6,519 research outputs found
Freeform User Interfaces for Graphical Computing
報告番号: 甲15222 ; 学位授与年月日: 2000-03-29 ; 学位の種別: 課程博士 ; 学位の種類: 博士(工学) ; 学位記番号: 博工第4717号 ; 研究科・専攻: 工学系研究科情報工学専
3D free-form modeling with variational surfaces
We describe a free-form stroke-based modeling system where objects are primarily represented by means of
variational surfaces. Although similar systems have been described in recent years, our approach achieves both a
good performance and reduced surface leak problems by employing a coarse mesh as support for constraint
points. The prototype implements an adequate set of modeling operations, “undo” and “redo” facilities and a
clean interface capable of resolving ambiguities by means of suggestion thumbnails
Shaping the Place - A Digital Design Heuristics Tool to Support Creation of Urban Design Proposals by Non-professionals
This paper is exploring a solution to foster civic engagement in urban design projects by applying the concepts of creativity to ICT tools. We propose a framework to support interactions between non-professionals and professionals that will ease the understanding of urban design and creation of design proposals for non-trained people and, on the other hand, offer valuable propositions and inspiration to experts. This make tool should have the presented creativity affordances known as fluency, flexibility and originality during the divergent phase of the creation process. We propose to implement a 3D collage metaphor to facilitate creative expression with 3D models. An underlying technical challenge of our application is to provide an interactive 3D mesh cutting tool to help users to express their creative potential in urban design projects. We present a non-exhaustive survey of mesh segmentation and cutting methodologies and finally, first results of implementation of a cutting algorithm
Mechanical and control-oriented design of a monolithic piezoelectric microgripper using a new topological optimisation method.
International audienceThis paper presents a new method developed for the optimal design of piezoactive compliant micromechanisms. It is based on a flexible building block method, called FlexIn, which uses an evolutionary approach, to optimize a truss-like planar structure made of passive and active building blocks, made of piezoelectric material. An electromechanical approach, based on a mixed finite element formulation, is used to establish the model of the active piezoelectric blocks. From the first design step, in addition to conventional mechanical criteria, innovative control-based metrics can be considered in the optimization procedure to fit the open-loop frequency response of the synthetized mechanisms. In particular, these criteria have been drawn here to optimize modal controllability and observability of the system, which is particularly interesting when considering control of flexible structures. Then, a planar monolithic compliant micro-actuator has been synthetized using FlexIn and prototyped. Finally, simulations and experimental tests of the FlexIn optimally synthetized device demonstrate the interests of the proposed optimization method for the design of micro-actuators, microrobots, and more generally for adaptronic structures
Utilization of Kirigami Skins as a Method of Creating Bespoke Soft Pneumatic Actuators
Soft pneumatic actuators have many applications in robotics and adaptive structures. Traditionally, these actuators have been constructed by wrapping layers of reinforcing helical fibers around an elastomeric tube. This approach is versatile and robust, but it suffers from a critical dis-advantage: cumbersome fabrication procedures. Wrapping long helical filaments around a cylindrical tube requires expensive equipment or excessive manual labor.
To address this issue, we propose a new approach towards designing and constructing pneumatic actuators by exploiting the principle of kirigami, the ancient art of paper cutting. More specifically, we use “kirigami skins”—plastic sleeves with carefully arranged slit cuts—to replace the reinforcing helical fibers.
This paper presents an initial investigation on a set of linear extension actuators featuring kirigami skins with a uniform array of cross-shaped, orthogonal cuts. When under internal pressurization, the rectangular-shaped facets defined by these cuts can rotate and induce the desired extension motion. Through extensive experiments, we analyze the elastic and plastic deformations of these kirigami skins alone under tension. The results show strongly nonlinear behaviors involving both in-plane facet rotation and out-of-plane buckling. Such a deformation pattern offers valuable insights into the actuator’s performance under pressure. Moreover, both the deformation characteristics and actuation performance are “programmable” by tailoring the cut geometry. A computational model was developed to predict the deformation pattern of the kirigami skins. This study lays down the foundation for constructing more capable Kirigami-skinned soft actuators that can achieve sophisticated motions. Additional design variables were implemented into the kirigami patterns to generate for rectangular and rhomboid elements. A kirigami skin defined by these parameters can produce a wide range of actuation patterns
Reconstruction of machine-made shapes from bitmap sketches
We propose a method of reconstructing 3D machine-made shapes from
bitmap sketches by separating an input image into individual patches and
jointly optimizing their geometry. We rely on two main observations: (1)
human observers interpret sketches of man-made shapes as a collection of
simple geometric primitives, and (2) sketch strokes often indicate occlusion
contours or sharp ridges between those primitives. Using these main observations we design a system that takes a single bitmap image of a shape, estimates image depth and segmentation into primitives with neural networks,
then fits primitives to the predicted depth while determining occlusion contours and aligning intersections with the input drawing via optimization.
Unlike previous work, our approach does not require additional input, annotation, or templates, and does not require retraining for a new category
of man-made shapes. Our method produces triangular meshes that display
sharp geometric features and are suitable for downstream applications, such
as editing, rendering, and shading
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An investigation on the framework of dressing virtual humans
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Realistic human models are widely used in variety of applications. Much research has been carried out on improving realism of virtual humans from various aspects, such as body shapes, hair, and facial expressions and so on. In most occasions, these virtual humans need to wear garments. However, it is time-consuming and tedious to dress a human model using current software packages [Maya2004]. Several methods for dressing virtual humans have been proposed recently [Bourguignon2001, Turquin2004, Turquin2007 and Wang2003B]. The method proposed by Bourguignon et al [Bourguignon2001] can only generate 3D garment contour instead of 3D surface. The method presented by Turquin et al. [Turquin2004, Turquin2007] could generate various kinds of garments from sketches but their garments followed the shape of the body and the side of a garment looked not convincing because of using simple linear interpolation. The method proposed by Wang et al. [Wang2003B] lacked interactivity from users, so users had very limited control on the garment shape.This thesis proposes a framework for dressing virtual humans to obtain convincing dressing results, which overcomes problems existing in previous papers mentioned above by using nonlinear interpolation, level set-based shape modification, feature constraints and so on. Human models used in this thesis are reconstructed from real human body data obtained using a body scanning system. Semantic information is then extracted from human models to assist in generation of 3 dimensional (3D) garments. The proposed framework allows users to dress virtual humans using garment patterns and sketches. The proposed dressing method is based on semantic virtual humans. A semantic human model is a human body with semantic information represented by certain of structure and body features. The semantic human body is reconstructed from body scanned data from a real human body. After segmenting the human model into six parts some key features are extracted. These key features are used as constraints for garment construction.Simple 3D garment patterns are generated using the techniques of sweep and offset. To dress a virtual human, users just choose a garment pattern, which is put on the human body at the default position with a default size automatically. Users are allowed to change simple parameters to specify some sizes of a garment by sketching the desired position on the human body.To enable users to dress virtual humans by their own design styles in an intuitive way, this thesis proposes an approach for garment generation from user-drawn sketches. Users can directly draw sketches around reconstructed human bodies and then generates 3D garments based on user-drawn strokes. Some techniques for generating 3D garments and dressing virtual humans are proposed. The specific focus of the research lies in generation of 3D geometric garments, garment shape modification, local shape modification, garment surface processing and decoration creation. A sketch-based interface has been developed allowing users to draw garment contour representing the front-view shape of a garment, and the system can generate a 3D geometric garment surface accordingly. To improve realism of a garment surface, this thesis presents three methods as follows. Firstly, the procedure of garment vertices generation takes key body features as constraints. Secondly, an optimisation algorithm is carried out after generation of garment vertices to optimise positions of garment vertices. Finally, some mesh processing schemes are applied to further process the garment surface. Then, an elaborate 3D geometric garment surface can be obtained through this series of processing. Finally, this thesis proposes some modification and editing methods. The user-drawn sketches are processed into spline curves, which allow users to modify the existing garment shape by dragging the control points into desired positions. This makes it easy for users to obtain a more satisfactory garment shape compared with the existing one. Three decoration tools including a 3D pen, a brush and an embroidery tool, are provided letting users decorate the garment surface by adding some small 3D details such as brand names, symbols and so on. The prototype of the framework is developed using Microsoft Visual Studio C++,OpenGL and GPU programming
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