Evaluation of Standard Graphics Packages

In order to compare the quality of different implementations of GKS, the ISO0 standard for computer graphics, an evaluation method for GKS implementations is presented. It is based upon several groups of criteria. One group of criteria is concerned with performance, by which we understand here the memory requirements and time requirements for programs using GKS functions. A program that measures the performance of GKS packages is presented. Results of this evaluation method with several commercially available GKS implementations are described in summary. A checklist for evaluation of standard graphics packages is added as an appendix.     

Two approaches to on-line graphics systems

This article describes two types of software systems which provide an interface to users who wish to apply the power of interactive graphics to their specific problem. The systems are based on an 8K IMLAC PDS-1 minicomputer CRT display which provides sufficient processor power to handle display generation, management, and dynamic manipulation. The minicomputer software was first designed as an independent operating system which not only provides the user with high-speed timesharing access to the host computer, but also the resources of the local processor and its associated input/output devices. In this configuration, host compiled FORTRAN IV programs are loaded into the minicomputer through the timesharing link and executed independently from the host processor. A higher degree of processing is provided by the master-slave relationship between a local DEC PDP $\text{11}\text{40}$ minicomputer and the IMLAC. The user's FORTRAN IV program, executing in the PDP $\text{11}\text{40}$, directs an IMLAC graphics subsystem through subroutine calls. These systems provide the programmer with a foundation for a broad range of high level applications involving computer graphics.     

GKS certification—An overview

The rapid emergence of GKS implementations indicates the widespread acceptance of GKS as an international standard for computer graphics. It is essential however if the interests of the standard are to be preserved, that there be a feasible means of validating GKS implementations to ensure that adherence to the standard is maintained. This paper describes an overall methodology for GKS certification, and outlines in more detail the validation of data returned by GKS to an application program. Validation of output generated by GKS is discussed in general terms in this paper, and in more detail in other papers in this issue.     

GKS Programming in a PHIGS Environment

GKS is an international standard for the functional interface to 2D graphics, whilst PHIGS is currently an ISO work item for 2D and 3D graphics. In addition, PHIGS allows improved control over structuring graphics data in the system. With a new work item, the upwards compatability from GKS to PHIGS is being called into question. This paper is an attempt to give direction to these discussions by listing the implications of introducing a software layer between a GKS application program and a PHIGS environment on which this application is to be run. It is intended to highlight differences between the systems and to answer questions such as, “How compatible?”, “Is it possible?”, “How much does the software layer have to do?”, etc.     

Development and applications of an interactive digital filter design program

We have implemented an interactive digital filter design program in the HP 1000 computer at the Department of Electrical Engineering of the University of Washington. This program allows users to design different types of filters interactively with both amplitude and phase responses displayed on graphic devices. The performance of each designed filter can be evaluated conveniently before the best one is chosen and implemented for any particular application. This program can design recursive filters, e.g. Butterworth, Chebyshev and elliptic, or nonrecursive filters with one out of six different windows, i.e. rectangular, triangular, Hann, Hamming, Blackman and Kaiser. The main outputs from this program are coefficients of a transfer function of an analog filter, a digital filter, or both. Therefore, the design of both analog and digital filters is facilitated by using this program. The program is very simple to use and does not require background in analog or digital filter principles in order to run it. The program is written in standard FORTRAN and is about 30 kbytes in size excluding the graphics display routines. Since it uses standard FORTRAN, it can be easily transported to minicomputer and microcomputer systems that have a FORTRAN compiler and minimal graphics capabilities. This program is available for distribution to interested institutions and laboratories.     

A verifier for checking the conformance of programs with the GKS standard

A software development tool is introduced which allows to check the corrections of programs using the Graphical Kernel System (GKS). Such graphical application programs are checked whether their use of GKS functions is syntactically correct and conforms with semantic rules given by the GKS definition. Like the PFORT verifier for FORTRAN programs, this tool greatly reduces development time for GKS programs.     

GKS-the standard for computer graphics

GKS is about to be ratified as the first international standard for computer graphics. It will provide a unique base on top of which portable graphical applications software can be built. This paper traces the history of GKS and describes its main concepts.     

An introductory computer graphics laboratory

Methods are described for teaching students how to write computer programs to perform basic graphics operations. The elementary operations of scaling, translation, reflection, shear, rotation and clipping are presented. Graphics 1000, a Hewlett-Packard graphics software product is the software used. This product imbeds subroutine calls in a FORTRAN program to execute the graphics functions. The laboratory sessions are divided into modules. Module I uses interactive programs to demonstrate graphics operations. Module II introduces Graphics 1000 commands. Module III uses interactive programs to demonstrate XY plotting with as many as four graphs per plot. Module IV uses interactive programs to demonstrate rotation of objects with hidden line removal. Students are assigned tasks ranging from drawing a section of an I beam through rotation of a three-dimensional object. Computer programs used for the demonstrations are available for the students to examine in order to learn how they work.     

Algorithms for Handling the Fill Area Primitive of GKS

The fill area primitive of GKS (Graphical Kernel System)¹ is one of the more powerful features which differentiates it from earlier device independent graphics software and systems. Its specification is extremely general in the form of a closed boundary, possibly self-intersecting, and whose interior can be filled in a variety of styles. However a complete implementation of this primitive is very complex. It is difficult to find a single graphics workstation incorporating this primitive in hardware or firmware. Most GKS implementations will have to include software for simulating the appearance of this primitive on the commonly available displays and hard-copy graphics devices. Correct and efficient algorithms are necessary for developing this software. Because of the generality many of the existing algorithms are not directly applicable. In this paper we describe:
1. a new algorithm for clipping a fill area polygon, using what we have named as the Bridge Technique.
2. implementation of a plane sweep algorithm, by Nievergelt and Preparata,² for solid filling and hatching, particularly applicable to vector devices.
3. extension of the plane sweep algorithm for filling with any given pattern on raster as well as vector devices.
The algorithms have been designed to work for all special cases as well. In fact they have been implemented having in mind the fill area set primitive of GKS-3D extension.³ All these algorithms have been very successfully implemented in a commercially available GKS implementation, namely indoGKS.     

A practical strategy for certifying GKS implementations

The question of how to validate GKS implementations is crucial to the success of GKS as an international standard for computer graphics. This problem has been addressed by a series of certification workshops sponsored by the EEC. A basic strategy for testing GKS implementations is outlined and progress towards the development of a test suite is reported.     

A VLSI Implementation of the Graphics Standard GKS

The main advantage when using a standardized graphics system is quite obvious: the application programs become portable. Integrating such a system - and GKS (Graphical Kernel System) is the only one being standardized internationally - into VLSI (Very Large Scale Integration) chips, this graphics system may become an integral part of graphical devices. This guarantees a uniform interface of such devices to GKS applications. Devices of many different kinds will become compatible not only with respect to plugging but even in their logical behaviour, eliminating all device dependencies from the host software.
We have started to design the GKS-chip which will be able to be used in a great variety of devices (vector and raster type). The GKS-chip will bring the computational power to support real time picture updates, limited only by the maximally attainable output data rate.     

UGRAF3: A graphic system for process and modelling

The development and fabrication of VLSI circuits calls for permanent advances in the design and technology of these devices. Here important parameters are collected by process and device modelling. The incoming data are processed with the help of computer graphics. The GKS3D implementation UGRAF3, its application, and the relations to the international standardization process are described.     

The Specification and Implementation of GKS Application Software in ADA (R)

One of the most important uses of (interactive) computer graphics is as one of the tools available to a User Interface Management System (UIMS) for a variety of user-computer environments (UCE). Typical UCEs in vogue are Programming Support Environments (PSE), Expert System Builders (ESB), Office Automation systems (OAS). This paper concentrates on the conceptual relationship that exists between the users on the one hand and computer systems on the other. Such relationships are to be seen in the context of specific application domains. The two standards, GKS and Ada, are chosen to be the background against which the argument for a Software Methodology based on the Abstract Data Type approach, is presented. This has significant implications for a GKS binding to Ada and the development of GKS application software written in Ada. A collection of colour models is considered in detail.
Ada(R) is a registered trademark of the U.S. Government, Ada Joint Program Office.     

On developing a GKS driver architecture for raster workstations

The use of raster graphics devices needs adapting to graphics applications. The first graphics standard, the Graphics Kernel System GKS, defines a logical interface on an application and device independent level. The workstation driver maps the logical GKS functions to device functions. First some special raster device facilities are outlined and then it is shown how to use them within the driver. To reduce the amount of driver implementations a common driver concept is sought here, especially for raster devices.     

Better Understanding through Formal Specification

The Graphical Kernel System (GKS) is now registered as an ISO International Standard for computer graphics programming. One of the major innovations of the Standard is the bundled specification of aspects, a mechanism which gives the applications programmer the ability to tailor the appearance of a picture independently on each of the workstations on which it is displayed, using the capabilities of the workstations. GKS also incorporates the traditional method of individual specification of aspects in which each workstation does the best it can to represent global aspect values. In this paper a formal specification technique, the Vienna Development Method (VDM), is used to describe aspect specification. The GKS model of aspect specification is progressively constructed from simpler models. Properties of these simpler models are formulated and the specifications are proved to conform to these. The properties are then traced through the more complex models. The paper demonstrates the applicability of formal specification to the design of graphics software and the ability of formal techniques to catalyse the deeper understanding of designs.     

Computer program for determining the porous texture of solids using a modified broekhoff-de boer method

A FORTRAN 77 computer program is offered for the analysis of the porous texture of solids. The program uses a Broekhoff-de Boer method which has been e     

生物大分子图形软件的研制

我们设计了生物大分子图形显示软件（ＢＩＯＭＯＬ）．程序用ＦＯＲＴＲＡＮ７７语言编写，分为在ＶＡＸ计算机和ＳＧＩ图形工作站上运行的两个版本，该系统具有结构显示、几何操作、部分结构显示以及多模型显示等功能．     

Standards in computer graphics

GKS, which recently became the International Standards Organization (ISO) standard for computer graphics programming, is the first of a set of interlocking graphics standards. This paper outlines the important ideas behind GKS, describes its relationship with other standards and discusses the benefits of standardization.