EG1986 Proceedings (Technical Papers)

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An Adaptive Graphics Interface for Effective Visual Representation
(The Eurographics Association, 1986) Holynski, Marek; Garneau, Robert; Lewis, Elaine; A.A.G. Requicha
This paper presents a progression of experimental work aimed at incorporating principles of graphic presentation and preferences of users into a computer graphics system. These standard-s for effective visual representation of data are based on empirically developed criteria. Several different approaches for obtaining these criteria from picture attributes are described. First, relevant attributes are verified using a series of pictures created with a menu-driven program. Then representation criteria are developed by an automatic rule acquisition program in the form of condition-action rules. These rules can be utilized by an adaptive graphics system that can generate, change and refine images interactively. Practical applications are suggested.
An Advanced Display System With Natural Interactivity
(The Eurographics Association, 1986) Kankaanp, Arto; A.A.G. Requicha
This paper describes an experimental display system that allows easy interaction with the graphics display. The user uses a pen-like device to draw directly on the display surface. The system is based on an electroluminescent flat panel with a resistive touch-sensitive surface. A pen with a conductive tip is used for direct drawing. For evaluation the display system is connected to a powerful microcomputer having a true bit-mapped graphics capability. The prototype software consists of a word processing program that includes integrated line graphics drawing capability. Text correction and formatting is done directly on the display using standard proof correction marks. Graphics drawing is done by sketching a figure on the screen with the pen and correcting it by software. The system is also evaluated using the Keystroke-Level Model by CARD et. al. [1] for accomplishing the basic editing tasks with a word processing application.
Colour Section
(The Eurographics Association, 1986) -; A.A.G. Requicha
Colour Section
A consistent algorithm to fill triangles and triangular patches
(The Eurographics Association, 1986) Overveld, C.W.A.M. van; Lierop, M.L.P van; A.A.G. Requicha
In this paper an algorithm is described for filling triangles in 3D. Since this algorithm uses integer arithmetic only, it is not hampered by inconsistencies that normally arise due to finite machine precision. Moreover, the same algorithm is used for both curved and flat triangular patches.
CSI: A Processor for Image Synthesis
(The Eurographics Association, 1986) Charot, Francois; Rousee, Frank; A.A.G. Requicha
A high performance processor convenient for image synthesis is presented. The processor named CSI is programmable and can support either image synthesis by polygons or by ray casting. CSI consists of two 32- bits floating point processors as well as control facilities to support complex algorithm. CSI will be able to compute at a rate of 20 MFLOPS. Several processors can be arranged in a pipeline mode to perform the computation for image synthesis by polygons, or viewed as a set of co-processors connected to a bus and implementing efficiently image synthesis by ray casting algorithms.
Deformations of Sweep Objects in Solid Modelling
(The Eurographics Association, 1986) Post, Frits H.; Klok, Fopke; A.A.G. Requicha
Deformations, such as bending, twisting and tapering, are important operations for modifying the shape of solid objects. In this paper, we present methods to deform objects defined by sweeping. A closed 2D polygon (the contour) moves along a 3D polyline (the trajectory), thus producing a polygonal approximation of a generalized cylinder. During sweeping, the contour can be incrementally scaled and rotated, resulting in tapered and twisted objects. Also, smoothly bent objects can be produced by performing local rounding operations on trajectories. The methods have been implemented in the solid modeller PLAMO, in which the deformed sweep objects can be used, as well as other types of bodies, as primitives in a CSG tree.
Digital Synthesis Of Calligraphic Script
(The Eurographics Association, 1986) Dooijes, E.H.; A.A.G. Requicha
We discuss some of the problems associated with the generation of publication quality, quasi-calligraphic script from keyboard input. Our ultimate goal is the construction of a system for the production of Arabic texts, to be implemented on a microcomputer.
A General Purpose User Interface With Hierarchical Data Structure Management
(The Eurographics Association, 1986) Janni, Alberto Di; Italiano, Margherita; A.A.G. Requicha
This paper presents a general purpose User Interface Management System based upon a user driven menu handling and a hierarchical organization of graphic data structure. The package has mainly two purposes: one being to provide facilities to the application programmer in order to ease their tasks and the other one bei to provide a uniform enviroment to the final user. It fulfills two different tasks: it realizes the dialogue with the user and offers a complete set of high level procedures to manage graphic data. lauded attributes, like device independence, feedback at both syntactic and semantic levels, internal automatic recovery, style independent interface toward the application, management and hierarchical definition of structured graphic output, high level graphic functions and a simple definition language. Moreover this system is particularly intended to cover requirements of tools dedicated to integrated circuit design and makes use of a few devices to cut off the computation time and to optimize the memory occupation.
Geometric Boundary Modelling without Topological Data Structures
(The Eurographics Association, 1986) Takala, Tapio; A.A.G. Requicha
The Boundary Representation (BR) scheme for solid modelling is reconsidered and generalized in the paper. It is pointed out that the topological data, though usually represented separately, is derivable from the geometric data, and that there are fundamental inconsistencies between these two. The topological data structures are unnecessary or even harmful in practice as they restrict the modelling domain. New BR methodology without explicit topology is demonstrated by algorithms, which manipulate a stream of separate polygons as a solid model.
An Implementation of the GKS-3D/Phigs Viewing Pipeline
(The Eurographics Association, 1986) Singleton, Karen; A.A.G. Requicha
Following the establishment of GKS as the first international standard for computer graphics, two new standards, GKS-3D and PHIGS, are emerging which cater for three dimensional graphics. In order to display a 3-D object, a description of how it is to be viewed must be given. GKS-3D and PHIGS provide a viewing pipeline to generate the parallel or perspective view required. This paper describes in detail the functionality and an implementation of the GKS-3D/PHIGS viewing pipeline.
The Integrated Display Controller (IDC) for VLSI-Design Workstations
(The Eurographics Association, 1986) Strk, Jrgen; A.A.G. Requicha
A display controller to accelerate the updating of the frame buffer in raster displays is presented. The advantage of a frame buffer system is the ability to display pictures of any complexity, flicker free. The disadvantage is the great amount of pixel data, which must be updated, when the picture is changed. The Integrated Display Controller (IDC) described in this paper gets its name from the fact, that both a pixel plane and a processor are integrated on a single chip. An internal logical unit, a shifter and special memory are provided to process complete rows and columns of pixels, or some part of them in parallel All operations are performed in one bus cycle, which means that all the pixels addressed in the row or column are modified at the same time. Due to the special organization of the IDC, time consuming operations like block transfer or scrolling can be done significantly faster than in conventional systems. An experimental IDC with a lower screen resolution is developed to demonstrate the feasibility of the design. It is intended for use in VLSI-design workstations, where a great quantity of data has to be manipulated.
The Integration of Particle and Polygon Rendering using an A-buffer Algorithm
(The Eurographics Association, 1986) N.Magnenat-Thalmann,; D.Thalmann,; S.Beland,; A.A.G. Requicha
A particle system, as defined by Reeves, is a collection of particles that together represent a fuzzy object. Over a period of time, particles in the system are born, move, change and die. We have introduced interactive control of procedural models into our extensible director-oriented animation system MIRANIM. With this approach, a user may define his/her own evolution laws in particle systems. Systems may be initialized by interactive commands and are then updated by animation blocks, and the laws may return any state variables. Unlike Reeves' work, particle systems may intersect with other surface-based modeling primitives. Our rendering method is based on a scanline A-buffer algorithm, which is an extension of the processing of translucent polygons. This approach proved to be particularly useful for modelling objects destroyed by a fire with the presence of a wind.
An Introduction to the Graphics Systems Processor
(The Eurographics Association, 1986) Short, Graham; A.A.G. Requicha
This paper describes the system applications of the Graphics System Processor (GSP) produced by Texas Instruments Inc. The paper discusses the general-purpose capabilities of the GSP which make it a flexible processor to use. It then goes on to show how the graphics-specific parts of the GSP make it a powerful tool, ideally suited to graphics applications. Finally the paper discusses some of the programmable hardware functions of the GSP which make it easy to design into any graphics system.
Linked Management Graphics For Production Control
(The Eurographics Association, 1986) Woodgate, H. Sam; A.A.G. Requicha
This paper describes the use of Linked Graphical Displays as a means of extending the information transfer capability of Management Graphics Systems in the context of Engineering Manufacturing. As the pace and complexity of manufacturing increases, management need faster and better methods of absorbing the information contained in the large Databases used to control production. In the system described a number of different graphical displays are created from the same large Database and accessed via a "Choice Processor" to give multiple views on the situation represented by that data. The simple effectiveness of computer produced graphics as a man/machine communication media is retained but the multiple access facility enables more complex issues to be revealed and cross checked by sequentially viewing and comparing different interpretation of Data. Examples of the Charting Techniques employed are described together with an explanation of how they are created and used.
Mappings Between Product Data Definitions
(The Eurographics Association, 1986) Richter, Dieter; A.A.G. Requicha
It can be observed that existing product data interfaces are constructed by a pragmatic manner. It is not seen any theoretical approach neither for describing nor for evaluating models. In this paper an algebraic approach based on heterogeneous algebras is presented.
Memory Organization for a Cubic Frame Buffer
(The Eurographics Association, 1986) Kaufman, Arie; A.A.G. Requicha
A special memory organization of a cubic voxel-based frame buffer is presented. The memory of voxels is divided into n modules of voxels each. The k-th module groups together all the principal diagonal planes within the cubic frame buffer, that their sequential index is k mod (n ). This organization guarantees that all the n voxels which constitute a row in any direction parallel to the axes reside in different modules, permitting the retrieval of all the voxels of a row simultaneously. This memory layout is the heart of a voxel-based CUBE Architecture for three-dimensional graphics. The architecture employs three processors which access the memory, to input, manipulate, and view the image within the memory. The unique memory organization enables these processors and the entire system to cope with real-time constraints.
Methods for Cross-Sectional Design of B-Spline Surfaces
(The Eurographics Association, 1986) Woodward, Charles D.; A.A.G. Requicha
The complexity of free-form surface construction and interaction can often be reduced with methods of crosssectional design. A number of such methods, includin sweeps, skinning and surface interpolation are described in this paper for the B-spline surfaces. The methods are demonstrated with examples using the CUBES subroutine package.
Multi-Dimensional Graphics: Algorithms & Applications
(The Eurographics Association, 1986) Inselberg, Alfred; A.A.G. Requicha
A Multiple Application Graphics Integrated Circuit - MAGIC
(The Eurographics Association, 1986) Agate, M.; Finch, H.R.; Garel, A.A.; Grimsdale, R.L.; Simmonds, A.C.; Lister, P. F.; A.A.G. Requicha
MAGIC is a geometry processor which Corms a part of a graphics system based on parallel processing. The number of MAGIC processors required is dictated by the desired system performance. Each unit is capable of controlling the transformation of points and edges from the co-ordinate system of the world model into screen co-ordinates, and performing the associated clipping operations. The proposed VLSI implementation of these transformations is intended to be sufficiently flexible for additional operations such as texture mapping and ray tracing to be supported.
A Multiprocessor Architecture For High-Quality Interactive Displays
(The Eurographics Association, 1986) Sutherland, Robert J.; A.A.G. Requicha
A multiprocessor array coupled to a deep framebuffer is proposed as the basis for an interactive user environment of high quality. Several aspects of such an architecture are considered, improvements on previous approaches are suggested, and two designs of high-performance displays based on standard LSI components are described.

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