An image processing approach to computer graphics

Computer graphics was conceived as, and remains for the most part, a line-drawing phenomenon. The cautious management of display lists or of in-line vector generators has captured most of the attention of researchers in computer graphics. Cathode ray tubes with randomly positionable beams have served as the primary medium for this research and development.The underlying position of this paper is that the future of computer graphics does not lie in ‘vectored’ displays but in raster scan television, conceivably as we know it in our homes. This posture is motivated by arguments of cost and compatibility, but the most salient motivation comes in view of the ubiquitous nature of raster scan display technologies.This paper explains a way to implement an image processing approach to computer graphics, one that is conceptually straightforward and, in terms of hardware, fairly easy to design. A device is being built that encompases as much as is known about raster scan, multi-bit per point displays. The work described is conducted, principally, to produce a multi-bit per point graphics output device that dynamically shares its image storage with the memory space of an expanded mini-computer.     

A formalization for the specification and systematic generation of computer graphics systems

A formalization of graphical processes in computer graphics systems is presented in terms of functions and their system of axioms. The concept of the viewing pipeline is formalized as operation sequence which is a sequential composition of graphical elementary operations. The formalization includes two kinds of operation sequences which are used as the formal specifications of graphics systems and display devices. In order to generate a graphics system using a display device, we introduced the concept of functionality-preserving transformation of operation sequences in terms of various types of commutations among primitive operations. A type of transformation, which is called extraction, plays a central role in the generation algorithm.     

An approach to formal specification and verification of map-centered applications

Users in the domain of map-centered applications who want to specify a new application rely only on informal languages such as English. There is also no standardized terminology, resulting in ambiguous specifications. This work proposes an approach to specify and verify map-centered applications. This domain has been studied under different perspectives but there is a lack of research from the software engineering viewpoint. We characterize the domain by presenting a classification of different space models that appear in the Geographical Information Systems (GIS) literature, as well as of some of the problems addressed by map-centered applications. The proposed solution includes a language with semantics based in a formalization of each space model. This helps in verifying properties over a specification written using the formal language.     

An approach to formal verification of human–computer interaction

The correct functioning of interactive computer systems depends on both the faultless operation of the device and correct human actions. In this paper, we focus on system malfunctions due to human actions. We present abstract principles that generate cognitively plausible human behaviour. These principles are then formalised in a higher-order logic as a generic, and so retargetable, cognitive architecture, based on results from cognitive psychology. We instantiate the generic cognitive architecture to obtain specific user models. These are then used in a series of case studies on the formal verification of simple interactive systems. By doing this, we demonstrate that our verification methodology can detect a variety of realistic, potentially erroneous actions, which emerge from the combination of a poorly designed device and cognitively plausible human behaviour.     

An interactive computer graphics approach to the design of marching band routines

The availability of inexpensive minicomputers and low cost digital/analog conversion equipment enables one to use interactive graphics in situations where such techniques were previously infeasible. The University of Tulsa is presently developing an interactive graphics package entitled BANDMARCH to assist the choreography of marching band drills. The graphics hardward consist of a 32K Interdata Model 70 minicomputer, a 5MB Diablo Disc system, a Tektronix 603 monitor with 256 × 256 point display provided by a pair of Detel 8 bit D/A converters. The program enables a band director who is most likely not computer oriented to prepare a routine in an existing language (About Face, Left Flank) and view the result of his ‘design’ in real time. The obvious interactive features of editing, cataloguing and accessing standard functions must be provided in a way that can be easily understood.

T.U.'s BANDMARCH (not an acromym) provides such features. Common data structures in a relatively novel environment are a demonstration of the soundness of these techniques to an interactive graphics situation.     

An introduction to computer graphics

This paper presents a brief introduction to computer graphics. It provides an extensive bibliography of over 500 entries to assist anyone requiring a list of further reading on the subject.     

A new computer graphics approach to parameter space design of control systems

This paper presents a new approach to parameter space design of linear multivariable control systems. The complete solution of a pole region assignment problem for single-input systems is obtained as an admissible region in then-dimensional parameter space of state feedback gains. We develop a new modeling technique for these admissible parameter space regions which is superior to previous ones because it permits unambiguous and efficient graphical display of slices in 2D and 3D subspaces. In an interactive computer graphics implementation, this method provides an environment where the influence of stability, performance, robustness, integrity, and control constraints on design parameters can be directly visualized and complex tradeoffs are resolved in an interactive way. By judicious combination of overlays, color, and/ or animation, admissible ranges of up to five or six design parameters can be displayed simultaneously. A sequential decomposition technique which selects slices for full parameter space design of lower dimensional subsystems such that the remaining eigenvalues are invariant is used for systems of arbitrarily high order. Parameter space design of unity rank feedback for multiinput systems is done in exactly the same fashion, while systematic sequential design of full rank feedback is achieved as the sum of dyadic stages to which the single-input modeling techniques apply. Examples are given for all presented methods to show the flexibility and potential as a computer-aided control system design framework with a novel integration of computer graphics technology.     

The EEC workshop on formal specification of graphics software standards

This article is a report of the EEC Workshop on the Formal Specification of Graphics Software Standards, held in June 1982. The need for formal specification of graphics software is first examined, then two possible approaches, the programming language approach and the systems approach, are examined. The implications for the certification process are also examined.     

A formal approach to the specification and the behavior validation of real-time systems based on rewriting logic

Design of real time and concurrent systems requires formal approaches in order to facilitate verification and validation at each step. Methods based on formal logic have been previously suggested but they often work only in a specific domain and are generally only possible with specialized users. In an attempt to overcome these two restrictions, this paper proposes a method based on rewriting logic. A grounding in theory is not a prerequisite for users. The method integrates modularity and abstraction and follows the main principles of an object-oriented approach. Different tools are available: a graphical editor for the specification of the structure and the behavior of the objects, an inference engine for rule validation and a generator of prototypes.     

Toward a formal specification of menu-based systems

As software systems continue to increase in sophistication and complexity, so do the interface requirements that support the corresponding user interaction. To select the proper blend of ingredients that constitutes an adequate user interface, it is essential that the system designer have a firm understanding of the interaction process, i.e., how the selected dialogue format interacts with the user and with the underlying task software. To promote such an understanding, this paper presents a model that characterizes one particular dialogue format: menu-based interaction. This model is actually a sequence of models, hierarchically structured, in which each successive model builds on its predecessor by introducing additional characterization elements. The first model describes the minimal set of elements inherent to any menu-based interface; successive models extend this minimal set by introducing task actions, incremental history sequences, and frame-associated memory. These principal model elements enable the characterization of fundamental, menu-based operations like computational and decision processes, user response reversal, and user directed movement. Moreover, because the principal model elements correspond directly to “real world” objects, an intuitive as well as formal understanding of menu-based interaction can be achieved. Effectively, the model elements and the hierarchical structure imposed by these elements provide an ideal environment for characterizing and classifying menu-based systems at various levels of sophistication.     

A formal approach to the specification and transformation of constraints in MDE

This paper introduces a formal approach to constraint-aware model transformation which supports specifying constraints in the definition of transformation rules. These constraints are used to control which structure to create in the target model and which constraints to add to the created structure. The proposed approach is classified under heterogeneous, graph-based and out-place model transformations; and illustrated by applying it to a language translation. It is based on the Diagram Predicate Framework which provides a formalisation of (meta)modelling based on category theory and graph transformation. In particular, the proposed approach uses non-deleting transformation rules that are specified by a joined modelling language which is defined by relating the source and target languages. The relation between source and target languages is formalised by morphisms from their corresponding modelling formalisms into a joined modelling formalism. Furthermore, the application of transformation rules is formalised as a pushout construction and the final target model is obtained by a pullback construction.     

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.     

Object-oriented specification and formal verification of real-time systems

An object-oriented approach for specification and verification of real-time systems is described in this paper. It is motivated by taking advantage of object-oriented techniques to produce real-time software that is easy to understand, maintain, and reuse. The approach specifies the structural, behavioral, and control aspects of objects in one model with a textual representation as well as a graphical representation. For ease to comprehend and use, the model encapsulates object states and allows an analyst to focus on specifying object operations one at a time. System behavior from individual objects can be deduced and analyzed. For safety considerations, the approach supports specification of failures to object behavior and their resultant faults. The approach also supports modeling of timed temporal constraints for specifying and verifying desirable real-time properties. An object timed temporal logic OTTL is defined for expressing the syntax and semantics of these constraints. Decision procedures for their verification are also presented.     

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.