existing rows and columns. Where the raw data represents different cases scored over the same attributes, profile tables can be computed in a systematic fashion. Interactive report design is supported by a variety of page layout and chart annotation directives, which can be used to embellish and adjust the default line, bar and pie charts. The program can be used interactively as well as driven from a prepared script, and uses a device independent graphic system. Although intended to be used primarily with a graphics terminal, at least half the actual use has been conventional report generation on both alphanumeric and graphic terminals.
A color animation system
Authors: Levoy Marc
Published: November 2005

This paper describes an animation package currently under development at the Cornell Program of Computer Graphics.The basic algorithm employed is linear or non-linear interpolation between successive pairs of key frames. These key frames are composed of artwork input by the animator on a graphic tablet and displayed on either a black and white vector scope or a color halftone CRT. The initial working environment is two-dimensional, and the individual images are combined using a multiplane cel animation technique to produce depth and motion illusions. Real-time film previewing, utilizing an on-the-fly interpolation algorithm, provides the artist with instant playback of animated sequences.
The buffalo crime mapping system
Authors: Brassel Kurt E. , Utano Jack J. , Hanson Perry O.
Published: November 2005

This paper presents the design strategy for a crime information system with vast capabilities for production of and experimentationwith maps. Detailed disaggregated crime information from the city of Buffalo, New York forms the primary data base for the system. This series of crime files, together with socio-economic data from the Census, are integrated into a geographic information system denoted as the Crime Analysis and Research Package (CARP). The Buffalo Crime Mapping System as a part of CARP is a collection of data files and routines designed for versatile display and analysis of spatially referenced crime data. It deals with three types of information: crime, census, and spatial reference information containing various geometrical indices such as block group boundaries and centroids of statistical units. The boundary information is provided by a flexible arc structure. The three major data files are stored as random access files and are interfaced with various display procedures such as choropleth, graduated circle, and dot mapping programs. The user provides the system with a set of instructions as to the desired map type and its display parameters. A-driver routine then reads the map type instruction and calls the appropriate mapping routine. This mapping program then proceeds by reading the user parameters, accesses the necessary base files, and produces the final map. At its present stage, the system is batch oriented and does not provide for interactive and/or real-time communication features.
Trans-use of graphics in the study of transformations
Authors: Hefez E. , Dror L. , Nesher P.
Published: November 2005

The TRANS system is a drill and practice system for the study of transformations of the plane. The system is designed for elementary school pupils (ages 8-10) who have studied the subject in the classroom environment. The system contains exercises on the terms: axis of reflection, reflection, translation and rotation. It is divided into several sections according to increasing difficulty. Each section contains a number of exercises with interesting geometrical shapes to arouse the pupil's attention and interest. The pupil's task is to designate the position of the axis of reflection in order to reflect, translate or rotate a shape to its final position. The pupil's main tool is the light pen. There are additional exercises in which the pupil is presented with a shape, an axis of reflection, and he has to find the reflected shape. The system contains a follow up of the successes and failures of the pupil. If necessary it advises the pupil or gives him hints. At the end of the exercise the pupil receives a grade.
A simple approach to computer aided milling with interactive graphics
Authors: Satterfield Steven G. , Rodriguez Francisco , Rogers David F.
Published: November 2005

This paper describes CAMILL, a system for computer aided milling of ship hull models defined with interactive graphics. The major hardware components of CAMILL are a mini-computer based refresh display and a three axis numerically controlled milling machine. For hardcopy documentation there is a large flatbed plotter. The two major software components are an interactive display program and a cutting program. The interactive display program is the human interface and provides capabilities for creating and modifying the ship design. The cutting program is executed in an intelligent terminal interfaced to the milling machine. The data used by the cutting program is generated by the display program and stored on a magnetic cassete tape. This cassette is transferred to the intelligent terminal for use by the cutting program. The main function of the cutting program is to direct the milling of the desired ship hull.
Visual interaction with overhauser curves and surfaces
Authors: Brewer J. A. , Anderson D. C.
Published: November 2005

The method of parabolic blending for curve and surface interpolation originally conceived by A. W. Overhauser is applied to the interactive free-form design of three dimensional objects. A significant advantage of the algorithm is the user-oriented control of surface shape that is achieved because one interactively manipulates only coordinates on the design surface, as opposed to parametric slopes or design points.The algorithm is demonstrated using an interactive 3D design system that executes in a dual-minicomputer refresh graphics environment without special 3D hardware. The system provides high level data generation commands and direct visual interaction with structured 3D data using a multi-purpose 3D cursor and shaping tool. Objects composed of points, lines, curves and surfaces of different forms may be interactively created and manipulated.
A system for sculpting 3-D data
Authors: Parent Richard E.
Published: November 2005

A major research area in 3-D computer graphics is the inputting of complex descriptions. This paper describes our current attempt at solving that problem: creation of a sculptor's studio-line environment in which the user is provided with various tools to shape, cut and join objects. The emphasis of the implementation has been on naturalness and habitability. The issues involved in designing such a system, especially in a minicomputer-based color raster-scan animation environment, are discussed. The basic algorithms are described in some detail and a fast efficient implementation of a hidden-line algorithm is explained.
Ways of structuring data within a digital cartographic data base
Authors: Edson Dean T. , Lee George Y. G.
Published: November 2005

The National Mapping Program includes the activities for providing basic map data and a family of general-purpose maps. The U.S. Geological Survey is developing a Digital Cartographic Data Base (DCDB) within the National Mapping Program to include such features and reference systems as the public land survey network, State and county boundaries, transportation systems, and hydrography. Although the public land survey network is administered by the Bureau of Land Management, it is included as a DCDB component because of its relationship to almost all cultural development beyond the thirteen original States. Such data included in DCDB have no legal status and are intended for display and map reference only. The interrelationship of these categories, particularly of the first three, requires care in structuring the digitized data so that valuable time is not wasted in producing cartographic spaghetti. This paper presents some ideas about structuring the components of DCDB.
GEO-OUEL
Authors: Berman Richard R. , Stonebraker Michael
Published: November 2005

This paper briefly summarizes the implementation of GEO-OUEL, a special purpose geographic information retrieval and display system. Basically, it is a rather small "front end" to a powerful general purpose relational data base system, INGRES, implemented at Berkeley. Also discussed are the problems that were discovered during the implementation of the original proposal (presented at the 1975 ACM SIGMOD/SIGGRAPH Workshop in Waterloo, Ontario) and the corrective steps taken. Lastly, experiments are described which indicate the performance penalty paid for this "front end" approach and the savings in development time realized.
Hidden surface removal using polygon area sorting
Authors: Weiler Kevin , Atherton Peter
Published: November 2005

A polygon hidden surface and hidden line removal algorithm is presented. The algorithm recursively subdivides the image into polygon shaped windows until the depth order within the window is found. Accuracy of the input data is preserved.The approach is based on a two-dimensional polygon clipper which is sufficiently general to clip a concave polygon with holes to the borders of a concave polygon with holes.A major advantage of the algorithm is that the polygon form of the output is the same as the polygon form of the input. This allows entering previously calculated images to the system for further processing. Shadow casting may then be performed by first producing a hidden surface removed view from the vantage point of the light source and then resubmitting these tagged polygons for hidden surface removal from the position of the observer. Planar surface detail also becomes easy to represent without increasing the complexity of the hidden surface problem. Translucency is also possible.Calculation times are primarily related to the visible complexity of the final image, but can range from a linear to an exponential relationship with the number of input polygons depending on the particular environment portrayed. To avoid excessive computation time, the implementation uses a screen area subdivision preprocessor to create several windows, each containing a specified number of polygons. The hidden surface algorithm is applied to each of these windows separately. This technique avoids the difficulties of subdividing by screen area down to the screen resolution level while maintaining the advantages of the polygon area sort method.
A graph-theoretic real-time visible surface editing technique
Authors: Tanimoto Steven L.
Published: November 2005

Efficient visible surface (hidden surface) algorithms must make use of information about the structure of the environment, constraints on viewpoint locations and the coherence between successive views in a sequence. Here the visible surface problem is posed as a problem in graph theory. A new technique based on 'updating cut-sets in a graph is presented as a means to streamline the culling of back faces during visible surface computations. The technique can be used for general environments that contain some convex polyhedra. Since the method saves the most computation when convex polyhedra having many faces appear in the environment, it is particularly appropriate for handling geodesic domes and polyhedral approximations to spheres. A direct extension for nonconvex polyhedra is suggested.
A homogeneous formulation for lines in 3 space
Authors: Blinn James F.
Published: November 2005

Homogeneous coordinates have long been a standard tool of computer graphics. They afford a convenient representation (for) various geometric quantities in two and three dimensions. The representation of lines in three dimensions has, however, never been fully described. This paper presents a homogeneous formulation for lines in 3 dimensions as an anti-symmetric 4x4 matrix which transforms as a tensor. This tensor actually exists in both covariant and contravariant forms, both of which are useful in different situations. The derivation of these forms and their use in solving various geometrical problems is described.
Computer art for computer people - a syllabus
Authors: Hertlein Grace C.
Published: November 2005

Given the present state of the art, it is easier to introduce and teach computer art to people who have some background in computer science. Although there are many art-oriented systems for non-programmers, a study of the work of these artist-students reveals that their final products do not surpass the work of programmer-artists. Experience in working with artists and non-programmers during the past seven years has repeatedly shown that computer people, with special guidance and instruction, can and do produce professional looking computer art works that rival and often surpass the works of intermediate to advanced artists who engage in this new medium. However, working with Computer Science people poses unique requirements. Although they produce professional looking works within one semester, their orientation is dominantly practical, and often they will abandon their artistic efforts after the conclusion of their course of study, to aim at more practical, job-oriented skills. This paper describes in detail the course objectives, and includes a listing of lecture/discussiontopics, and offers the reader a schedule of week-by-week presentations and explorations for development in laboratory sessions.
Typer
Authors: Sonderegger Richard P.
Published: November 2005

After experiments with more traditional editors, TYPER, an editor designed specifically for the online composition and editing of text, was developed. TYPER uses the 20 lines of a CRT terminal screen to implement a window onto the writer's text that can be moved at will. All normal typewriter functions are available plus special functions for the easy insertion, deletion, and modification of text. A non-destructive cursor can be moved about the screen and acts as a pointer to the text. Any printable character typed is immediately placed in the text at the position indicated by the cursor and the change is reflected on the screen. Insertion and deletion of text is accomplished with simple keystrokes. After an insertion or deletion, any extra space between words and space at the end of short lines is filled by "closing" the text. Successive words are placed so that they are separated by one space and extra space at the end of a line is filled with words from the succeeding line.Response to TYPER has been excellent. Non-programmers and even those with no computer experience learn its use quickly and are loath to go back to typewriters after using it. In addition, programmers are using it to edit their program code.
Sequential/parallel matrix picture languages
Authors: Wang Patrick Shen-Pei , Grosky William I.
Published: November 2005

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

This paper describes an advanced technique in hardware and software for the intermixed display of refresh and storage graphics. Traditional storage tube terminals have the advantage of low cost coupled with the ability to display large amounts of high resolution graphic information, but do not provide for dynamic motion and transformation of a displayed image. High resolution, high density refreshed displays tend to be expensive. Combining both refresh and storage graphics on the same display allows pictures to be segregated into static and dynamic areas to achieve the desired results at reduced cost. The hardware and system software to make this marriage of refresh and storage graphics work effectively for interactive computer graphics is described.
Computer-generated stereograms
Authors: Morland D. Verne
Published: November 2005

The discovery of stereopsis in the mid-nineteenth century presented the opportunity to simulate the visual impact of a three-dimensional entity through a pair of two-dimensional, perspective images. Modern image processing techniques now permit the extensive exploration of abstract stereograms, but most recent investigations have focused on scientific rather than aesthetic compositions. This paper describes a complete svstem for the creation of stereo artwork and discusses the implications of using stereoscopy for artistic, "three-dimensional expression.
A conversational extensible system for the animation of shaded images
Authors: Baecker Ronald M.
Published: November 2005

The terms "conversational" and "extensible" are defined and shown to be useful properties of computer animation systems. A conversational extensible system for the animation of shaded images is then described. With this system, implemented on a minicomputer, the animator can sketch images and movements freehand, or can define them algorithmically via the Smalltalk language. The system is itself implemented in Smalltalk, and hence can be easily extended or mcdified to suit the animator's personal style.
Experiments with computer animation
Authors: Negroponte Nicholas , Pangaro Paul
Published: November 2005

Three generally accepted facts are:1. Computers are getting cheap and fast enough to do cost-effective graphics on line and in real time;2. The future of computer graphics is in raster scan;3. Computer animation is emerging as a volatile art form and as a medium for scientific communication.Concurrently, we find computer animation somewhat polluted and distorted by1. The illusionary immediacies of analog techniques;2. The line gestalt of computer output microfilm;3. The transformational paradigm of the 4 by 4 matrix.In contrast, this paper dwells on on-line, real-time, color rasterscan, digital techniques and associated videotapes. Accompanying illustrations present the specific application of a "veridical memory" approach to computer graphics, distinguished from other similar efforts by:1. A 90 nano-second, writable control store;2. Noncontiguous and variable bits per pixel;3. Minicomputer support of PL/1, LISP, and LOGO;4. Advanced graphical input techniques;5. Hardware priorities indigenous to cell animation;6. Production of color hard copy.Results indicate an opportunity for complex descriptions and displays1. In which the message is not the medium;2. Through which color assumes a new role;3. With which the user works without a typeable genre;4. About which our wildest fantasies offer only modest extrapolation.Inasmuch as our work on animation is just beginning, this paper does not take a rigorous posture. Instead, we submit a collage of output, classify some of our errors, and outline likely solutions.
Interacting with the GALATEA film analysis system
Authors: Potel M. J. , Sayre R. E.
Published: November 2005

GALATEA is an interactive animated graphics system providing a tool for the man-machine analysis of moving images recorded on film. The system relies on the user's recognition of phenomena of interest and his manipulation of simple graphical objects to build up a kinegram, an animated representationof the film. Display of the kinegram superimposed on the original film facilitates the entry and refinement of the animation. The net result is an analysis by synthesis. In this paper we describe the current production version of GALATEA from the standpoint of the user. Included are a functional description of the constituent hardware, demonstration of various aspects of system behavior, and some examples of interactions common in user applications.
A summary of graphics terminal requirements based on application studies
Authors: Carlson Eric D.
Published: November 2005

Decreasing costs of graphics hardware, improvements in graphics software, and establishment of online data bases are increasing the interest in computer graphics. For new applications of computer graphics to be developed and used, the graphics terminal must meet the requirements of users and applications. Because many of the users will be nonprogrammers and the interactions will involve pictures, the applications are significantly different from those currently supported by batch computing or alphanumeric terminals. Studies of users, applications, and implementations of interactive computer graphics systems have resulted in thirty specific requirements for the display screen, the associated hardware for input, output, processing and storage, the interaction rates, the terminal packaging, and the support of the applications programmer. Comparison of existing graphics terminal alternatives in terms of the requirements indicates that eighteen of the thirty requirements are provided inadequately. Comparison of the relative importance of the requirements for different classes of applications indicates that color, image mixing, hard copy output, portability, upward compatibility, and reduced reflection, glare, and noise would be the most useful terminal improvements for developing new applications of computer graphics.
The HRD-1 laser display system
Authors: Woodsford P. A.
Published: November 2005

The Laser-Scan HRD-1 is both a large screen, high resolution interactive storage display and a high quality precision film plotter. It is therefore relevant to both the interactive editing and the production aspects of computer graphics systems, and its characteristics are particularly suited to application areas such as automated cartography, in which large amounts of graphical data have to be displayed and manipulated.
Interactive computer graphics for computer aided design in civil engineering
Authors: Wilson John L. , Lansberry Charles R.
Published: November 2005

Interactive computer graphics can be an effective and efficient aid in the analysis/design cycle of engineering problems. The vistas of much engineering research and design can be expanded with the tools and methodology available with the introduction of an interactive computer graphics (ICG) system into an academic or industrial environment. Specific attention is given in this paper to new areas of application of ICG in civil engineering; guidelines for the planning of ICG systems; practical applications in bridge design and shipbuilding; and economic considerations involved in using ICG systems.
Controlling user interaction
Authors: Kasik David J.
Published: November 2005

The user of an interactive application is in an anamolous position, especially if he is not one of the elite class known as "computer bums". This mythical user is at the end of a process totally controlled by a computer and a program. His communications with the program may suffer greatly because of this total dependence.Control of communication in the batch environment is much more a one-way street. Here the user supplies the program data, and the batch program informs him if something has gone wrong by evicting his run from the machine. The user then consults available documentation (if it exists) or a computer expert (if one exists) for help in solving the problem. The communication between program and user is not critical in this environment; the user is expected to know what to do before he starts the run and can seek assistance outside of the computer.The interactive environment, however, has the user totally at the mercy of the program for diagnostic and prompting information. Even sophisticated graphics-oriented applications, which provide large amounts of useful information through pictures, may not adequately control the user's interaction. The user needs direction imposed on him to successfully solve his problem. At the same time, the system must provide flexibility, i.e., he must not be constrained to a single path of action that may only suit the code's implementor. No user's manual can capture a flow of this nature because of the inherently static nature of words on paper. Furthermore, paging back and forth in a manual to decipher what is to be done next destroys the spontaneity implicit in a successful interactive system.The user must be the main concern of the interactive system for it to be successful. With this goal in mind, Battelle-Columbus has developed a structured approach to controlling user interaction. The approach benefits the implementor as well as the user. It places emphasis on design and checkout of interaction as the first, rather than the last, step in an interactive application.
BGRAF2
Authors: Bergman S. , Kaufman A.
Published: November 2005

The BGRAF2 language for interactive real-time 2D graphics was designed as a user-oriented language emphasizing ease of use rather than of implementation. Procedural statements allow straightforward computation while classlike characteristics encourage modular graphics programming. The clock and event data types facilitate creation of parallel and synchronous procedures automatically acting on structures and display files. A graphic procedure, which includes procedural, drawing and event-driven statements, is a graphic prototype. Such procedures may be nested and iteratively or recursively called. An individual invocation of a procedure, called a graphic object, shares code while commanding its own data structures and images.
A developmental system for microcomputer based intelligent graphics terminals
Authors: Kellner Richard G. , Maas Lynn D.
Published: November 2005

A low cost intelligent graphics terminal for developmental work consisting of a Tektronix storage tube terminal and an ALTAIR 8800 microcomputer is described. The microcomputer system is used to develop and debug customized intelligent terminal configurations and features before a production model is finalized and fabricated. This allows flexibility in terminal design and allows changes to be tried easily before final versions are built. The customized terminal features that are described are the abilities to process a segmented display file, to provide refresh of up to 130 characters or vectors, to control accessory devices such as a flexible disk and a graphics tablet, to provide data compression of over 60% on large pictures, and to provide a local debugging utility.
Cartographic data structures
Authors: Dueker Kenneth J.
Published: November 2005

Means of capturing and encoding cartographic data for machine processing is a major issue in the design and the development of geographic information systems. The available and potential technology constitutes a bewildering array of choices for system designers from which to select formats and processing capabilities to meet user applications. Designers are not provided a very precise statement of data requirements (or fidelity requirements for the data capture and processing system); therefore, the tolerable distortion rates and tolerable information losses are not well expressed so as to assess coding efficiencies. Nor is there substantial agreement as to the appropriate breadth of comparative tests, as some systems can replicate coverages well for cartographic purposes, while other systems may provide stronger analytical capabilities for processing encoded geographic data.One of the major problems in encoding cartographic data is the lack of measures by which to assess the effectiveness of the coding. One set of effectiveness measures relates to the ability to replicate the source document in map form, while a second set of effectiveness measures relates to the use of the map or coverage data. There are a number of effectiveness measures that need developing in order to compare and test the effectiveness of alternative system approaches. A source document constructed to possess features that will test the effectiveness of alternative systems fairly and equitably needs development. This would result in the ability to establish benchmark tests by which systems could be compared.
On the semantics of the assignment statement of high-level graphical languages
Authors: Schrack Guenther
Published: November 2005

Based on the concept of treating graphical data as a data type in its own right with associated language parts and constructs such as graphical constants, graphical variables and graphical expressions, the semantics of the assignment statement of a high-level graphical programming language are investigated in some detail.It is assumed that the graphical data are defined by the areal external representation model. In addition, the semantics of binary operators, the superposition and the deletion operators, are considered.
Experience with distributed processing on a host/satellite graphics system
Authors: Michel Janet , van Dam Andries
Published: November 2005

The problem cf distributing an application between two processors
has been investigated by studying an interactive graphics
application that is divided between a time-shared host computer and
a dedicated satellite system. The division of labor in the
application is determined by a network flow assignment algorithm.
The effect of variation in availability of the host computer on the
distribution of the application is also studied. In particular,
host availability is an important factor in determining the task
distribution. As host availability decreased, procedures miqrate
from the host to the satellite.
Affordability of computer graphics for planning networks in DOD program management
Authors: Potoczniak J. , Kosmin M. , Larkin R. , Callahan J. , Dunn R. M.
Published: November 2005

This report represents data relative to the alternative consideration involved in selecting a configuration for the Interactive Graphics Networking System, (IGNS). The IGNS permits a user to interactively view a network, modify it, if needed, analyze various management options and view their impact upon the data contained in the network, and, finally receive network plots and management reports.A prototype of this system was developed and tested for feasibility. Having proven the feasibility, the purpose of this report is to provide the data necessary for a user to decide the individual optimum system configuration which may be used to facilitate an interactive networking reporting capability.
Automated contouring of vertical oceanographic sections using an objective analysis
Authors: Herman A.
Published: November 2005

This paper describes a group of computer programs developed for contouring vertical sections of oceanographic parameters. The vertical profiles can be constructed from data collected in a variety of ways. The input data for the driver subroutine need not be equally spaced horizontally or vertically. The routines are written in Fortran for a UNIVAC 1108 with an offline Gould Plotter, but can easily be adapted to any computer with a Fortran compiler and a plotter which accepts Calcomp-like commands. The routines are of modular construction.
Characteristics of neuroscience computer graphics displays and a proposed system to generate those displays
Authors: Capowski Joseph J.
Published: November 2005

Computer graphics displays in the neurosciences are classified into three categories: anatomical structures, physiological waveforms, and statistical summaries. The capabilities required in a line drawing system to present neuroscience displays are smooth rotation and translation of 3D structures, simple line rejection, orthographic projection, and flexible interactive hard copy capable of drawing dots. The general purpose computer is available to refresh the CRT. A simple graphics processor with the necessary capabilities is defined and its unique features are discussed.
A method for plotting curves defined by implicit equations
Authors: Cohen Ephraim
Published: November 2005

A square chain of points is found that approximates a plane curve of the form F (x,y) =0. In case F (x,y) =0 represents a conic section, the method requires no multiplication or division, and so is well adapted to hardware or small computer software implementation. The algorithm may also be used to find approximate solutions of differential equations of the form F
1
dx + F
2
dy = 0.
Texture and reflection in computer generated images
Authors: Blinn James F. , Newell Martin E.
Published: November 2005

In 1974 Ed Catmull developed a new algorithm for rendering images of bivariate surface patches. This paper describes extensions of this algorithm in the areas of texture simulation and lighting models.The parametrization of a patch defines a coordinate system which is used as a key for mapping patterns onto the surface. The parametric values within each picture element are input to a pattern definition function. A weighted average of the values of this function over the picture element scales the intensity of that picture element. By suitably defining the pattern function, various surfaces textures can be simulated. The shape and size of this weighting function is chosen using digital signal processing theory.The other problem addressed here concerns lighting models. The patch rendering algorithm allows accurate computation of the surface.
Hierarchical geometric models for visible-surface algorithms
Authors: Clark James H.
Published: November 2005

The research described in this paper addresses the problems associated with the design of systems for efficiently producing computer-generated pictures and picture sequences of very complex, three-dimensional environments. The thesis of the research is that the geometric structure inherent in the definition of the shapes of three-dimensional objects and environments must be used not just to define their relative motion and placement but also to assist in solving many other problems of systems for producing pictures by computer.The implications are that by using an extension of traditional structure information, or a geometric hierarchy, five significant improvements to current techniques are possible. First, the range of complexity of an environment is greatly increased while the visible complexity of any given scene is kept within a fixed upper limit. Second, a meaningful way is provided to vary the amount of detail presented in a scene both according to the screen area occupied by the objects in the scene and according to camera and object motions. Third, by using the geometric hierarchy, "clipping" becomes a very fast logarithmic search for the resolvable parts of the environment within the field-of-view. Fourth, by using this positional hierarchy in conjunction with a storage hierarchy of the sort used in virtual memory computing systems, frame-to-frame coherence and clipping define a graphical "working set", or fraction of the total structure that should be present in primary store for immediate access by the visible-surface algorithms. Finally, the proposed structural framework suggests a new recursive descent visible-surface algorithm in which the computation time grows almost linearly with a scene's visible complexity rather than as a worse than linear function of its object-space complexity.
ARTES
Authors: Gonin Michel-Pierre , Moffett Thurber J.
Published: November 2005

The geometrical definition of a highway alignment is the result of a compromise between two conflicting objectives: keeping within budget limits and providing the user with optimum safety, operating and aesthetic conditions. The interactive graphic console when used as a large computer system peripheral unit is a particularly well-adapted instrument, when properly programmed, to assist the designer in resolving this conflict. It presents him with the appropriate graphical displays representing his design choices and offers him the possibility of modifying these choices as the computer processing progresses. ARTES is such an interactive program. It displays the geometrical elements composing a highway alignment (horizontal alignment, vertical alignment, natural ground and highway cross sections), and displays composed elements such as perspective views and visibility diagrams. It prints out earthworks quantities, plots all graphical elements and enables the program user to modify the geometrical elements composing the alignment thus enabling him to study multiple alternatives affecting construction costs and user conditions.
Computer aided integrated circuit design
Authors: Kozemchak E. B.
Published: November 2005

The design of silicon integrated circuits requires a broad spectrum of computer aids for simulation, physical design, and testing. A CAD approach is described which is both integrated and distributed in nature. The various functions required by circuit designers for simulation, layout, and testing are integrated into a single system, based on a minicomputer (HP21MX) with a storage scope (Tektronix 4014) display. These systems are distributed to provide the design aids in close proximity to users. Approximately forty systems are now employed for the various steps in the design process.
Three-dimensional man-machine interaction
Authors: Clark James H.
Published: November 2005

The film accompanied by this paper illustrates an experimental system for real-time Computer-Aided Geometric Design of three-dimensional parametric surfaces. A detailed description of the system is given in another paper by the author(1). Its principle features are that it operates in real-time, all geometric interaction with the surfaces is accomplished with a 3-D Wand, the surfaces are viewed in 3-D using a head-mounted display, and the surfaces are mathematically represented using parametric spline surface patches.The two principle computing components of the system are a PDP-10 computer and an LDS-1 display computer. The PDP-10 acts as a host to the LDS-1. Its main tasks each 1/30 second are to compute the 3-D Wand and head-mounted display positions and to incrementally update the geometries of the surface patches being designed by the user. During the same time period, the LDS-1 loads its digital matrix multiplier with the room-to-head transformation matrix provided to it by the PDP-10, displays on the head-mounted display's CRT's a line drawn rendering of all of the parametric surface patches that are within the 40 degree field-of-view of the display and displays a small cube to represent the current position of the Wand.The user of the system initiates a design sequence by selecting a patch description file from the PDP-10's file system. He then puts on the head-mounted display and uses the 3-D Wand with its control buttons to grasp the patches, which appear to float before him in the room, and make appropriate changes to their geometry. After a design sequence he may save the new surfaces on the PDP-10 file system and select certain views of the surfaces to be rendered as a continuous-tone shaded picture with hidden-surfaces removed.The first part of the film described here shows the system in real-time operation. During this part, several free-form surfaces are manipulated as the camera records the action on a line-drawing monitor. The second part of the film illustrates a continuous-tone, shaded rendering of a design sequence. The continuous-tone rendering was produced "off-line" using pertinent viewpoint information that was saved during the design sequence. The final few minutes of the film depict the construction of a Klein-Bottle.
The line drawing editor, an experiment in computer vision
Authors: Jarvis John F.
Published: November 2005

A computer program, the Line Drawing Editor (LDE), that allows convenient modification of computer representations of simple line drawings has been designed and implemented. The distinguishing feature of the LDE from the multitude of interactive graphics programs that accomplish the same function is the use of a computer controlled TV camera for input and program control rather than conventional interactive input devices such as light pens or data tablets. A graphical editing language allows the LDE user to indicate, by marking the drawing in appropriate fashion, the changes that are to be made. The drawing, which was generated on a hardcopy output device, with the added edit information is placed in front of the camera. In successive phases the LDE computes a two dimensional homogeneous transformation relating the viewed drawing and its computer description, locates the lines added to the drawing, parses the added lines according to the edit language and finally uses this information to update the drawing description.
A more flexible image generation environment
Authors: Crow F. C.
Published: November 2005

A supervisory process is used to distribute picture-generation tasks to heterogeneous subprocesses. Significant advantages accrue by tailoring the subprocesses to their tasks. In particular, scan conversion algorithms tailored to different surface types may be used in the same image, a changing mixture of processors is possible, and, by multiprogramming, a single processor may be used more effectively. A two-level shape data structure supports this execution environment, allowing top-level priority decisions which avoid comparisons between surface elements from non-interfering objects during image construction.
Anti-aliasing through the use of coordinate transformations
Authors: Turkowski Kenneth
Published: November 2005

The use of the point-line distance in evaluating the 2-dimensional anti-aliasing convolution is studied. We derive transformations of the point-spread function (PSF) that give the effective convolution in terms of the point-line distance when the class of object space primitives is limited to lines and polygons. Because the quality of filtering is embedded in a table indexed by the point-line distance, this approach allows one to use arbitrarily complex PSF's, only the width and not the shape of the PSF affects the amount of computation. We apply the CORDIC algorithm to point-line distance evaluation, and show its merits. Also, we show the more standard use of the CORDIC algorithm for coordinate rotation, polar-to-rectangular and rectangular-to-polar conversion, and calculating the norm of a vector. Rounded end points can be achieved by using the point-segment distance, computational methods are given, including CORDIC implementation. The CORDIC algorithms for the aforementioned geometric operations are prime candidates for VLSI implementation because of their inherent parallel/pipeline nature.