Fully Free Form Deformation Features for Aesthetic and Engineering Designs

Résumé du livre

Analytic surfaces are unable to represent the free form shapes which are widely used in aesthetic and engineering designs. To overcome these limits, the various concepts proper to the form features have to be extended to free form surfaces. This work addresses such a complex problem while defining the concept of Fully Free Form Deformation Features (FFFDF) together with the associated creation and manipulation tools.Based on an analysis of the already available approaches, various new tools are first proposed to ease the manipulation of geometric models. A generic deformation engine is defined together with its associated constraints toolbox. It enables mastered manipulations of hybrid geometries possibly composed of curves, polylines, meshes and surfaces. The concept of multi-minimisations is introduced to permit the access to a wide variety of shapes verifying the same set of constraints. In order to fit the way designers/stylist work, two specific constraint lines are defined. They enable global as well as local shape modifications. A new way to insert discontinuities in free form surfaces is also proposed and the use of a shape-grammar to manipulate curves is explored.Based on this new set of possibilities, the concept of FFFDF is proposed and widely illustrated. These high level modelling entities enable mastered shape-oriented manipulations of free form surfaces through a restricted set of control parameters. They concur to the product geometric model definition which is often used as an intermediate object shared between the actors of the product lifecycle.