TiGL - An Open Source Computational Geometry Library for Parametric Aircraft Design

This paper introduces the software TiGL: TiGL is an open source high-fidelity geometry modeler that is used in the conceptual and preliminary aircraft and helicopter design phase. It creates full three-dimensional models of aircraft from their parametric CPACS description. Due to its parametric nature, it is typically used for aircraft design analysis and optimization. First, we present the use-case and architecture of TiGL. Then, we discuss it's geometry module, which is used to generate the B-spline based surfaces of the aircraft. The backbone of TiGL is its surface generator for curve network interpolation, based on Gordon surfaces. One major part of this paper explains the mathematical foundation of Gordon surfaces on B-splines and how we achieve the required curve network compatibility. Finally, TiGL's aircraft component module is introduced, which is used to create the external and internal parts of aircraft, such as wings, flaps, fuselages, engines or structural elements

Fairing wireframes in industrial surface design

Wireframe is a modeling tool widely used in industrial geometric design. The term wireframe refers to two sets of curves, with the property that each curve from one set intersects with each curve from the other set. Akin to the mu-, v-isocurves in a tensor-product surface, the two sets of curves in a wireframe span an underlying surface. In many industrial design activities, wireframes are usually set up and adjusted by the designers before the whole surfaces are reconstructed. For adjustment, the fairness of wireframe has a direct influence on the quality of the underlying surface. Wireframe fairing is significantly different from fairing individual curves in that intersections should be preserved and kept in the same order. In this paper, we first present a technique for wireframe fairing by fixing the parameters during fairing. The limitation of fixed parameters is further released by an iterative gradient descent optimization method with step-size control. Experimental results show that our solution is efficient, and produces reasonably fairing results of the wireframes

A computer-aided conceptual ship design system incorporating expert knowledge

PhD ThesisIn today's highly competitive shipbuilding market the emphasis is on the production of acceptable design proposals within a very short timescale. A computer-aided conceptual ship design system, which utifises the latest developments in workstation technology, has been developed. It is intended to help reduce the technical and commercial risks associated with the process of tendering for newbuilding contracts. The system as a whole, uses fundamental modeffing techniques to enable areas such as dimensions generation, huilform development, layout design, powering estimation, mass estimation, motions prediction, work content estimation and cost estimation to be considered at a much greater level of detail at the concept design stage than was previously possible. This thesis describes the specification and development of those parts of the overall design system concerned with the generation of vessel dimensions and huliform and layout design. In order to improve the flexibility of the system, a so-called expert system approach has been adopted to provide the mechanism for the control of the design methodology. For this purpose, a unique expert system shell named INCODES (INtelligent COncept DEsign System) was specified and developed. The development of this shell is described in some detail. The application of the INCODES shell to the control of the logic involved in the development of design proposals for containerships is discussed, and the knowledge base developed for the generation of these design proposals is described. The knowledge base is shown to incorporate fundamental procedures for the generation of vessel dimensions and for huliform and layout design, as well as a comprehensive suite of analysis routines to assist in the verification of the design proposals. The knowledge base is also considered to be unique in its treatment of the investigation of the loading arrangements of containership design proposals. The flexibility of the procedures developed is demonstrated by their application to the generation and examination of containership design proposals which possess a range of physical and operational characteristics.British Shipbuilders Limited, Marine Design Consultants Limited

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

The use of computer-aided design techniques in dynamic graphical simulation

Imperial Users onl

AutoGraff: towards a computational understanding of graffiti writing and related art forms.

The aim of this thesis is to develop a system that generates letters and pictures with a style that is immediately recognizable as graffiti art or calligraphy. The proposed system can be used similarly to, and in tight integration with, conventional computer-aided geometric design tools and can be used to generate synthetic graffiti content for urban environments in games and in movies, and to guide robotic or fabrication systems that can materialise the output of the system with physical drawing media. The thesis is divided into two main parts. The first part describes a set of stroke primitives, building blocks that can be combined to generate different designs that resemble graffiti or calligraphy. These primitives mimic the process typically used to design graffiti letters and exploit well known principles of motor control to model the way in which an artist moves when incrementally tracing stylised letter forms. The second part demonstrates how these stroke primitives can be automatically recovered from input geometry defined in vector form, such as the digitised traces of writing made by a user, or the glyph outlines in a font. This procedure converts the input geometry into a seed that can be transformed into a variety of calligraphic and graffiti stylisations, which depend on parametric variations of the strokes