This paper presents a new approach to rendering triangular algebraic free form surfaces. A hierarchical subdivision of the surface with associated tight bounding volumes provides for quick identification of the surface regions likely to be hit by a ray. For each leaf of the hierarchy an approximation to the corresponding surface region is stored. The approximation is used to compute a good star...

ÐFree-Form Deformation (FFD) is a versatile and efficient modeling technique which transforms an object by warping the surrounding space. The conventional user-interface is a lattice of movable control points but this tends to be cumbersome and counterintuitive. Directly Manipulated Free-Form Deformation (DMFFD) allows the user to drag object points directly and has proven useful in an interact...

This paper describes the use of “free-form” virtual reality (VR) interactions, specifically input from sweeping 3D movements of the hands in space, within scientific visualization applications. Use of this relatively unconstrained style of input for science is often limited because it can be difficult to control, however if controlled via appropriate interaction techniques, it can also provide ...

Implicit surfaces offer many advantages for sketch-based modeling systems, such as blending, CSG, and a procedural object hierarchy. Free-form deformation (FFD) is also extremely useful in this context, however existing FFD approaches do not support implicit surface representations, and FFD lattice manipulation is time-consuming compared to sketch-based techniques. In this thesis, an FFD techni...

Lattice structures are used in the design of metamaterials to achieve unusual physical, mechanical, or biological properties. The properties of such metamaterials result from the topology of the lattice structures, which are usually three-dimensionally (3D) printed. To incorporate advanced functionalities into metamaterials, the surface of the lattice structures may need to be ornamented with f...

This paper addresses the designers’ activity and in particular the way designers express an object shape in 2D sketches through character lines. The tools currently available in commercial CAS/CAD systems to manipulate the digital models are still not sufficiently suited to support design. In this paper, we introduce the so-called Fully Free Form Deformation Features (δ-F), able to take into ac...

texture mapping, . . Image warpmg, isometries, distance preserving, developable surfaces Texture mapping is a frequently exploited technique in computer graphics aimed at the emulation of high-resolution details in surfaces. In this paper we present a distance-ratios preservation method for bivariate raster texture mapping to free-form surfaces in an arbitrarily precise manner. The proposed met...

We introduce a new surface representation for recognizing curved objects. Our approach begins by representing an object by a discrete mesh of points built from range data or from a geometric model of the object The mesh is computed from the data by deforming a standard shaped mesh, for example, an ellipsoid, until it fits the surface of the object. We define local regularity constraints that th...

We present a robust algorithm to construct an “inner” simplicial hull Σ as a single step of subdivision of an input polyhedron P in three dimensional space. Similar to traditional subdivision schemes P becomes the ‘control net’ for free-form modeling while an inner surface triangulation T of Σ is a second level mesh. Free-Form C1 cubic A-patches and C2 quintic A-patches can then be constructed ...

Programs written in point-free form express computation purely in terms of functions. Such programs are especially amenable to local transformation. In this paper, we describe a process for optimising the transport of data through point-free programs. This process systematically applies local transformations to achieve effective global optimisation. We describe the strategies we employ to ensur...