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Now showing 1 - 10 of 20
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    On the Evolution of Geometrical Reconstruction as a Core Technology to Sketch-Based Modeling
    (The Eurographics Association, 2004) Company, Pedro; Piquer, Ana; Contero, Manuel; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    In this work, the background and evolution of three-dimensional reconstruction of line drawing over the last thirty years is discussed. A new general taxonomy is proposed to describe and discuss the historical evolution of geometrical reconstruction and its challenges. The evolution of geometrical reconstruction from recovering know-how stored in engineering drawings to sketch-based modeling for helping in the first steps of conceptual design purposes, and the current challenges of geometrical reconstruction are also discussed.
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    Towards 3DModeling using Sketches and Retrieval
    (The Eurographics Association, 2004) Fonseca, Manuel J.; Ferreira, Alfredo; Jorge, Joaquim A.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    Retrieving 2D and 3D drawings by content is not an easy task. Automatic feature extraction, indexing and matching are some of the problems raised by these approaches. We have developed a generic method to classify, index and retrieve drawings using sketches, based on spatial relationships, shape geometry and high-dimensional indexing mechanisms. This approach has been applied with success to retrieving clip-art and complex technical drawings from large databases. In this paper we give a brief overview of our approach for content-based retrieval and describe two prototypes for retrieving 2D drawings. We also present a preliminary study that combines retrieval of 3D objects and expectation lists to define a new interaction paradigm based on suggestions. 3D objects are described using their face and edge graphs, which are then mapped into multidimensional descriptors through graph spectra. Preliminary results show that the combination of these two descriptors (faces and edges) provide a good novel method to describe and retrieve similar 3D objects. Finally, rather than developing a system to specify and display 3D queries and results, we integrated the retrieval system into a 3D modeling tool, through the use of expectation lists. This way, results from the query are presented as suggestions to the user, in what constitutes a new interaction paradigm, which is more flexible then present approaches.
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    From raw 3D-Sketches to exact CAD product models Concept for an assistant-system
    (The Eurographics Association, 2004) Diehl, Holger; Müller, Franz; Lindemann, Udo; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    As we try to develop new 3D-Sketching devices we come across the problem of how to transfer 3D-Sketches into exact product models to gain an integrated design system. There are some promising approaches for the retrieving of 3D-geometries out of 2D-Sketches, but nearly none supports the concretization of 3D-Sketches. We are developing an intelligent assistant that supports the designer in the task of concretization. Our higher level goal is a system that uses a cad-kernel and supports the designer from the early stages of sketching up to the modelling of exact product representations.
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    Constraint Stroke-Based Oversketching for 3D Curves.
    (The Eurographics Association, 2004) Fleisch, Timo; Rechel, Florian; Santos, Pedro; Stork, André; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    In this paper we present an extended approach for stroke oversketching. The stroke oversketching technique changes a curve by redrawing parts of it. Finding the part to replace and smoothing the transition is done automatically. Our extension to oversketching constraints the change of the curve to one single side profile leaving the other side profiles of the curve unchanged. Additionally we present the advantage of using this approach in car design following the classic four-side-view drawing approach.
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    A Two-Stage Approach for Interpreting Line Drawings of Curved Objects
    (The Eurographics Association, 2004) Varley, P. A. C.; Takahashi, Y.; Mitani, J.; Suzuki, H.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    We describe a two-stage approach for interpreting line drawings of curved objects. In the first stage, the user enters a natu-ral line drawing of a polyhedral template; this is automatically interpreted as the corresponding polyhedral object. In the second stage, the user enters freehand curves; by relating these to the template, a curved object can be constructed
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    Sketching Garments for Virtual Characters .
    (The Eurographics Association, 2004) Turquin, Emmanuel; Cani, Marie-Paule; Hughes, John F.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    We present a method for simply and interactively creating basic garments for dressing virtual characters in applications like video games. The user draws an outline of the front or back of the garment, and the system makes reasonable geometric inferences about the overall shape of the garment (ignoring constraints arising from physics and from the material of the garment). Thus both the garment s shape and the way the character is wearing it are determined at once. We use the distance from the 2D garment silhouette to the character model to infer the variations of the distance between the remainder of the garment and the character in 3D. The garment surface is generated from the silhouette and border lines and this varying distance information, thanks to a data-structure that stores the distance field to the character s body. This method is integrated in an interactive system in which the user sketches the garment over the 3D model of the character. Our results show that the system can be used to create both standard clothes (skirts, shirts) and other garments that may be worn in a variety of ways (scarves, panchos). Key words; Sketch-based interfaces, virtual garment, shape modelling.
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    Can Machines Interpret Line Drawings?
    (The Eurographics Association, 2004) Varley, P. A. C.; Suzuki, H.; Martin, R. R.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    Engineering design would be easier if a computer could interpret initial concept drawings. We outline an approach for automated interpretation of line drawings of polyhedra, and summarise what is already possible, what developments can be expected in the near future, and which areas remain problematic. We illustrate this with particular reference to our own system, RIBALD, summarising the published state of the art, and discussing recent unpublished improvements to RIBALD. In general, successful interpretation depends on two factors: the number of lines, and whether or not the drawing can be classified as a member of special shape class (e.g. an extrusion or normalon). The state-of-the-art achieves correct interpretation of extrusions of any size and most normalons of 20 30 lines, but drawings of only 10 20 lines can be problematic for unclassified objects.Despite successes, there are caseswhere the desired interpretation is obvious to a human but cannot be determined by currently-available algorithms. We give examples both of our successes and of typical caseswhere human skill cannot be replicated.
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    3D Sketching with Fully Free Form Deformation Features (d-F4) for Aesthetic Design
    (The Eurographics Association, 2004) Cheutet, V.; Catalano, C. E.; Pernot, J. P.; Falcidieno, B.; Giannini, F.; Leon, C.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    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 (d-F4), able to take into account the curve-oriented stylists way of working. Both the advantages of a free form surfaces deformation method and a feature-based approach are merged to define highlevel modelling entities allowing for a direct manipulation of surfaces through a restricted number of intuitive parameters. In addition, a d-F4 classification is proposed to permit a fast access to the desired shape according to its semantics. The proposed approach is illustrated with some examples.
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    A Sketch-Based Interface for Collaborative Design .
    (The Eurographics Association, 2004) Fan, Zhe; Chi, Ma; Kaufman, Arie; Oliveira, Manuel M.; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    We present an interface for collaborative conceptual design that combines sketch elements, direct manipulation of 3D objects and non-photorealistic rendering. Such a combination results in a simple and intuitive 2D-sketch-to- 3D modeling system suitable for novice users. It allows users potentially located in geographically distant areas to cooperate by sketching, exploring and modifying their ideas interactively, with immediate visual feedback. Our system prototype supports several modeling primitives and can be extended to handle user-defined objects. Potential applications of our system include early stages of urban and landscape design, rapid prototype of virtual environments, animation, education and recreational use.
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    Cascading Recognizers for Ambiguous Calligraphic Interaction .
    (The Eurographics Association, 2004) Pereira, João P.; Branco, Vasco A.; Jorge, Joaquim A.; Silva, Nelson F.; Cardoso, Tiago D.; Ferreira, F. Nunes; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    Throughout the last decade many approaches have been made to the problem of developing CAD systems that are usable in the early stages of product ideation. Although most of these approaches rely on some kind of drawing paradigm and on the paper-and-pencil metaphor, only a few of them deal with the ambiguity that is inherent to natural languages in general and to sketching in particular. Also the paper-and-pencil metaphor has not in most cases been fully accomplished, since many gesture-based interfaces resort to secondary buttons and modifier keys in order to make command strokes easier to differentiate from their geometry instantiating counterparts. In this paper we describe the architecture of GIDeS++, a sketch-based 3D modeling system that approaches these problems in three different ways: by dealing with ambiguity and exploring it to the user s benefit; by reducing the command set and thus minimizing the cognitive load on the user; and by cascading different types of gesture recognizers, which allows interaction to resort only to the button located on the tip of an electronic stylus.