Showing papers on "Graphics published in 1979"

Tv graphics and mixing control

Abstract: A system employed in a television receiver for decoding and displaying graphics information such as may be encoded on a broadcast video signal. The system includes a graphics signal decoder supplied with the encoded video signal, and a plurality of transmission gates responsive to logic control signals derived from outputs of the decoder. The gates are coupled to inputs of video output stages in the receiver, and operate in response to the control signals for interrupting normal video signals to the video output stages and for enabling a voltage representative of a graphics display intensity level to be coupled to the video output stages when graphics information is to be displayed.The system also includes a graphics level control network. The level control network limits excessive graphics representative beam current levels to prevent image defocusing and kinescope screen burn. The level control network also adjusts the graphics display intensity level in accordance with the level of image representative video signals in a mixed video plus graphics display mode, to preserve a desired contrast relationship between the displayed video and graphics information.

Towards an interactive high visual complexity animation system

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

Color table animation

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

A system for interactive electron image calculations

Abstract: An interactive electron-image calculation system has been developed. The system contains all the necessary programs to model interactively a crystal structure and calculate and display the image on a graphics terminal.

Digital graphics generation system

Abstract: A real time digital graphics display system is disclosed for generating circles, arcs and vectors. The system utilizes Taylor's formula to determine the successive coordinates of the points along the image of the character displayed. The system is able to display a given graphical character once given the coordinates of a start point, an end point and the number of increments to be displayed if an arc is to be displayed.

Method of diagnosing errors off-line in pipe specification files of a computer-aided graphics system

Abstract: A method of updating pipe specification files of a computer-dominated piping graphics system, off-line. Interactive cross-checking of new data increases likelihood of effective, later batch operations.

Raster graphics for interactive programming environments

Abstract: Raster-scan display terminals can significantly improve the quality of interaction with conventional computer systems. The design of a graphics package to provide a “window” into the extensive programming environment of interlisp is presented. Two aspects of the package are described: first, the functional view of display output and interactive input facilities as seen by the programmer, and second, the methods used to link the display terminal to the main computer via a packet-switched computer network. Recommendations are presented for designing operating systems and programming languages so as to simplify attaching display terminals.

Digital video display systems and dynamic graphics

Abstract: Most digital video display systems have been capable of producing only text or static imagery. This paper shows that these limitations are not intrinsic to the technology, but are rather a direct consequence of the display system architecture. The paper begins by summarizing some of the background required to understand digital video display systems. The state-of-the-art is then surveyed, supported by an extensive bibliography. Existing systems are described in terms of a methodology which clarifies the effect of system architecture on capabilities and performance. It is shown how dynamic graphics capabilities can be provided if systems adhere to one or the other of two possible architectures. Examples of such systems are presented.

An expandable multiprocessor architecture for video graphics (Preliminary Report)

Abstract: Presented is the design of a flexible expandable multi-processor system for video graphics and image processing. The design involves a central controller which broadcasts data to a variable number of independently executing processing units, each of which in turn controls a variable number of memory units among which the video (frame buffer) image is distributed. An interleaved addressing organization of the video memories guarantees both an even workload distribution as well as maintenance of image coherence for each processing element. Execution speed and image resolution can be independently altered (at any time) by varying the number of processing and memory units. Sample applications of the system—for rapid line drawing and “electronic scene generation” (visible surface algorithms)—are described. Variations of the design for low cost and for powerful, real-time configurations are outlined.

Factors Affecting Traceability of Lines for Tactile Graphics.

Abstract: To facilitate appropriate line choice for tactile graphic displays, 42 visually impaired subjects traced four types of tactile lines in a simple display (without intersections), and in a complex display (having intersections). The lines were single smooth, double smooth (1/4 in. [.635 cm] spacing), single rough, and double rough. Measures were taken of time to complete the task, “behaviors” other than the continuous tracing of a line, and “restarts,” in which subjects required assistance to complete the task. The results indicate which line types may be more readily traced in displays with and without intersections.

SoftCel - an application of raster scan graphics to conventional cel animation

Abstract: The system described uses frame buffers to provide digital analogues to the traditional processes of copying pencil drawings onto cels, painting them, and photographing them. The copying process is replaced by scanning the pencil drawings with a television camera and digitizing the video signal. Several image processing operations are performed on the digitized drawings to condition them for the next step, interactive painting of the drawings mediated by a computer program. The painted drawings are then combined with each other and painted backgrounds for frame by frame recording on film or video tape.

The Instructional Effectiveness of Three Levels of Graphics Displays for Computer-Assisted Instruction.

Abstract: : To date there is little evidence to support the widespread belief of educators and trainers that the use of visual displays enhances instructional effectiveness. This lack of supporting data is critical when computer-based education systems are considered training delivery vehicles; systems capable of providing sophisticated graphics displays are costly. The purpose of this experiment was to obtain data comparing the instructional effectiveness of three types of graphics displays for computer-assisted instruction (CAI). Three groups of subjects each studied one of three versions of a CAI lesson on the psychophysiology of audition. The text of the lesson was identical for all versions; the type of graphics used in the lesson was different for each group. No control group was used. Graphics were either low level (schematic representations and boxed alphanumerics), medium level (line drawings), or high level (animations plus line drawings). After completing the lesson, all subjects were tested for retention of four knowledge categories addressed in the lesson: acquisition and use of principles, identification of structures, definitions and use of terminology, and memory of specific facts. Results indicated that the type of graphics used during the CAI lesson did not affect lesson completion time or final performance on the retention tests.

Characterizing chemical systems with on-line computers and graphics

Abstract: Incorporating computers and graphics on-line to chemical experiments and processes opens up new opportunities for the study and control of complex systems. Systems having many variables can be characterized even when the variable interactions are nonlinear, and the system cannot a priori be represented by numerical methods and models. That is, large sets of accurate data can be rapidly acquired, then modeling and graphic techniques can be used to obtain partial interpretation plus design of further experimentation. The experimenter can thus comparatively quickly iterate between experimentation and modeling to obtain a final solution. We have designed and characterized a versatile computer-controlled apparatus for chemical research, which incorporates on-line instrumentation and graphics. It can be used to determine the mechanism of enzyme-induced reactions or to optimize analytical methods. The apparatus can also be operated as a pilot plant to design control strategies. On-line graphics were used to display conventional plots used by biochemists and three-dimensional response-surface plots.

An Area Shading Graphics Display System

Abstract: A computer graphics display system for rapidly shading areas on a raster scan screen is described. With the system, the host computer provides the display controller with the parameters of a set of component trapezoids which cover the area to be shaded. The paper gives an algorithm for use in the host to decompose an arbitrary polygon into component trapezoids and it describes a microcomputer based controller to shade the trapezoids.

Data acquisition software for high data rate experiments

Abstract: A computerized perceptual laboratory operates a variety of stimulus devices, including static and dynamic graphics displays, and records both discrete and analog data in a diverse and complex set of experimental paradigms. The software requirement to accommodate this variety of paradigms and high input and output data rates has been met by a single multitasked acquisition program that interprets unitary event commands to display graphics or nongraphics stimuli, record responses, control timing, or provide appropriate feedback. Event lists are created and modified with a text editor, then assembled into binary experiment definition files by dialogue with a parsing program. Graphics stimuli are referenced by a file name that contains stimulus attributes for later data extraction. All protocols and stimulus files are loaded prior to the block of trials, so no disk accesses that would delay events are required during a block. The resulting data file contains a record of all variable stimulus and timing information, as well as the discrete and analog responses, in a uniform format which facilitates data extraction.

Digital video display systems and dynamic graphics

Abstract: Most digital video display systems have been capable of producing only text or static imagery. This paper shows that these limitations are not intrinsic to the technology, but are rather a direct c...

SoftCel - an application of raster scan graphics to conventional cel animation

Abstract: The system described uses frame buffers to provide digital analogues to the traditional processes of copying pencil drawings onto cels, painting them, and photographing them. The copying process is...

An interactive documentation system

Abstract: Most chronic users of time sharing computer systems are familiar with programs that allow the creation and manipulation of text files. Less often they have at their disposal programs that will format the document described by a text file, generating output such as a typist might produce. Rarely is there any mechanism by which graphics can be integrated with text. Lawrence Livermore Laboratory has a powerful, flexible and interactive computer-based documentation system that will format a source document description according to user specifications and incorporate illustrations to produce online documents, offset reproduction masters, 35mm color slides, movie titles, or viewgraphs. The flexibility of the system is greatly enhanced by the use of a device independent graphics library. Text may be plotted using the hardware characters specific to a device (when possible), or may be drawn as Hershey characters or polygonally outlined symbols. Illustrations may be defined in a simple 2d graphics language, and graphical output from application programs may also be incorporated directly into a document.

Television display of data or graphics

Abstract: A system employed in a television receiver for displaying graphics information, such as may be encoded on a broadcast video signal, instead of or along with an image represented by such signal. The system includes a graphics signal decoder (27) supplied with the encoded video signal. The decoded graphics signal, instead of being used to drive the video output stages (16) of the receiver, are used as control signals (MONO, R.G.B) for a plurality of transmission gates (31-36) coupled to inputs of the video output stage (16). When graphics information is to be displayed, these gates operate in response to the control signals to interrupting normal video signals to the video output stage (16) and to provide to it instead a voltage (VA) representative of a graphics display intensity level. The system also includes a graphics intensity level control network (25) which limits excessive graphics representative beam current levels to prevent image defocusing and kinescope screen bum. It also adjusts the graphics display intensity level in accordance with the level of image representative video signals in a mixed video plus graphics display mode, to preserve a desired contrast relationship between the displayed video and graphics information. The level control network (25) also enhances the leading and trailing edges of displayed graphic characters by forming a black outline at these edges.

Interactive Computer Graphics: Flying High Part II

Abstract: The growth of computer graphics is remarkable even by computer industry standards. This first of a two-part article views some of the latest hardware available from leading graphics manufacturers.

MOVIE.BYU—A Computer Graphics Software System

Abstract: A nonexhaustive list of attributes for general purpose computer graphics display software systems is formulated and then compared with the operational capabilities of the MOVIE.BYU system. While judgements made concerning the merits of the system depend upon the weight given to the various attributes by a potential user, the system is shown to possess a broad spectrum of capabilities.

Some raster graphics extensions to the Core System

Abstract: The Core System is a proposed standard subroutine package for line-drawing graphics. We present some Core System extensions for use with raster graphics equipment. The extensions, which are upward-compatible with the present Core System, provide filled polygons, display of arrays of pixels, use of a color look-up table, and hidden-surface or hidden-edge removal. The extensions are being intergrated into an existing Core System implementation.

The use of VIEWIT and perspective plot to assist in determining the landscape's visual absorption capability

Abstract: The concept of Visual Absorption Capability (VAC) is widely used by Forest Service Landscape Architects. The use of computer generated graphics can aid in combining times an area is seen, distance from observer and land aspect relative viewer; to determine visual magnitude. Perspective Plot allows both fast and inexpensive graphic analysis of VAC allocations, for project use.

Computer graphics for large scale two- and three-dimensional analysis of complex geometries

Abstract: A comprehensive set of programs have been developed for analysis of complex two- and three-dimensional geometries in the Mechanical Engineering Department of the University of California's Lawrence Livermore Laboratory. State of the art finite element and hydrodynamic codes are being used for the analytical portion of the work. To assist the analytical effort, several additional codes which depend heavily on graphics have been developed. These are basically used for the pre- and post-processing of the data. Prior to running any analysis, the geometry of the body of interest must be represented in the form of small “finite elements”. After the analysis is run, the data must be post-processed. Both spatial and temporal data exist in the database. It is the database between the analysis codes and the post-processors which allows a wide variety of analysis codes to use the same post-processors.The temporal plotting codes produce time histories for specified quantities (i.e. temperature, pressure, velocity, stress, etc.) at various locations within the body. They may also produce cross-plots of these variables (i.e. stress vs strain at a particular position). For plotting of the spatial data two codes are used. The first is for two-dimensional geometries and the second is for three-dimensional models. For three dimensions, the Watkins' hidden surface/line processor is utilized for plots. The spatial plotters will display contour lines on vector output devices and color fringes (or gray values) on raster output devices. They both may also display deformed geometries. Further the three-dimensional code has extensive animation capabilities for movie productions. These graphics codes are used with a wide variety of analyses codes and form a very comprehensive package for the engineering analysis of two- and three-dimensional bodies.