Closure of Boolean operations on geometric entities

Tilove, Robert; Requicha, Aristides A. G.

doi:10.1016/0010-4485(80)90025-1

Cited by 74 publications

(27 citation statements)

References 5 publications

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“…This hierarchical level will be used later in the animation process. Another interesting aspect of this level lies in the fact that, for one object topology, we can find many different aspects of object geometry or colours (ex: garden LGRC (Bouatouch et al 1986) is a compiled language, developed at IRISA, which gives a representation of the geometric modelling under a CSG tree form (Requicha 1980;Tilove and Requicha 1980). We can also use a polygonal representation, interactively built or derived from the CSG tree (Badouel …”

Section: Description Of Our Animation Conceptmentioning

confidence: 98%

Dynamics and unification of animation control

Arnaldi

Dumont

Hégron

1989

The Visual Computer

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We present an analysis of unified animation control processes. The design of an animation system is strongly coupled with the considered application. Most of the existing systems are specialized. For example, in audiovisual production or in C.A.D., only a few systems specialized in mechanical computation have capabilities in the image synthesis field. We are working on the design of a general animation system, including generation of motion defined by use of mechanical laws, in an audiovisual environment. Our system is built around a structured graph in which we store a hierarchical description of the objects and mechanical joints. The joints may be used to link the objects together to allow the building of multibody mechanical systems. For objects which are not submitted to mechanical laws, motion control can be specified by key-framing techniques or explicit trajectories. We use a dynamical formalism based upon the principle of virtual work associated with LAGRANGE's multipliers and that takes into account holonomic and nonholonomic constraints. The generation of the differential motion equations system is automatically built by performing symbolic derivations. These equations are then solved for each time step and give object locations and orientations.

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Section: Description Of Our Animation Conceptmentioning

confidence: 98%

Dynamics and unification of animation control

Arnaldi

Dumont

Hégron

1989

The Visual Computer

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“…However, unless these forms are explicitly defined as parts they cannot be available for manipulation, and this necessitates restructuring the shape so that the alternative parts are defined. In commercial systems, restructuring of a shape is achieved either by redefining the parts through repeated use of operations that allow lines to be cut and/or combined and parts redefined, or by applying regularised Boolean operations of intersection, union or difference [21], or by re-constructing the shape explicitly from the required parts. These options can be laborious and time-consuming, and an alternative method that enables users to efficiently and intuitively manipulate shapes according to the parts recognised by the user at any particular moment would be beneficial for supporting computer-aided shape exploration.…”

Section: Supporting Shape Exploration With Eye Trackingmentioning

confidence: 99%

Evaluating an eye tracking interface for a two-dimensional sketch editor

Jowers

Prats

McKay

et al. 2013

Computer-Aided Design

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Throughout the history of CAD, a variety of interfaces have been employed with the aim of supporting designers' construction and manipulation of digital models. This paper explores the potential of eye tracking as a CAD interface, and presents a prototype that uses collected gaze data to support shape exploration in a two-dimensional vectorbased sketch editor. The eye tracking interface uses the visual interactions of users to identify interpretations of constructed shapes, according to recognised parts identified using methods from shape grammar research. It can therefore be argued that it supports construction and manipulation of shapes according to user intent. The prototype has been evaluated in a user study where design students carried out controlled shape exploration exercises which involved interpretation and manipulation of shapes. In the paper, key concepts of eye tracking methodology are introduced; the methods used to implement the eye tracking interface are described; and the user study and its outcomes are reported. The results are positive and indicate the potential for eye tracking as an interface for supporting shape exploration in CAD. Research Highlights• Explores the potential of eye tracking as an interface for computer aided-design• Describes methods for inferring user intent with respect to digital shape manipulation, based on gaze data • Presents a prototype eye tracking interface that supports dynamic shape interpretation in a vector-based sketch editor • Reports the outcomes of a user study that evaluates how successful the eye tracking interface is at inferring users' intent with respect to shape manipulation

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“…A solution is to use CSG trees (Constructive Solid Geometry), where the leaves are volumetric primitives, while the nodes are regular operators (Tilove and Requicha, 1980) combined with a geometric transformation or a shape deformation (Barr, 1984). But CSG trees are not well adapted to manage curves, surfaces or any free-form objects, because they were initially created to manage internal composition laws defined on a set of solid objects.…”

Section: A Semantic 3d Model For Object Simulationsmentioning

confidence: 99%

Cooperation between reactive 3D objects and a multimodal X Window kernel for CAD

Bourdot

Gherbi

1998

Multimodal Human-Computer Communication

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Abstract. From the early steps of sketching to final engineering, a frequent and very important activity in designing objects is to perform graphical and spatial simulations to solve the constraints on the objects which are being designed. But when we analyse work situations involving the use of CAD systems, it is today an acknowledged fact that these tools are not helpful to perform these types of simulations. While knowledge modeling based on form feature concepts already offers some possibilities for attaching behaviour to objects, the simulation activity requires in addition a 'real time' and 'intelligent' management of the interactions between the 3D virtual objects and the CAD user.Our general purpose is to study how future CAD systems could be improved to achieve the simulation steps of object design. In this context we present some issues concerning the cooperation between a model of reactive 3D objects and a multimodal X Window kernel. We have developed a prototype of a system where objects with reactive behaviour can be built, and with which the user can interact with a combination of graphical actions and vocal commands. This prototype is used to evaluate the feasability and the usefulness of the integration of such techniques in futur applications that would be used by object designers in a real working context. We describe the current state of this system and the planned improvements.

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Closure of Boolean operations on geometric entities

Cited by 74 publications

References 5 publications

Dynamics and unification of animation control

Dynamics and unification of animation control

Evaluating an eye tracking interface for a two-dimensional sketch editor

Cooperation between reactive 3D objects and a multimodal X Window kernel for CAD

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