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Now showing 1 - 10 of 23
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    Investigating User Requirements and Usability of Immersive Three-dimensional Sketching for Early Conceptual Design - Results from Expert Discussions and User Studies
    (The Eurographics Association, 2008) Israel, Johann Habakuk; Zöllner, Christian; Mateescu, Magda; Korkot, Rasim; Bittersmann, Gunnar; Fischer, Patrick Tobias; Neumann, Jens; Stark, Rainer; Christine Alvarado and Marie-Paule Cani
    As immersive 3-d user interfaces reach broader acceptance, their use as sketching media is attracting both commercial and academic research. So far little is known about user requirements and cognitive aspects of immersive 3-d sketching. Also its integration into the workflow of virtual product development is far from being solved. In this paper we present results from two focus group expert discussions and a comparative user study on immersive 3-d sketching which we conducted among professional furniture designers. The results of the focus groups show a strong interest in using the three-dimensional space as a medium for conceptual design. Users expect it to provide new means for the sketching process, namely spatiality, one-to-one proportions, associations, and formability. Eight groups of functions required for 3-d sketching were generated during the discussions. The results from the user study show that both the sketching process and the resulting sketches differ in the 2-d and 3-d condition, namely in terms of the perceived fluency of sketch creation, of the perceived appropriateness for the task, of the perceived stimulation by the medium, movement speed, sketch sizes, details, functional aspects, and usage time. We argue that both 2-d and 3-d sketching are relevant for early conceptual design. As progress towards 3-d sketching, new tangible interactive tools are needed which account for the user's perceptual and cognitive abilities.
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    AlgoSketch: Algorithm Sketching and Interactive Computation
    (The Eurographics Association, 2008) Li, Chuanjun; Miller, Timothy S.; Zeleznik, Robert C.; Jr., Joseph J. LaViola; Christine Alvarado and Marie-Paule Cani
    We present AlgoSketch, a pen-based algorithm sketching prototype with supporting interactive computation. AlgoSketch lets users fluidly enter and edit 2D handwritten mathematical expressions in the form of pseudocode-like descriptions to support the algorithm design and development process. By utilizing a novel 2D algorithmic description language and a pen-based interface, AlgoSketch users need not work with traditional, yet complex 1D programming languages in the early parts of algorithm development. In this paper, we present the details behind AlgoSketch including the design of our 2D algorithmic description language, support for iteration and flow of control constructs and a simple debugging trace tool. We also provide some examples of how AlgoSketch might be used in the context of image analysis and number-theoretic calculation problems found. Based on preliminary user feedback, we believe AlgoSketch has the potential to be used to design and test new algorithms before more efficient code is implemented. In addition, it can support users who may not be familiar with any advanced programming languages.
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    MathBrush: A Case Study for Pen-based Interactive Mathematics
    (The Eurographics Association, 2008) Labahn, George; Lank, Edward; Marzouk, Mirette; Bunt, Andrea; MacLean, Scott; Tausky, David; Christine Alvarado and Marie-Paule Cani
    Current generations of computer algebra systems require users to transform two dimensional math expressions into one dimensional strings, to master complex sets of commands, and to analyze lengthy output strings for relevant information. MathBrush is a system, designed based on research in education pedagogy, that provides a pen-based interface to many of the features of computer algebra systems. We describe relevant work in education pedagogy as a motivation for MathBrush's design. We highlight aspects of MathBrush that are unique from other contemporary pen-math systems. Finally, we present the results of a thinkaloud evaluation of the MathBrush system. Together, these observations validate aspects of the current design of MathBrush, suggest areas for refinement, and inform the design of future pen-math systems.
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    Sketch and Paint-based Interface for Highlight Modeling
    (The Eurographics Association, 2008) Pacanowski, Romain; Granier, Xavier; Schlick, Christophe; Poulin, Pierre; Christine Alvarado and Marie-Paule Cani
    In computer graphics, highlights capture much of the appearance of light reflection off a surface. They are generally limited to pre-defined models (e.g., Phong, Blinn) or to measured data. In this paper, we introduce new tools and a corresponding highlight model to provide computer graphics artists a more expressive approach to design highlights. For each defined light key-direction, the artist simply sketches and paints the main highlight features (shape, intensity, and color) on a plane oriented perpendicularly to the reflected direction. For other light-and- view configurations, our system smoothly blends the different user-defined highlights. Based on GPU cabilities, our solution allows real-time editing and feedback. We illustrate our approach with a wide range of highlights, with complex shapes and varying colors. This solution also demonstrates the simplicity of introduced tools.
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    Automatic Interpretation of Depiction Conventions in Sketched Diagrams
    (The Eurographics Association, 2008) Lockwood, Kate; Lovett, Andrew; Forbus, Ken; Dehghani, Morteza; Usher, Jeff; Christine Alvarado and Marie-Paule Cani
    Diagrams are used in many educational settings to convey physical and spatial information. Sketching is used, in turn, to test students' understanding of course concepts. The availability of Tablet PCs offer an exciting opportunity to create intelligent tutoring systems which automatically provide students with feedback on sketched work, and to create systems which can capture knowledge via interaction with people. However, for such systems to provide useful and relevant feedback, the software must be able to interpret diagrams that students have drawn. Interpreting diagrams correctly requires an understanding of some basic depiction conventions common in diagrammatic representation. Here we describe how to combine general semantic information about objects in sketched diagrams with geometric information from the sketch to aid in the interpretation of regions and edges. This system is implemented as an extension to the CogSketch sketch understanding system.
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    Repoussé: Automatic Inflation of 2D Artwork
    (The Eurographics Association, 2008) Joshi, Pushkar; Carr, Nathan A.; Christine Alvarado and Marie-Paule Cani
    We describe a new system for the interactive enhancement of 2D art with 3D geometry. Repoussé creates a 3D shape by inflating the surface that interpolates the input curves. By using the mean curvature stored at boundary vertices as a degree of freedom, we are able to control the inflated surface intuitively and efficiently using a single linear system. Repoussé handles both smooth and sharp position constraints. Position constraint vertices can also have curvature constraints for controlling the inflation of the local surface. We show the applications of our system in font design, stroke design, photo enhancement and freeform 3D shape design.
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    Matisse: Painting 2D regions for Modeling Free-Form Shapes
    (The Eurographics Association, 2008) Bernhardt, Adrien; Pihuit, Adeline; Cani, Marie-Paule; Barthe, Loic; Christine Alvarado and Marie-Paule Cani
    This paper presents Matisse, an interactive modeling system aimed at providing the public with a very easy way to design free-form 3D shapes. The user progressively creates a model by painting 2D regions of arbitrary topology while freely changing the view-point and zoom factor. Each region is converted into a 3D shape, using a variant of implicit modeling that fits convolution surfaces to regions with no need of any optimization step. We use intuitive, automatic ways of inferring the thickness and position in depth of each implicit primitive, enabling the user to concentrate only on shape design. When he or she paints partly on top of an existing primitive, the shapes are blended in a local region around the intersection, avoiding some of the well known unwanted blending artifacts of implicit surfaces. The locality of the blend depends on the size of smallest feature, enabling the user to enhance large, smooth primitives with smaller details without blurring the latter away. As the results show, our system enables any unprepared user to create 3D geometry in a very intuitive way.
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    Supporting Reinterpretation in Computer-Aided Conceptual Design
    (The Eurographics Association, 2008) Jowers, Iestyn; Prats, Miquel; Lim, Sungwoo; McKay, Alison; Garner, Steve; Chase, Scott; Christine Alvarado and Marie-Paule Cani
    This paper presents research that aims to inform the development of computational tools that better support design exploration and idea transformation - key objectives in conceptual design. Analyses of experimental data from two fields - product design and architecture - suggest that the interactions of designers with their sketches can be formalised according to a finite number of generalised shape rules defined within a shape grammar. Such rules can provide a basis for the generation of alternative design concepts and they have informed the development of a prototype shape synthesis system that supports dynamic reinterpretation of shapes in design activity. The notion of sub-shapes' is introduced and the significance of these to perception, recognition and the development of emergent structures is discussed. The paper concludes with some speculation on how such a system might find application in a range of design fields.
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    Using Sketches and Retrieval to Create LEGO Models
    (The Eurographics Association, 2008) Santos, Tiago; Ferreira, Alfredo; Dias, Filipe; Fonseca, Manuel J.; Christine Alvarado and Marie-Paule Cani
    In this paper we describe a system to create LEGO models using sketches. Although there are a few applications to create LEGO models, they are difficult to use, mainly due to the searching and manipulation mechanisms that they (do not) offer. Here, we propose a sketch based approach, where users can easily insert parts, by specifying their dimensions through sketches and the system suggests a list of possible parts. To help with the modeling and the manipulation we also developed a constraint based mechanism, which keeps parts connected, performs snapto- grid and detects collisions. Experimental tests with users revealed that our approach is easier and faster to use than a conventional application, such as LeoCAD.
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    Rapid Sketch Modeling of Clouds
    (The Eurographics Association, 2008) Wither, Jamie; Bouthors, Antoine; Cani, Marie-Paule; Christine Alvarado and Marie-Paule Cani
    Clouds are an important visual element of any natural scene and computer artists often wish to create specific cloud shapes (for example in the film Amélie, as depicted in Fig 1). We describe a sketch based interface for modeling cumulous clouds. This interface allows rapid construction of a 3D cloud surface representation (mesh) using an underlying point based implicit surface representation. This mesh is rendered using the technique [BNM*08], resulting in a realtime cloud modeling and rendering system.