Interactive Graphics Applications Research Articles

Customized systems for engineering applications

An APL™-based high-productivity software-development environment is shown to enable small teams of two or three persons to build complex engineering software systems. The productivity and flexibility of such small teams, equipped with this environment, enables them to build customized engineering application systems economically. These customized systems are far more useful for the particular applications they address than are the generic systems that are commonly produced by large software-development groups. A customized engineering application system is described, illustrating the productivity of the two APL2-based computer-aided software engineering (CASE) tools used for its implementation and long-term software maintenance. The system is presented in some detail, to demonstrate its sophistication and thus provide a measure of the productivity of the software-development environment. The two CASE tools that comprise this software-development environment are used to build interactive graphical application systems, and to build systems for applications that require or can benefit from distributed cooperative processing. A list of some customized application systems built using the described environment is provided, along with estimates of the implementation efforts. The features of APL2 that play a key role in the effectiveness of these tools are also discussed.

New views and visions on product structures

Abstract The paper deals with different viewpoints in product structuring knowledge. Special interest is paid to a new viewpoint called control structure. The necessity for such a concept is based on the penetration of product oriented manufacturing systems (factories, workshops and cells) together with the related distribution of production management decision making. Control structure is an aggregated control oriented viewpoint on the product structure hiding the details of the work operations and materials requirements at the lower levels of decision making. Thus control structures are also intended for the integration and loosely coupled co-ordination of control units. The paper also strongly advocates the application of interactive graphics in the manipulation of product structure information. A practical system developed is demonstrated as a vehicle for implementing the concepts introduced.

Applications of interactive computer graphics in analyses of biomolecular structures

Applications of interactive computer graphics in analyses of biomolecular structures

On programming an interactive graphical application in logic

A hierarchical graphical modelling system and a dialogue control mechanism were designed and implemented in first order predicate logic, since logic is no longer only a way to understand problems but also a helpful tool from present technologies to solve them. Some main concepts are introduced in this paper by analyzing a given application: a flat drawing design where the user is able to graphically specify the intended configuration and get important information about the existing restrictions.

Crystallographic modelling.

The project on crystallographic modelling aims at extending the application of interactive graphics to inorganic structures. Starting from the available expertise in organic and protein modelling, the symmetry of the crystal structure is used not only to draw fixed models of many unit cells of the structure, which as an entity can be interactively manipulated, but also to change details of the structures interactively with retention of the original symmetry. Real-time shifts of atom positions are automatically applied to all symmetry-equivalent atoms given the symmetry constraints. This also applies to translations and rotations of groups of atoms. In order to get feedback about these structural changes one can simulate powder diffraction patterns in real-time mode and compare them with the experimental powder patterns. These features are crucial in truly crystallographic modelling, but have not been implemented before in other programs. The program can be used in combination with standard molecular modelling programs and is also interfaced to the Inorganic Crystal Structure Database. Before describing the realization of these features on state-of-the-art hardware, we will review the expertise in molecular modelling and discuss an MS-DOS program to study inorganic crystal structures.

Macros by example in a graphical UIMS

A macro facility that allows end users to extend interactive graphical applications is presented as part of a user-interface management system (UIMS). Such macros are expressed by example; that is, the end user programs the macro in the application's generated user interface. Problems with macros-by-example in graphical applications are explored, and requirements to accommodate such a facility are defined for the UIMS dialogue model. Existing UIMS models are reviewed relative to these requirements, and the unique facilities of the MIKE (menu interaction kontrol environment) semantics-based model are presented. The implementation of the macro-by-example system is discussed, as well as the particular implementation of a multicommand UNDO facility, which is necessary when editing micros by example.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An application of interactive analysis and computer graphics in stochastic modeling

This paper will describe the application of an interactive queueing network analyzer and an interactive graphics system to the analysis of a multiple processor computer system. The application of these tools greatly increased the productivity of the modelers and resulted in insights which would have otherwise been difficult, if not impossible, to obtain. With this experience as background, we discuss how the increasing availability of computing resources, especially high resolution interactive computer graphics and sophisticated modeling packages, is likely to have a profound influence on the applied stochastic modeler.

Logical Input Devices and Interaction

AbstractThe logical input device model, as is adopted in the standardized graphics package GKS, has been an accepted basis for producing device‐independent graphics systems. However, when used in highly interactive graphical applications, the logical input device model does not provide sufficient support for a number of fundamental issues inherent to interaction. This paper reopens a discussion which questions the functionality provided by the logical input device model when brought in conjunction with interaction. In particular, the logical input device model does not support the notion of input/output symmetry.CR Categories: 1.3.4 [Computer graphics]: Graphics utilities‐ graphics packages; 1.3.6 [Computer graphics]: Methodology and techniques‐ device independence, interaction techniques

Distributed Interactive Graphics Applications in Computational Fluid Dynamics

Implementation of two distributed graphics pro grams used in computational fluid dynamics is discussed. Both programs are interactive in na ture. They run on a CRAY-2 supercomputer and use a Silicon Graphics Iris workstation as the front-end machine. The hardware and supporting software are from the Numerical Aerodynamic Simulation project The supercomputer does all numerically intensive work and the workstation, as the front-end machine, allows the user to perform real-time interactive transformations on the displayed data. The first program was written as a distributed program that computes particle traces for fluid flow solutions existing on the su percomputer. The second is an older post-pro cessing and plotting program modified to run in a distributed mode. Both programs have realized a large increase in speed over that obtained using a single machine. By using these pro grams, one can learn quickly about complex features of a three-dimensional flow field. Some color results are presented.

Image Composition via Lookup Table Manipulation

The Image Composition Language provides a convenient way for programmers of interactive graphics application programs to define how the video lookup table of a raster display system is to be loaded. ICL allows one or several images stored in the frame buffer to be combined or modified in a variety of ways. ICL treats these images as variables, and provides arithmetic, relational, and conditional operators to combine the images, scalar variables, and constants in such image composition expressions as old_image*t+new_image*(1.0-t) and ifimager>0.5thenimage - {0.5,0,0,} else image endif. Use of the Image Composition Language relieves programmers of the tedium usually associated with loading the video lookup table to do simple image composition and modification.

A parallel processor architecture for graphics arithmetic operations

Interactive 3D graphics applications require significant arithmetic processing to handle complex models, particularly if realistic rendering techniques are used. Current semiconductor technology cannot provide the necessary performance without some form of multi-processing.This paper describes a graphics processor architecture which can be configured with an arbitrary number of identical processors operating in parallel. Each of the parallel processors can be programmed identically as if it were a single processor system, substantially simplifying software development and allowing complex rendering functions to take advantage of the multiple processors. The architecture described is able to achieve extremely high performance while allowing the price/performance of the system to be optimized for a given application.Techniques are described for handling graphics command distribution, sequencing of commands which must be processed in order, parallel processing of graphics primitive picking, and handling inquiry (read-back) commands.

Computer‐assisted three‐dimensional reconstruction technology in plant cell image analysis: applications of interactive computer graphics

SUMMARYSequences of more than 100 serial thin sections were cut of entire generative cells of pollen of Brassica campestris. Using transmission electron micrographs, outlines of the cell nucleus, vacuoles and mitochondria were digitized and stored on disc using the Carl Zeiss‐Kontron Videoplan Image Analysis System. The data collected concerned the geometry of cuts and logical collection of cuts into structures, both internal and external. A data translation and surface generation system was established to transfer these data to a VAX‐751 computer to establish an interface to the Intergraph's Interactive Graphics Design System (IGDS). Definition of the surfaces is based on the translated boundaries and structural configuration, enabling three‐dimensional visualization of: (a) the wireframe model; (b) the overall model with removed hidden lines, including colour or monochrome shading; and (c) the shaded image of the internal structures with superimposed wireframe representation of the external structures.

Quantification of red cell movement in microvessels: A new application of interactive computer graphics

Quantification of red cell movement in microvessels: A new application of interactive computer graphics

Computer-assisted morphometry using video-mixed microscopic images and computer graphics.

A microcomputer system has been developed for collection and analysis of morphometric data from video images of histological sections. Microscopic fields of view are visualized on a video monitor and are overlaid with computer-generated graphics by means of a video mixer. Planimetric data are entered by drawing on a digitizing tablet while observing the drawn image superimposed on the tissue. Programs are available to calculate various geometric parameters, count objects in a field, perform descriptive statistics, and measure volume and surface area of a solid from a series of cross sections. A program for point-counting stereology presents single points for scoring within a user-defined reference area. The potential applications of interactive graphics in morphometry are discussed.

Evaluating the user interface

In the development of a new interactive graphics application, considerable effort was spent on designing a user interface which would be easy to use. When a portion of the application was completed, typical potential users were brought in to help evaluate the interface. They were given a sample task and a short introduction to the application; then their efforts to complete the task were observed and videotaped. This method of evaluating the user interface provided the development staff with quite a bit of valuable information. Changes were made, and more testing was done, including using some subjects for a second time. This paper describes how this evaluation method was used for two purposes: to point out problem areas in the interface, and to verify that changes made have improved the user interface.

Technical implications of proposed graphics standards (Panel Session)

This panel session is intended to present recent technical developments in the efforts to standardize computer graphics. Several alternative approaches to 3-D standards will be presented and contrasted. The Virtual Device Metafile will be presented, as well as a proposed binding of the GKS standard to Fortran. Presentations will be made by the following individuals: Dr. Peter Bono is the chairman of the ANSI X3H3 technical committee developing standards for Computer Graphics Programming Languages, and will present the current status of the effort to adopt 2-D GKS as an International Standard and as an American National Standard. Tom Wright will be available to respond to questions about the Programmer's Minimal Interface to Graphics (PMIG) proposal, and its current status as a new output level of the draft proposed American National Standard (dpANS) GKS. Mark Skall will present a proposed binding of GKS to the Fortran Language. Mr. Skall will also discuss progress in the field of formal specification of graphics standards and developments in the establishment of conformance/certification procedures for implementations of GKS. Theodore Reed will present the technical content of the Virtual Device Metafile (VDM) draft proposed American National Standard. Discussed will be the relationship of the VDM to GKS and to the yet to be proposed Virtual Device Interface. Specific functionality of the VDM will be discussed as will specific bindings of that functionality as a character set extension and as a binary format. David Shuey will present an overview of the Programmer's Hierarchical Interface to Graphics (PHIGS) proposal. The PHIGS proposal is intended to support hierarchical structuring of graphics data, in contrast to the Core System and GKS proposals. This type of structure addresses highly interactive graphics applications which need to modify the presentation and the relationships within graphics data. Richard Ehlers will present the attribute model of the PHIGS proposal and explore the relationship of attribute model to structured graphics data bases. Also, Mr. Ehlers will discuss the viewing and transformation implications of structured graphics data bases using examples. Gunter Enderle is a member of the West German delegation to the International Standards Organization (ISO) Working Group on Computer Graphics. Herr Enderle will be discussing ISO proposals for the extension of the GKS standard from 2-D to 3-D functionality. Several such proposals have been made, including one by DIN (the official standards making body of the German Federal Republic) and a Norwegian proposal called IDIGS. Elaine Sonderegger was a member of the ACM SIGGRAPH Graphics Standards Planning Committee, and is the ACM SIGGRAPH representative to ANSI X3H3. Ms. Sonderegger will contrast the 3-D functionality of the Core System, IDIGS, DIN proposed 3-D extensions, and PHIGS.

Algebraic grid generation

Three methods are described for transforming grids in bounded two- and three- dimensional physical domains into a uniform grid in a rectangular computational domain. The methods are based on mathematical interpolation functions and do not require the solution of differential equations or the use of complex variables. They are simply referred to as algebraic methods and are called transfinite interpolation, the multisurface method, and the two-boundary technique. The primary advantage of the methods is that they provide explicit control of physical grid shape and physical grid spacing. Secondly, they require relatively few computations. Consequently, the application of inter-active computer graphics in conjunction with the methods is advocated for rapid generation of grids. The basic mathematical structure of each method is described, and particular attention is given to surface representation, parameter variable generation, and control function generation. Physical boundary topology and grid derivative requirements are presented.

An application of interactive computer graphics for simulation of vibratory systems

Computer simulation of two vibratory systems composed of mass. spring, and dashpot el ements is described. The first system has one degree of freedom and it undergoes damped-free vibration. The second system undergoes damped-forced vibration with two degrees of freedom. The use of refresh graphics with full interaction in real time facilitates a comprehensive parametric study of the system and the programs can be used as teaching and design aids.

A multi-processor system for hidden-surface-removal

Hidden-surface algorithms have attracted many researchers interested in creating realistic images. Many algorithms have been developed for hidden-surface removal. Different forms of "coherences" are used in order to reduce the computing required to generate a realistic image without hidden surfaces. We propose a hidden-surface removal system which uses many loosely coupled processors connected in parallel. All processors execute the same code while concurrently working on different portions of the screen. The original scene is partitioned in n equal segments, where n is the number of processors. Each processor works on a specified window of the scene. This requires additional clipping operations for each processor. Also, as the screen is partitioned into many disjoint areas, any "coherence" used by the hidden-surface algorithm is lost. Thus, each processor has to reset its segment list. The above options result in more work for each processor, limiting the gain in speed expected by displaying several processors.This scheme has been simulated for different types of scenes using 2, 4, 8 and 16 processors. Our simulation study shows that for lower values of n, the clipping time is much lower than the hidden-surface-removal time for a processor. For more than 16 processors, the clipping time is comparable to, or more than, the hidden-surface-removal time. We discuss implications of the partitioning of the scene and discuss methods to improve the scheme by using a superviser to utilize all processors efficiently.The proposed system will be very useful in many interactive graphics applications requiring fast display of realistic images.

Calibration Procedures Use with the National Weather Service River Forecast System

The National Weather Service River Forecast System consists of a set of interrelated computer programs developed to provide continuous hydrologic forecasting. The catchment model is conceptual in design and generally must be calibrated for each watershed. Current calibration procedures consist of a combination of trial-and-error and automatic-parameter optimization tech-niques. Initial parameter values are determined from analyses of the hydro-meteorological data base of a catchment. Soil moisture storage components, depletion coefficients, and other appropriate parameters are adjusted based on the results of trial-and-error simulations. An automatic-parameter optimization program utilizing a direct-search technique is used to make final modifications to the parameter values. The calibration procedures and results of a case study are presented in the paper to show how the techniques are applied. Current and important future research areas, including initial parameter estimation, physically based automatic parameter optimization, interactive computer graphics applications, and estimation theory techniques such as maximum likelihood and stochastic approximations, are discussed.