Graphic Devices Research Articles

An Examination Of Techniques For Reformatting Digital Cartographic Data / Part 1: The Raster-To-Vector Process

Current graphic devices suitable for high-speed computer input and output of cartographic data are tending more and more to be raster-oriented, such as the rotating drum scanner and the color raster display. However, the majority of commonly used manipulative techniques in computer-assisted cartography and automated spatial data handling continue to require that the data be in vector format. This situation has recently precipitated the requirement for very fast techniques for converting digital cartographic data from raster to vector format for processing, and then back into raster format for plotting. The current article is part one of a two-part paper concerned with examining the state-of-the-art in these conversion techniques. In part one, algorithms to perform all phases of the raster-to-vector process are systematically outlined, and then compared in general terms. Examples of existing implementations of the raster-to-vector process are also described and evaluated. Part two will outline and compare algorithms to perform the reverse process, vector-to-raster conversion. Part two will also discuss raster-to-vector and vector-to-raster conversion as an integrated process.

Acoustic radar graphic input device

Accurate X,Y position determining digitizers presently require a precision array of wires embedded in the tablet. In rear-projection tablets these wires tend to limit the optical quality of images projected on the screen. Principles of acoustic radar are applied in a device which achieves better resolution, at a lower cost and without the use of wires, either in a tablet or a cursor. The function of acoustic reflectors for automatic calibration is described, achieving an accuracy of + mn; 0.01% of the distance to the sensors. In the case of small tablets, a hand-held stylus may be tracked at the rate of 900 locations a second.

The workstation concept of GKS and the resulting conceptual differences to the GSPC core system

GKS has evolved from a long process of national /1,2,3,4/ and international /5,6/ discussion on standardization of graphical systems. One of the basic principles of the Graphical Kernel System GKS is the concept of workstations that are used to address a display terminal with several input devices. This is a basic conceptual difference to the GSPC core system /6/, which will be discussed in this paper. A workstation represents a collection of graphical devices that are operated in a coordinated fashion by an operator at a given site. The whole workstation is treated in GKS as one logical unit. GKS features two dimensional output to and input from single or multiple workstations. Besides basic line drawing primitives raster graphics primitives are supported. The coordinates are transformed in a two-stage transformation process where the first stage can be set for each primitive and the second can be set for each workstation. Furthermore the setting of a workstation specific pen and text table allows control of the appearance of all primitives on the corresponding workstation. A segment facility provides means for structuring a picture in subparts. Segments may be created and deleted, the segment attributes may be dynamically modified, and the segments may be transformed. They can be displayed simultaneously or alternatively on different workstations. A device independent segment storage serves for inserting segments into other segments.

A real time tv raster scan unit

The development in the field of computer graphics is determined particularly by the progress made in peripheral graphic devices. A graphical terminal should unite the advantages of vector with those of raster graphics; to enable the extensive use of excellent interactive techniques involving higher graphical productivity and low costs. The terminal describes fulfills these preconditions. Is is characterized by large picture structure and interactive communication capabilities at low cost. Terminals having this conception essentially serve to increase the extensive use of computer graphics, above all in the field of computer aided design.

Coal Resource Data Processing, Old and New Techniques: ABSTRACT

The use of data-processing techniques in coal resource evaluation is characterized by a gradual adaptation of computer techniques rather than by any revolutionary breakthrough. The main thrust of the data-processing effort is the use of computers to store and retrieve the large volumes of data associated with core-hole analyses. The data are of two types: (1) assay data from coal seams; and (2) codified lithologic descriptions of the stratigraphic sequence of interest. The automatic contouring of assay isopleths is now a routinely accepted procedure; the limitations of the contouring algorithms have been offset by the ability to generate quickly large quantities of maps. The trend now is toward increasingly sophisticated use of available options such as trend analysis and the different geostatistical algorithms for interpretation, estimation, and classification. In regard to stratigraphic data, the main emphasis is a graphic display of information to aid the geologist in interpreting the stratigraphic sequence. Some attempts have been made to automate the interpretation. In the near future, we expect to see the routine use of interactive graphic devices to aid the geologist in his work. The type of tool envisaged is analogous to the stratigraphic interpretation of seismic records by petroleum explorationists. End_of_Article - Last_Page 684------------

Curve analysis of small-angle scattering by triaxial body models using a graphic display device

An interactive program using a graphic display device for the analysis of small-angle scattering has been developed. It includes the curve fitting of experimental data to theoretical results calculated through a triaxial body approximation.

Tidy Drawings of Trees

Trees are extremely common data structures, both as internal objects and as models for program output. But it is unusual to see a program actually draw trees for visual inspection. Although part of the difficulty lies in programming graphics devices, most of the problem arises because naive algorithms to draw trees use too much drawing space and sophisticated algorithms are not obvious. We survey two naive tree drawers, formalize aesthetics for tidy trees, and descnbe two algorithms which draw tidy trees. One of the algorithms may be shown to require the minimum possible paper width. Along with the algorithms proper, we discuss the reasoning behind the algorithm development.

Filling algorithms for raster graphics

Two algorithms for filling irregular polygons are presented. They are both oriented towards raster graphics devices and use the refresh memory for part of their working space. One of them always does the filling correctly, unless the contour has an “impossible” topology (e.g., similar to the letter θ), and even then does not produce any leaks outside the external part of the contour. The other algorithm does the filling correctly only if the contour has no triple points, i.e., pixels which are common to three arcs. The first algorithm can be implemented in practice only within the microprocessor controlling the display, while the second can be implemented easily in the host computer and can use the refresher memory only for storage. Some of the simpler (and obvious) algorithms are discussed for comparison. The proposed algorithms do not use decomposition into simpler polygons. They can easily be adapted for shading according to any preassigned rule.

The computer and eye processing pictures: The implementation of a raster graphics device

The process of solving visual analogies was examined using a digital video display and video-based eye tracker. The results indicated that increasing the complexity of an analogy by increasing the number of relations involved in the problem resulted primarily in increasing the time it takes to discover the mapping between the two members of the first pair. The display of the picture and the analysis of the eye fixations are described.

A graphic system utilizing an associative data structure

This paper describes design and implementation of a graphical information system consisting of an associative data structure and a device-independent graphical system built on top of the data structure. The data structure describes logical associations in terms of binary relations based on the concept of triples “attribute-object-value” and in terms of mathematical sets. The main characteristic of this structure is that it is fully dynamic; its data contents, the logical structures connecting the data, and even the physical size of the structure are allowed to change with time in a completely free way. With the help of the data types and operations provided by the data structure, a logical structure is built up that is able to represent three-dimensional geometric structures in a form that is completely independent from any type of graphical device. By adding specific device drivers to the system, the same graphical data can simultaneously be displayed on different graphical devices. An interpreter allows to define and manipulate logical and/or graphical structures and to perform retrieval on them with the help of a simple but powerful assembler-like language. Possible extensions of the system are discussed briefly and related to similar developments. The work reported here has been done in a project being a cooperation between the Technische Hochschule Darmstadt (THD), Fachbereich Informatik, Forschungsgruppe Graphische Datenverarbeitung, and the Universidade Estadual de Campinas (UNICAMP), Faculdade de Engenharia, Departamento Elétrica/Eletrônica, Grupo de pesquisa em Controle de Processos por Computadores, under the coordination of Prof. Dr. J. Encarnaçao (THD) and Prof. Dr. M. Mendes (UNICAMP), sponsored in Germany by the Gesellschaft für Mathematik und Datenverarbeitung mbH (GMD) and Projekt Prozesslenkung mit DV-Anlagen (PDV), and in Brazil by Conselho Nacional de Pesquisas (CNPq), as specified in the UNICAMP-FEC-Report 10/1975.

Fast digital vector- and circle generator with binary rate

Digital graphic generators can be used as interfaces to different graphic output devices such as plotters, vector and raster-scan displays. The principle of digital vector and circle generation with binary rate multipliers (BRM) is represented. There is given a formula which describes the discrete approximation of the ideal BRM function.

A simply extended and modified batch environment graphical system (SEMBEGS)

SEMBEGS is a complete batch environment graphical system containing components for handling graphical data files, for displaying the contents of these files on a variety of graphical hardware, and for performing graphical batch input operations. SEMBEGS is easy to extend and modify to meet the growing needs of a large batch environment, and is even extendable to a fully interactive system. The paper presents the conceptual view of graphics leading to the design of SEMBEGS and outlines the major components of the system. The design of SEMBEGS is founded upon the basic assumption that the true aim of computer graphics is to describe graphical entities, rather than, as commonly held, to provide graphical input and output functional capabilities. SEMBEGS is built around a Basic Graphical Data Management System (BAGDAMS) which provides a common means of communicating the descriptions of graphical entities between the various components of SEMBEGS. BAGDAMS provides facilities for storing, retrieving, and manipulating the descriptions of graphical entities provided by, and received by application programs, graphics packages, and graphical devices.

Interactive Graphics Devices [Guest editor's introduction

The new user of interactive graphics systems probably doesn't know much about the tradeoffs and options involved with using interactive input/output equipment. And there are few sources of introductory material on the subject. This issue attempts to provide such a source.

An implementation of the ACM/SIGGRAPH proposed graphics standard in a multisystem environment

Los Alamos Scientific Laboratory (LASL) has implemented a graphics system designed to support one user interface for all graphics devices in all operating environments at LASL. The Common Graphics System (CGS) will support Level One of the graphics standard proposed by the ACM/SIGGRAPH Graphic Standards Planning Committee. CGS is available in six operating environments of two different word lengths and supports four types of graphics devices. It can generate a pseudodevice file that may be postprocessed and edited for a particular graphics device, or it can generate device-specific graphics output directly. Program overlaying and dynamic buffer sharing are also supported. CGS is structured to isolate operating system dependencies and graphics device dependencies. It is written in the RATFOR (RATional FORtran) language, which supports control flow statements and macro expansion. CGS is maintained as a single source program from which each version can be extracted automatically.

Interactive control of graphic output devices

A software package for the support of graphic output was developed. The main feature is the capability to draw graphs in a Cartesian coordinate system. With up to 60 variable parameters, it is problematic to change them interactively. Classical program languages do not support interaction. Subroutines for various kinds of input had to be written. Most important are other subroutines for reading, writing or erasing datasets at runtime, the name of which need not be known before starting a program. According to the problems, different appropriate methods of dialogue were used: the simple sequential dialogue, command languages and, for more complex input, a syntax analyser. The resulting dialogue is very simple and self-explanatory. The users need not have previous experience with computers; the package was accepted quickly and is now in extensive use.

G-plot: graphics in the geological computer

G-PLOT is a package of programs for graphic display of data. It has been designed as an integral part of the G-EXEC data-handling system, and adopts the principles of G-EXEC: it is generalized with respect to data, it is structured and modular, and it has a simple (near-English) user interface. In addition, a number of standards have been defined to allow the greatest possible flexibility of usage of the programs, as well as to provide a consistent and powerful set of modules for the applications programmer. The two most significant of these standards are the use of the ‘plot-frame’ concept and the definition of logical raster levels between the data and a ‘logical plotter’. By the use of these standards, it is possible not only to send generated plots to any available graphic device, but also to edit plots by selection and manipulation of logical ‘subframes’—units of plot data such as axes, titling, map frames, and grids. By the combination of G-PLOT facilities with planned enhancements to the G-EXEC system, it will be possible to generate sequences of plot frames from iterative simulation models, or from successively changing parameters (scaling or rotation for example) in normal application programs.

Exploratory Analysis of Aggregate Voting Behavior: Presidential Elections in New Hampshire, 1896–1972

This paper presents a new statistical method that is well-suited to building and testing theories of change. An exploratory, robust two-way analysis of New Hampshire’s county-level presidential election returns for the past eighty years illustrates how this general technique can help to clarify theoretical concepts as well as to reveal systematic regularities in empirical data.Because two-way analysis involves a number of novel techniques, this paper is primarily a methodological exposition. It devotes much more attention to step-by-step details of how the analysis was carried out, and the accompanying exhibits contain much more detailed information than normally would be the case for reporting results of such research.In contrast to classical methods, the techniques presented in this paper are intended primarily for exploration of data rather than for statistical inference. They require very few assumptions about the data, and they are not unduly influenced by extreme or missing values. Graphic and semi-graphic devices keep the analyst close to the data and make it possible to display many numbers simultaneously in contrast to simple single-number summaries which can conceal information. Removing obvious regularities in the data facilitates discovery of other underlying patterns.

An interactive graphical minicomputer system for the management and exploration of clinical renal data

A minicomputer system has been developed to help the management and assimilation of multi-variable clinical data for renal dialysis and transplantation. The system employs a variety of peripherals including graphical devices to clarify the trends and correlations in data. To implement a practical system capable of real benefits, it proved necessary to write an extensive system of interlocking applications tasks. The structure and organisation of these tasks is described.

DSPOBJ—System for display of multiple sets of three-dimensional data

DSPOBJ, a subroutine that allows the viewing of several sets of three-dimensional line networks interactively on an Evans and Sutherland Picture System, is described. A menu of functions displayed on the screen provides interactive control of the rotations, translations and scale in all axes of each set as a separate object or all sets simultaneously as a single object. Additional features include reflection about each axis, variable depth cross-sectioning, trimetric or perspective projection, and a split screen consisting of a front, side and top orthographic view and the interactively-defined view. The manipulations of the transformation matrices are described. DSPOBJ and its support subroutines are coded in FORTRAN and utilize the Evans and Sutherland graphic support software. Software emulation of the Picture System hardware functions would allow the use of this code on any vector graphics device.

Disk generators for a raster display device

A simple modification of Horn's circle drawing procedure yields a disk generator for a class of graphic devices capable of drawing rectangular areas. Another variation produces a disk a scan-line at a time, allowing it to be drawn at the refresh rate of the display. The calculations involve only additions and binary shifts.