95 research outputs found
Digital sculpture : conceptually motivated sculptural models through the application of three-dimensional computer-aided design and additive fabrication technologies
Thesis (D. Tech.) - Central University of Technology, Free State, 200
Discretization of asymptotic line parametrizations using hyperboloid patches
Two-dimensional affine A-nets in 3-space are quadrilateral meshes that
discretize surfaces parametrized along asymptotic lines. The characterizing
property of A-nets is planarity of vertex stars, so for generic A-nets the
elementary quadrilaterals are skew. We classify the simply connected affine
A-nets that can be extended to continuously differentiable surfaces by gluing
hyperboloid surface patches into the skew quadrilaterals. The resulting
surfaces are called "hyperbolic nets" and are a novel piecewise smooth
discretization of surfaces parametrized along asymptotic lines. It turns out
that a simply connected affine A-net has to satisfy one combinatorial and one
geometric condition to be extendable - all vertices have to be of even degree
and all quadrilateral strips have to be "equi-twisted". Furthermore, if an
A-net can be extended to a hyperbolic net, then there exists a 1-parameter
family of such C^1-surfaces. It is briefly explained how the generation of
hyperbolic nets can be implemented on a computer. The article uses the
projective model of Pluecker geometry to describe A-nets and hyperboloids.Comment: 27 pages, 17 figure
ACM Transactions on Graphics
We present a computational approach for designing CurveUps, curvy shells that form from an initially flat state. They consist of small rigid tiles that are tightly held together by two pre-stretched elastic sheets attached to them. Our method allows the realization of smooth, doubly curved surfaces that can be fabricated as a flat piece. Once released, the restoring forces of the pre-stretched sheets support the object to take shape in 3D. CurveUps are structurally stable in their target configuration. The design process starts with a target surface. Our method generates a tile layout in 2D and optimizes the distribution, shape, and attachment areas of the tiles to obtain a configuration that is fabricable and in which the curved up state closely matches the target. Our approach is based on an efficient approximate model and a local optimization strategy for an otherwise intractable nonlinear optimization problem. We demonstrate the effectiveness of our approach for a wide range of shapes, all realized as physical prototypes
Computation with Curved Shapes: Towards Freeform Shape Generation in Design
Shape computations are a formal representation that specify particular aspects of the design process with reference to form. They are defined according to shape grammars, where manipulations of pictorial representations of designs are formalised by shapes and rules applied to those shapes. They have frequently been applied in architecture in order to formalise the stylistic properties of a given corpus of designs, and also to generate new designs within those styles. However, applications in more general design fields have been limited. This is largely due to the initial definitions of the shape grammar formalism which are restricted to rectilinear shapes composed of lines, planes or solids. In architecture such shapes are common but in many design fields, for example industrial design, shapes of a more freeform nature are prevalent. Accordingly, the research described in this thesis is concerned with extending the applicability of the shape grammar formalism such that it enables computation with freeform shapes.
Shape computations utilise rules in order to manipulate subshapes of a design within formal algebras. These algebras are specified according to embedding properties and have previously been defined for rectilinear shapes. In this thesis the embedding properties of freeform shapes are explored and the algebras are extended in order to formalise computations with such shapes. Based on these algebras, shape operations are specified and algorithms are introduced that enable the application of rules to shapes composed of freeform B´ezier curves. Implementation of the algorithms enables the application of shape grammars to shapes of a more freeform nature than was previously possible. Within this thesis shape grammar implementations are introduced in order to explore both theoretical issues that arise when considering computation with freeform shapes and practical issues concerning the application of shape computation as a model for design and as a mode for generating freeform shapes
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Programmable deposition of thin films of a user-defined profile with nanometer scale accuracy
An inkjet-based process for programmable deposition of thin films of a user-defined profile. Drops of a pre-cursor liquid organic material are dispensed at various locations on a substrate by a multi-jet. A superstrate is held in a roll-to-roll configuration such that a first contact of the drops is made by a front side of the superstrate thereby initiating a liquid front that spreads outward merging with the drops to form a contiguous film captured between the substrate and the superstrate. A non-equilibrium transient state of the superstrate, the contiguous film and the substrate then occurs after a duration of time. The contiguous film is then cured to crosslink it into a polymer. The superstrate is then separated from the polymer thereby leaving a polymer film on the substrate. In such a manner, non-uniform films can be formed without significant material wastage in an inexpensive manner.Board of Regents, University of Texas Syste
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