EG1989

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MICRO-UIDT: A User Interface Development Tool
(Eurographics Association, 1989) Mao, Qijing
A user interlace development tool called Micro-UIDT is described. Micro-UIDT provides an interactive design environment fur the user interface designers. The designing language for defining user interfaces are visual and nonprocedural. State transition diagrams are used as the notation for specifying man-machine dialogue control. Some extensions are added into the notation, so that the user interfaces with semantic feedback can be defined. The approach of specifying the presentation of application data is bottom-up and direct operation. The designing language for this has two major description facilities, one for describing graphics and another for describing the relationships between the graphics and the application variables. A concept of graphic object is used in the language, which can make the design result be abstracted and reused. The user interfaces developed with Micro-UIDT are small in size and fast in speed.
Message-Based Object-Oriented Interaction Modeling
(Eurographics Association, 1989) Breen, David E.; Kühn, Volker
This paper describes a message-based object-oriented tool for exploring mathematically-based interactions which produce complex motions for computer animation. The tool has been implemented as an object in the object-oriented computer animation system The Clockworks. It supports the definition of complex interactions between geometric objects through the specification of messages to the interacting objects. Our approach is general, flexible and powerful. The tool itself is not hardcoded to a particular application. It simply sends the messages specified by the user. Messages are specified as strings which may be stored, modified and interpreted. Since the tool is part of The Clockworks it may utilize many of the powerful features of the system, including data structuring, mathematical, geometric modeling, and rendering objects. The tool has been used to explore a general spring and mass model, and the response of objects in a vector field.
When is a Line a Line?
(Eurographics Association, 1989) Brodlie, Ken W.; Göbel, Martin; Roberts, Ann; Ziegler, Rolf
Conformance testing of graphics systems is a very complex and exhausting task. Years of practice with the GKS testing tools have shown a need for the automatic testing of visual output. Indeed, with regard to graphics systems which are more precisely specified than GKS like the Computer Graphics Interface (CGI), conformance testing is not manageable at all unless a major part can be automated. This paper discusses different strategies for the automatic testing of pictorial effect. It concentrates on the definition of lines and describes a strategy to answer the question put in the title by the testing system. Finally, automatic testing of simple graphical operations such as segment highlighting and visibility is discussed.
Toward Realistic Formal Specifications for Non-Trivial Graphical Objects
(Eurographics Association, 1989) Fiume, Eugene
Formal specification has long been advocated in programming methodology, and is becoming increasingly popular in computer graphics to characterise the semantics of components of graphics systems. Unfortunately, formal specifications tend to sacrifice realism for abstraction. The result is often a specification that is not as relevant to real graphics systems as it could be. This paper suggests that the use of sharper mathematical tools, together with the use of object orientation (i.e., data abstraction with inheritance) provides a way of resolving this problem. As an example, we attempt to specify formally classes of bitmaps and images. These are particularly interesting choices, for bitmaps and images are mutable, bitmaps can have a perceived effect on images, and their semantics depends on context.
Forest of Quadtrees: An Object Representation for 3D Graphics
(Eurographics Association, 1989) Kaufman, Arie; Bandopadhay, Amit
A forest of quadtrees is proposed as an alternative data structure for representing and manipulating 3D and 2.5D graphics. A data representation of a forest offers space savings over common quadtrees by concentrating the vital information and discarding unused pointers. Several properties of the forest of quadtrees and the basic operations for display and elementary transformations like rotation, reflection, enlargement, reduction, and translation are investigated. Specifically, the temporary memory requirements and duplication time of the algorithms are analyzed.
GKS, Structures and Formal Specification
(Eurographics Association, 1989) Duce, D. A.
There are now three International Standards for application program interfaces for computer graphics programming, GKS, GKS-3D and PHIGS. In this paper a simplified model GKS-like system is described and a 2D PHIGS-like system is then described in terms of this and a centralized structure store. Formal specifications of the systems are given illustrating how the specification of a system can be built up from a hierarchy of simple components. The purpose of the paper is to illustrate one approach to the description of a compatible family of graphics standards and the use of formal specification techniques in this process.
Visualisation in Astrophysics
(Eurographics Association, 1989) Ertl, T.; Geyer, F.; Herold, H.; Kraus, U.; Niemeier, R.; Nollert, H.- P.; Rebetzky, A.; Ruder, H.; Zeller, G.
This paper reports on progress we have made in modelling cosmic X-ray sources on supercomputers. The results we present are meant to serve as an example for the fact that sophisticated visualization techniques play a crucial role in scientific computing. Among the graphical methods we demonstrate, raytracing in curved space-time and a physically motivated 3D-volume rendering algorithm might be of interest to the graphics community in general.
The Structure of Tube - A Tool for Implementing Advanced User Interfaces
(Eurographics Association, 1989) Hill, Ralph D.; Herrmann, Marc
Good user interfaces are very costly to implement and maintain. As user interfaces become more advanced, moving to various forms of direct manipulation, they become even more expensive and difficult to implement. In the recent past, many user interface management systems and related tools for the rapid development of user interfaces have been developed. Some have been successful at reducing interface development costs for some styles of interface, but none fully address the requirements of advanced direct manipulation interfaces. We claim this is because they are founded on basic models and components that work only for simpler interaction styles. We present Tube, a tool for the rapid development of advanced direct manipulation user interfaces, describe its structure, and show how it differs from, and is better than, traditional structures.
Pixel Selected Ray Tracing
(Eurographics Association, 1989) Akimoto, Taka-aki; Mase, Kenji; Hashimoto, Akihiko; Suenaga, Yasuhito
This paper presents a new ray-tracing acceleration technique called Pixel Selected Ray-Tracing (PSRT). PSRT uses undersampling based on Iterative Central Point Selection(ICPS) along with checking for similarities among trees in neighboring pixels. By using ICPS and trees, the largest danger of missing object borders can be drastically reduced. Although the speed increase attributable to PSRT varies with the image generation environment, according to experiments comparing PSRT with standard ray-tracing, PSRT is 2.6 to 8.2 times faster than standard ray-tracing for 512 by 512 pixel images, maintaining the same visual image quality. It is true that images generated by this method may contain very small errors. However, such errors can be reduced and may be made visually negligible by using ICPS and the trees of ray-object intersection to check for similarities.
The Macro-Regions: An Efficient Space Subdivision Structure for Ray Tracing
(Eurographics Association, 1989) Devillers, Olivier
Ray tracing is the usual image synthesis technique which allows rendering of specular effects. The use of space subdivision for ray tracing optimization is studied. A new method of subdivision is proposed : the macro-regions. This structure allows a different treatement of the regions with a low density of information, and the regions with a high density of information. A theoretical and practical study of space subdivision methods -grid, octree- and the macro-regions structure is presented.
Adding Parallelism in Object Space to the Rendering Pipeline
(Eurographics Association, 1989) Chapman, Paul A.; Lewis, Eric
This paper analyses the problem of adding parallelism to the rendering pipeline and discusses the reasons for advocating an object-space partition. Consideration of the methods of work distribution and the rendering techniques which are desired, leads to the proposition of two algorithms for performing the partition. An architecture for their implementation is considered and evaluated.
2.5 Dimensional Graphics Systems
(Eurographics Association, 1989) Herman, Ivan
The outline of an extension of traditional 2D graphics systems is given. This extension is aimed at supporting a three dimensional application program, without incorporating full viewing into the general graphics system itself. The resulting system might be very advantageous for large application programs which have their own three dimensional facilities.
Anti-Aliasing by Successive Steps with a Z-Buffer
(Eurographics Association, 1989) Ghazanfarpour, D.; Peroche, B.
We present a method allowing to solve the three problems arising when a scene is displayed with the z-buffer algorithm. The proposed algorithm only requires one extra memory bit per pixel and delivers good quality images. It is fast because, in particular, the most expensive calculations such as antialiasing or texture mapping are made only for visible pixels of the scene.
On the Software Structure of User Interface Management Systems
(Eurographics Association, 1989) Burgstaller, Johann; Grollmann, Joachim; Kapsner, Franz
Specific systems for the development of user interfaces (Uls) are used today for coping with the increasing problems of human-computer communication. Some of those systems are based on well-defined models for humancomputer interaction. Important requirements of such systems are: consideration of standards, most notably graphics functionality and windowing functionality, openness to all interaction styles, and provision of comfortable design tools that allow UI prototyping. An evaluation of the existing systems reveals that they fulfill only some of those requirements. We present a layered model for the interface between an application's functionality and its UI, which explicitly takes care of standards. Based on this model we implement a system for efficient design and administration of Uls. An internal interface among all tools, namely, a PROLOG-like formalism used for the description of UI objects, is of central importance. This formalism makes all tools independent from the dialog objects, hence our system is truly open. The core of our system consists of a comfortable graphically interactive editor for UI design and an interpreter. The interpreter is mainly responsible for the presentation of Uls which are described according to this formalism. The output of the editor will be a description of Uls according to the formalism. Our oal is the development of a functionally complete object-oriented set of formalism-based tools; these tools will also use artificial intelligence techniques for an adaptation of Uls to user needs.
Algorithms for 2D Line Clipping
(Eurographics Association, 1989) Skala, Vaclav
New algorithms for 2D line clipping against convex, non-convex windows and windows that consist of linear edges and arcs are being presented. Algorithms were derived from the Cohen-Sutherland 's and Liang-Barsky s algorithms. The general algorithm with linear edges and arcs can be used especially for engineering drafting systems. Algorithms are easy to modify in order to deal with holes too. The presented algorithms have been verified in TURBO-PASCAL. Because of the unifying approach to the clipping problem solution all algorithms are simple, easy to understand and implement.
Representing Tolerance Information in Feature-Based Solid Modelling
(Eurographics Association, 1989) Falcidieno, Bianca; Fossati, Bruno
In this paper a system for defining dimensions and tolerances is presented which deals with the geometric representation of the objects in a coherent and compact way. This model is a combination of a hierarchical boundary model to represent geometry of the object with features and a relational graph model to encode dimensions and tolerances. In this way, the proposed model can be considered a ”product model” that, besides geometric and topological information about the feature components of a solid object, also codifies information about dimensions represented by relative positron operators connected to faces which are the primitive geometric entities of the object model. The method can automatically control the validity of the geometric and topological model of the object each tame that a new tolerance node is added to the structure or a tolerance constraint already existing is modified. In this case, it also translates changes in dimensional values into corresponding changes an geometry and topology.
Two Object-Oriented Models to Design Graphical User Interfaces
(Eurographics Association, 1989) Hübner, Wolfgang; Gomes, Mario Rui
Object-oriented concepts are well-suited to deal with the characteristics of user interfaces. Up to now several attempts to integrate the object-oriented paradigm in user interface models were evolved and led to distinctive resulting models due to different requirements of the target application area. Within this paper two independently developed object-oriented interaction models are presented which emphasize the graphical requirements to user interfaces. These are among others its hierarchical nature, dynamical topology of the user interface, strong connection between input, output and the semantics of the application and the diversity of the graphics input devices and interaction techniques. Both approaches converge in the following aspects: Instead of having separated user interface layers the components of an interactive graphics application's user interface are embedded locally within interaction objects. Therefore dialogue control, input, output and the dynamical behavior are organized as a micro-cosmos within each object. Compound interaction objects can be designed. Temporal logical operators are used to specify the dialogue. Tools to support the implementation of each model are described. By describing both approaches this paper could be a contribution toward establishing a uniform object-oriented framework for the design of graphical user interfaces.
A Topological Map-Based Kernel for Polyhedron Modelers: Algebraic Specification and Logic Prototyping
(Eurographics Association, 1989) Dufourd, Jean-Francois
This paper deals with the topology of surfaces, in the boundary representation of three dimensional objects. Orientable, not orientable, closed or open surfaces are efficiently described and handled when considered as combinatorial generalized maps. An algebra of such maps is first described. Using this algebra, operations to build polyhedra step by step are next defined. That is the basis of a graphical modeler presently under consideration. The presentation uses algebraic software specification techniques in an abstract way. Finally, a systematical validation of the specification by logic prototyping is described.
Components, Frameworks and GKS Input
(Eurographics Association, 1989) Duce, D. A.; Ten Hagen, P.J.W.; Van Liere, R.
This paper was inspired by the Components/ Frameworks approach to a Reference Model for computer graphics, currently under discussion in the ISO computer graphics subject committee. The paper shows how a formal description of the GKS input model may be given in Hoare’s CSP notation and explores some extensions in which some of the components in the GKS model are replaced by more interesting ones. The paper thus demonstrates some of the power and flexibility inherent in the Component/ Frameworks idea. The use of a formal notation led to a deepening of the authors’ understanding of the input model and suggested some different ways of looking at the input model.
A Parallel Image Computer with a Distributed Frame Buffer: System Architecture and Programming
(Eurographics Association, 1989) Potmesil, Michael; McMillan, Leonard; Hoffert, Eric M.; Inman, Jennifer F.; Farah, Robert L.; Howard, Marc
We describe the system architecture and the programming environment of the Pixel Machine - a parallel image computer for 2D and 3D image synthesis and analysis. The architecture of the computer is based on an array of asynchronous MIMD nodes with a parallel access to a large frame buffer. The system consists of a pipeline of pipe nodes which execute sequential algorithms and an array of m x n pixel nodes which execute parallel algorithms. A pixel node accesses every m-th pixel on every n-th scan line of a distributed frame buffer. Each processing node is based on a high-speed, floating-point programmable processor. The programmability of the computer allows all algorithms to be implemented in software. A set of mapping functions transfers image algorithms written for conventional single-processor computers to algorithms which execute in the pixel nodes and access the distributed frame buffer. The ability to use floating-point computations in pixel operations, such as antialiasing, ray tracing, and filtering, allows high-quality image generation and processing. The image computer provides up to 820 megaflops of peak processing power and 48 megabytes of memory for data-visualization applications.

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