Showing papers in "Computers & Graphics in 1990"

TL;DR: Five hypotheses, focused on the types of drawings, their necessity in mechanical problem solving, and their relation to the external representation medium, are presented and supported.

TL;DR: This paper points out the semantic ambiguities of simplistic feature-based commands for editing models, and shows how space decomposition techniques and CSG expressions based on active zones reduce the cost of executing an editing command.

TL;DR: A new methodology for coupling design and automatic process planning based on form features is described that offers a balance between the computer-aided design and manufacturing planning processes based on an object-oriented, feature-based design environment and feature refinement, a new knowledge-based approach to geometric reasoning in generative process planning.

TL;DR: A Hierarchical Partial-Order Graph (HPOG) is presented that not only provides the precedence relations among assembly operations but also presents the temporal and spatial parallelism for implementing distributed and cooperative assembly.

TL;DR: In this paper, a system based on geometric constraints and reasoning is proposed for enhancing the function of computers from mere tools for conventional geometric modeling, where an essential portion of design constraints is replaced by their equivalent geometrical constraints.

TL;DR: A survey of the author's work on systems analysis, control theory, cellular automata, and computer science applied to complex biological systems.

TL;DR: A number of geometric modeling techniques with deformations applied to them are discussed in attempts to combine various approaches developed so far, with the aim of achieving free-form effect.

TL;DR: An overall framework incorporating feature-based modeling, geometric reasoning, and variational geometry is proposed as a future research direction that facilitates bridging the gap between engineering design and manufacturing.

TL;DR: The features of the area code regenerations are discussed, a valuable property is derived, and an improved line clipping algorithm based on the study is proposed which is more efficient than the Sutherland-Cohn algorithm.

TL;DR: A performance study of the new and several other well-known line clipping algorithms indicates the superiority over all other examined algorithms.

TL;DR: The sliding algorithm for interactive placement of irregular shapes used in the GIZ graphic editor and a heuristical approach which uses that algorithm for fully automatic placement are described.

TL;DR: To resolve singularities in a polyhedron, it is proposed to associate to each point of intersection a certain positive or negative weight and then to consider the sum of these weights.

TL;DR: In this article, a hierarchy of shading methods that can be used to select the required cost-performance ratio for a given visualisation task is presented, and compared both visually and theoretically.

TL;DR: The helical motion σ is interpolated by rational axial motions of degree three and four ζ by interpolating one point path σ by ζ so that all point paths of σ are interpolated in the same way.

TL;DR: The chaotic behavior of multivariable Newton's method is explored and some examples illustrate that basins of attraction may be globally dominant in the multivariables case.

TL;DR: This paper develops the core of a monotonically declarative system for variations on solids using the ASCEND language to implement both equation models and the new Euler operators.

TL;DR: This research attempts to automatically derive an assembly handling part code from a solid model boundary representation by developing a rule based recognition system and implementing it in Prolog on the Vax/Unix operating system.

TL;DR: A survey will be given on the theoretical background, corresponding procedures, and examples of application concerning the design of gear or worm profiles by means of curve primitives, their motion and manipulation, and calculation of conjugate gear profiles subjected to trochoidal motion.

TL;DR: A method is developed for recursively drawing parametric curves that avoids the problem of having to choose the subdivision of the parametric interval.

TL;DR: The lighting and shading models of PHIGS + PEX are described and a comparison of the different shading methods follows, and a new shading method, the Highlight Shading, is developed.

TL;DR: In this paper, a new, revolutionary architecture for a superworkstation for graphical purposes is presented, based on the use of advanced graphics components and mainly on the heavy use of dataflow processing technology, a still unexplored field of parallel computing as far as graphics is concerned.

TL;DR: Computer graphics is used to represent the behavior of the method of secants in the complex plane, as with Newton's method, which produces fractal structures.

TL;DR: B3-splines are introduced in this paper with explicit expressions, extensions of the B-spline but overcome the latter's weakness of not passing through interpolation points for curve or surface fitting.

TL;DR: A gasket derived from prime numbers is defined uniquely and other examples of uniquely defined gaskets are given.

TL;DR: This work presents an interactive, real-time system that displays a dynamic, three-dimensional, out-the-window view of the terrain from any vehicle, and facilitates a missile/target war gaming environment.

TL;DR: A basic introduction to computer graphics rendering techniques—techniques for the generation of realistic visual images—to serve as a base from which researchers, practitioners, and students can explore those new developments.

TL;DR: In this paper, an accelerated radiosity algorithm for general complex environments, based on environment localization and the directional form-factor concept, is presented, where objects contained in each region are adjacent to each other and pose more global illumination effects to their neighbours.

TL;DR: A fast ray tracing algorithm of CSG tree using an adaptive space subdivisions approach, based on the conversion of the objects of the scene into the volumetric Sticks representation scheme, which makes it possible either to obtain very fast low-quality frontal orthographic projections, or to produce a high-quality rendering in time less than that needed by classical ray tracing.

TL;DR: Assisted-user-interfaces (AUI) is called the class of UI based on mechanisms to be embedded in an UI model, appropriate to cope with some characteristics of user input-behaviour, namely, nondeterminism, unreliably and incompleteness.