Fully Free-Form Deformation Features (δ-F4) Incorporating Discontinuities

2004 ◽  
Author(s):  
Vincent Cheutet ◽  
Jean-Philippe Pernot ◽  
Jean-Claude Leon ◽  
Bianca Falcidieno ◽  
Franca Giannini
Keyword(s):  
Surface Deformation ◽  
Geometric Constraints ◽  
Free Form ◽  
Initial Surface ◽  
Cad Systems ◽  
Free Form Deformation ◽  
Deformation Features ◽  
Generate Surface ◽  
Prototype Software ◽  
Free Form Surfaces

To limit low-level manipulations of free-form surfaces, the concept of Fully Free Form Deformation Features (δ-F4) have been introduced. They correspond to shapes obtained by deformation of a surface area according to specified geometric constraints. In our work, we mainly focused on those features aimed at enforcing the visual effect of the so-called character lines, extensively used by designers to specify the shape of an object. Therefore, in the proposed approach, 3D lines are used to drive surface deformation over specified areas. Depending on the wished shape and reflection light effects, the insertion of character lines may generate surface tangency discontinuities. In CAD systems, such kind of discontinuities is generally created by a decomposition of the initial surface into several patches. This process can be tedious and very complex, depending on the shape of the deformation area and the desired surface continuity. Here, a method is proposed to create discontinuities on a surface, using the trimming properties of surfaces. The corresponding deformation features produce the resulting surface in a single modification step and handle simultaneously more constraints than current CAD systems. The principle of the proposed approach is based on arbitrary shaped discontinuities in the parameter domain of the surface to allow the surface exhibiting geometric discontinuities at user-prescribed points or along lines. The proposed approach is illustrated with examples obtained using our prototype software.

Shape Tuning in Fully Free-Form Deformation Features

2005 ◽  
Vol 5 (2) ◽  
pp. 95-103 ◽  
Author(s):  
J-P. Pernot ◽  
S. Guillet ◽  
J-C. Léon ◽  
B. Falcidieno ◽  
F. Giannini
Keyword(s):  
Objective Function ◽  
Optimization Problem ◽  
Surface Deformation ◽  
Deformation Energy ◽  
Free Form ◽  
System Perspective ◽  
Free Form Deformation ◽  
Deformation Features ◽  
Shape Tuning ◽  
Free Form Surfaces

In this paper, an approach for shape tuning and predictable surface deformation is proposed. It pertains to the development of Fully Free Form Deformation Features (δ‐F4) which have been proposed to avoid low-level manipulations of free form surfaces. In our approach, δ‐F4 are applied through the specification of higher level parameters and constraints such as curves and points to be interpolated by the resulting surfaces. From the system perspective, the deformation is performed through the modification of the static equilibrium of bar networks coupled to the control polyhedra of the trimmed patches composing the free form surfaces on which the δ‐F4 are defined. The equations system coming from the constraints specification is often underconstrained, the selection of one among the whole set of possible solutions requires the definition of an optimization problem where an objective function has to be minimized. In this paper we propose a formulation of this optimization problem where the objective function can be defined as a multiple combination of various local quantities related either to the geometry of the bar network (e.g., the length of a bar or the displacement of a node), or to its mechanical characteristics (e.g. the external force applied at a node or a bar deformation energy). Different types of combinations are also proposed and analyzed according to the induced shape behaviors. In this way the shape of a δ‐F4 can be controlled globally, with a unique minimization, or locally with different minimizations applied to subdomains of the surface.

Trimmed Free-Form Surfaces Submitted to Parametric Modelling

1997 ◽  
Author(s):  
Stéphane Guillet ◽  
Jean-Claude Léon
Keyword(s):  
Deformation Process ◽  
Surface Deformation ◽  
Geometric Constraints ◽  
Free Form ◽  
Parametric Modelling ◽  
Trimmed Surfaces ◽  
Anisotropic Surface ◽  
Surface Patches ◽  
Global Deformation ◽  
Free Form Surfaces

Abstract A new parametric modelling approach focusing on trimmed free-form surfaces is introduced. The surface deformation process required is controlled through geometric constraints such as deforming the surface until it becomes tangent to a pre-defined plane. Surfaces are bounded by trimming lines and use a multi-patch representation (i.e.: a B-Spline based model). The G1 continuity across the various surface patches is preserved during the deformation process. Therefore, the C0 and G1 continuities across trimmed surfaces boundaries can be correctly approximated by parametric constraints. The surface deformation process uses an analogy between the mechanical equilibrium of a rigid bar network and the control polyhedron of free-form surfaces. The bar network parameters may be set up to achieve either isotropic or anisotropic surface deformations. The surface deformation may be located into an arbitrary shaped area to produce either a local or a global deformation. Parametric modelling of trimmed free-form surfaces is subjected to non-linear geometric constraints. This problem resolution uses an optimization process which minimizes the shape changes of the surface area subjected to the parameters of the deformation process. An example illustrates the behavior of the parametric modelling process applied to two trimmed surfaces under various sets of continuity and boundary conditions.

Multiple-Points Constraints Based Deformation for Free-Form Surfaces

1999 ◽  
Author(s):  
J. M. Zheng ◽  
K. W. Chan ◽  
I. Gibson
Keyword(s):  
Surface Deformation ◽  
Single Point ◽  
Displacement Function ◽  
Surface Shape ◽  
Free Form ◽  
Surface Model ◽  
Deformation Method ◽  
Multiple Points ◽  
Free Form Surface ◽  
Free Form Surfaces

Abstract There is an increasing demand in the conceptual design for more intuitive methods for creating and modifying free-form curves and surfaces in CAD modeling systems. The methods should be based not only on the change of the mathematical parameters but also on the user’s specified constraints and shapes. This paper presents a new surface representation model for free-form surface deformation representation. The model is a combination of two functions: a displacement function and a function for representing an existing NURBS surface called parent surface. Based on the surface model, the authors develop two deformation methods which are named SingleDef (Single-point constraint based deformation method), and MultiDef (Multiple-points constraints based deformation method). The techniques for free-form surface deformation allow conceptual designer to modify a parent surface by directly applying point constraints to the parent surface. The deformation methods are implemented and taken in an experimental CAD system. The results show that the designer can easily and intuitively control the surface shape.

scholarly journals 3D sketching for aesthetic design using fully free-form deformation features

2005 ◽  
Vol 29 (6) ◽  
pp. 916-930 ◽  
Author(s):  
V. Cheutet ◽  
C.E. Catalano ◽  
J.P. Pernot ◽  
B. Falcidieno ◽  
F. Giannini ◽  
...  
Keyword(s):  
Free Form ◽  
Aesthetic Design ◽  
Free Form Deformation ◽  
Deformation Features

Fully free-form deformation features for aesthetic shape design

2005 ◽  
Vol 16 (2) ◽  
pp. 115-133 ◽  
Author(s):  
Jean-philippe Pernot ◽  
Bianca Falcidieno ◽  
Franca Giannini ◽  
Jean-claude Léon
Keyword(s):  
Free Form ◽  
Shape Design ◽  
Free Form Deformation ◽  
Deformation Features

A Hybrid Models Deformation Tool for Free-Form Shapes Manipulation

2008 ◽  
Author(s):  
J.-P. Pernot ◽  
B. Falcidieno ◽  
F. Giannini ◽  
J.-C. Le´on
Keyword(s):  
Geometric Constraints ◽  
Free Form ◽  
Geometric Models ◽  
Nurbs Curves ◽  
Characteristic Points ◽  
Deformation Behaviors ◽  
Geometric Representations ◽  
Different Dimensions ◽  
Simple Deformation ◽  
Prototype Software

This paper addresses the way models mixing various types of geometric representations (e.g. NURBS curves and patches, polylines, meshes), potentially immersed in spaces of different dimensions (e.g. NURBS patch and its 2D trimming lines), can be deformed simultaneously. The application domains range from the simple deformation of a set of NURBS curves in a 2D sketcher to the simultaneous deformation of meshes, patches as well as trimming lines lying in parametric spaces. The deformation itself results from the solution of an optimization problem defined by a set of geometric constraints and deformation behaviors. This new breakthrough on how geometric models can be manipulated has been made possible thanks to our linear mechanical model of deformation that can be coupled to manifolds of dimension zero (e.g. points, vertices) and one (e.g. edges, segments) whatever the spaces dimension. An extended constraints toolbox is also proposed that enables the specification of both characteristic points/curves and continuity conditions between the various geometric models. The link between the semantics of the deformation behaviors and the geometric models is ensured through the use of multiple minimizations. The approach is illustrated with several examples coming from our prototype software.

Virtual Reality Sculpture Using Free-Form Surface Deformation

1997 ◽  
Author(s):  
Todd J. Furlong
Keyword(s):  
Virtual Reality ◽  
Surface Deformation ◽  
Direct Interaction ◽  
Free Form ◽  
State University ◽  
Iowa State University ◽  
Free Form Deformation ◽  
Free Form Surface ◽  
Modes Of Interaction ◽  
Intuitive Manner

Abstract Free-form deformation allows a user to deform surfaces in an intuitive manner that has been compared to sculpting clay (Sederberg and Parry, 1986). This research investigates the use of this deformation technique to create virtual sculpture in the Iowa State University C2, a CAVE™-like apparatus. Emphasis is on intuitive and direct interaction with a surface in order to mold it into whatever shape the user has in mind. An icon-based menu is provided for changing modes of interaction, and a 3D paint tool allows users to add color to their models. Possible applications of this research include virtual art and conceptual or industrial design.

Data Reduction for Reverse Engineering of Free Form Surfaces

1999 ◽  
Author(s):  
Abbas Vafaeesefat ◽  
Hoda A. ElMaraghy
Keyword(s):  
Reverse Engineering ◽  
Data Reduction ◽  
Laser Scanner ◽  
Kriging Interpolation ◽  
Free Form ◽  
Initial Surface ◽  
Cloud Data ◽  
Short Period ◽  
Data Points ◽  
Free Form Surfaces

Abstract The large amount of irregular and unstructured data collected by the laser scanner, often refered to as “cloud data”, presents a serious challenge in reverse engineering applications. Data reduction is essential for simplifying the process of creating surface models in order to remove redundancy, save space, and speed up the display and recognition tasks. In this paper, an algorithm which effectively reduces the data collected by laser scanners is presented. Data points are first organized into a large regular grid of data points which is then interpolated using the linear polynominal dual Kriging technique to form the initial surface. Next, the algorithm generates a subset of this grid (within the specified deviation) by identifying the knots that play important role in the Kriging interpolation. Finally, additional reduction is done by merging the rectangles of the grid where the tangent variation between two rectangles is insignificant. Since the final surface is usually represented by a set of connected rectangles, the surface segmentation and fitting procedures can be accomplished in a short period of time. Examples are used to show the efficiency and validity of the proposed algorithms.

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