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Now showing 1 - 10 of 18
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    Defining Precise Measurements with Sketched Annotations
    (The Eurographics Association, 2011) Kebodeaux, Kourtney; Field, Martin; Hammond, Tracy; Tracy Hammond and Andy Nealen
    Technology has been largely employed in the modern education system but rarely fosters natural communication between the human and the machine. We wish to explore the use of sketch recognition based software as a medium for student computer interaction within the context of computer assisted tutoring systems. Since the student can draw directly on the screen in this scenario, the interaction mimics familiar pencil and paper techniques while the speed and one-on-one attention of the computer alleviate some of the challenges currently faced by students and teachers in a traditional education setting. Furthermore, we wish to promote the incorporation of more free response questions ( build a structure to meet these requirements instead of analyze this structure ) into the modern curriculum. These types of questions are rare because of how difficult they are to grade, but more closely approximate reality and provide context for the ethodologies learned in the classroom. Free response questions require a large degree of flexibility and an overall more intelligent tutoring system than has been previously studied. Mechanix is a sketch recognition based tutoring system that provides immediate feedback for engineering statics problems. In order to extend Mechanix to support free response problems, the software needs to know the precise physical properties of sketched elements. We ntroduce measurement mechanisms such that, with minimal effort, a user may specify the precise measurements of a truss, so that Mechanix can create and solve systems of equations to determine how forces are distributed throughout the truss. Therefore, given a sketched truss and measurements as a response to a free response questions, the system may determine whether the structure satisfies the requirements of the question.
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    StereoBrush: Interactive 2D to 3D Conversion UsingDiscontinuous Warps
    (The Eurographics Association, 2011) Wang, O.; Lang, M.; Frei, M.; Hornung, A.; Smolic, A.; Gross, M.; Tracy Hammond and Andy Nealen
    We introduce a novel workflow for stereoscopic 2D to 3D conversion in which the user “paints” depth onto a 2D image via sparse scribbles, instantaneously receiving intuitive 3D feedback. This workflow is enabled by the introduction of a discontinuous warping technique that creates stereoscopic pairs from sparse, possibly erroneous user input. Our method assumes a piecewise continuous depth representation, preserving visual continuity in most areas, while creating sharp depth discontinuities at important object boundaries. As opposed to prior work thatrelies strictly on a per pixel depth map, our scribbles are processed as soft constraints in a global solve and operate entirely on image domain disparity, allowing for relaxed input requirements. This formulation also allows us to simultaneously compute a disparity-and-content-aware stretching of background areas to automatically fill disoccluded regions with valid stereo information. We tightly integrate all steps of stereo content conversion into a single optimization framework, which can then be solved on a GPU at interactive rates. The instant feedback received while painting depth allows even untrained users to quickly create compelling 3D scenes from single-view footage.
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    Is the iPad useful for sketch input? A comparison with the Tablet PC
    (The Eurographics Association, 2011) MacLean, S.; Tausky, D.; Labahn, G.; Lank, E.; Marzouk, M.; Tracy Hammond and Andy Nealen
    Despite the increasing prevalence of touch-based tablet devices, little attention has been paid to what effects, if any, this form factor has on sketch behaviours in general and on sketch recognizers in particular.We investigate the title question through an empirical study in the context of mathematical expression recognition. Using a corpus of thirty expressions drawn on Tablet PC and iPad by thirty writers, we show that characteristics of sketching and drawingdiffer depending on platform. While recognition is most accurate on the Tablet PC due to its technical superiority, recognition is feasible on mobile touch-based devices. However, there are characteristics of sketching on multitouch tablets that differ, and these physical characteristics of writing impact recognition accuracy. Together, ourobservations inform the broader Sketch Recognition community as they design systems targeted to multi-touch tablets.
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    How to make a Quick$: Using Hierarchical Clustering toImprove the Efficiency of the Dollar Recognizer
    (The Eurographics Association, 2011) Reaver, J.; Stahovich, T. F.; Herold, J.; Tracy Hammond and Andy Nealen
    We present Quick$ (QuickBuck), an extension to the Dollar Recognizer designed to improve recognition efficiency. While the Dollar Recognizer must search all training templates to recognize an unknown symbol, Quick$ employs hierarchical clustering along with branch and bound search to do this more efficiently. Experiments have demonstrated that Quick$ is almost always faster than the Dollar Recognizer and always selects the same best-match templates.
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    Neatening sketched strokes using piecewise French Curves
    (The Eurographics Association, 2011) McCrae, James; Singh, Karan; Tracy Hammond and Andy Nealen
    We apply traditional bimanual curve modeling using French curves to the problem of automatic neatening of sketched strokes. Given a sketched input stroke and a set of template French curves we present an approach that fits the stroke using an optimal number of French curve segments. Our algorithm operates in both curvature andpoint space, reconstructing the salient curvature profiles of French curve segments, while limiting error accumulation resulting from curvature integration. User-controlled parameters allow the neatened stroke to model G2 continuous curves, capture G1 discontinuities, define closed curves and explore the trade-off between fitting errorand the number of French curve segments used. We present an interactive sketch stroke neatening implementation to demonstrate the real-time performance of our algorithm and evaluate the quality of its results.
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    Combining Corners from Multiple Segmenters
    (The Eurographics Association, 2011) Wolin, Aaron; Field, Martin; Hammond, Tracy; Tracy Hammond and Andy Nealen
    Pen-based interfaces utilize sketch recognition in order to allow users to sketch complex systems with intuitive input. In order to allow users to freely draw their ideas without constraints, the low-level techniques involved with sketch recognition must be perfected because poor low-level accuracy can impair a user s interaction experience. Stroke segmentation algorithms often employ single, specific techniques in their attempts to splice strokes into primitives used for visual shape representations. These algorithms each have their strengths and weaknesses, and different segmenters find and miss different corners. We introduce a technique to combine polyline corner results from different segmenters by using a variation offeature subset selection. Our feature subset selection algorithm uses a sequential floating backward selection with a mean-squared error objective function in order to find the best subset of corners. By utilizing our combination method, we were able to achieve all-or-nothing accuracies of 0.926 on polyline stroke data.
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    A Sketch-Based System for Highway Design
    (The Eurographics Association, 2011) Applegate, C. S.; Laycock, S. D.; Day, A. M.; Tracy Hammond and Andy Nealen
    To create traffic simulations of high visual-fidelity, each road needs to be designed and modelled in great detail to conform with the governing rules and regulations of highway design. Roads could be created manually, but this can become a time-consuming and laborious process when modelling large-scale networks. Therefore, automated techniques for generating road networks efficiently and effectively, without any prior user knowledge of road design principles and practices, is highly desirable in both urban-planning and entertainment industries. In this paper, we present a novel sketch-based tool to semi-automate the design, creation and visualisation of realistic road networks across both flat and undulating terrains. Our tool is guided by input sketches and a combination of prioritised constraints, including the curvature of roads, their inclination, and the volume of ground that wouldbe displaced during construction. Furthermore, we present an extension to a cellular automata traffic behaviour model that utilises more accurate car-following rules to simulate large-scale networks with high visual-fidelity.
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    Sketch-Based Modeling of Smooth Surfaces Using AdaptiveCurve Networks
    (The Eurographics Association, 2011) Orbay, Günay; Kara, Levent Burak; Tracy Hammond and Andy Nealen
    We present a new 3D surface modeling method that enables a rapid creation and modification of globally smooth surfaces from curve networks. The key feature of the proposed method is that it assumes the sketched curve networks to be malleable rather than rigid, thus enabling a mediation between curve interpolation versus surfacesmoothness. In the first step, the user sketches a network topology in the form of cubic feature edges. The curve network serves as an initial control mesh, from which a subdivision surface is computed. The subdivision surface is then iteratively modified to make the limit surface interpolate the original curve network at an arbitrary numberof points, while minimizing the curvature variation energy of the surface. For networks in which this forced interpolation causes undesirable distortions to the surface, the network is automatically adjusted to make it conform to a smoothed version of the surface. This approach enables a concurrent modeling of the curve network and the underlying surface, thus eliminating the need for a laborious, iterative adjustment of the curve network for smoothsurface creation
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    Continuous Recognition and Visualization of Pen Strokes and Touch-Screen Gestures
    (The Eurographics Association, 2011) Kristensson, P.O.; Denby, L.C.; Tracy Hammond and Andy Nealen
    We present a technique that enables continuous recognition and visualization of pen strokes and touch-screen gestures. We describe an incremental recognition algorithm that provides probability distributions over template classes as a function of users partial or complete stroke articulations. We show that this algorithm can predictusers intended template classes with high accuracy on several different datasets. We use the algorithm to design two new visualizations that reveal various aspects of the recognition process to users. We then demonstrate how these visualizations can help users to understand how the recognition process interprets their input and how interactions between different template classes affect recognition outcomes.
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    Sketch Express: Facial Expressions Made Easy
    (The Eurographics Association, 2011) Miranda, José Carlos; Alvarez, Xenxo; Orvalho, João; Gutierrez, Diego; Sousa, A. Augusto; Orvalho, Verónica; Tracy Hammond and Andy Nealen
    Finding an effective control interface to manipulate complex eometric objects has traditionally relied on experienced users to place the animation controls. This process, whether for key framed or for motion captured animation, takes a lot of time and effort. We introduce a novel sketching interface control system inspired in theway artists draw, in which a stroke defines the shape of an object and reflects the user s intention. We also introduce the canvas, a 2D drawing region where the users can make their strokes, which determines the domain of interaction with the object. We show that the combination of strokes and canvases provides a new way to manipulate the shape of an implicit volume in space. And most importantly, it is independent from the 3D model rig. The strokes can be easily stored and reused in other characters, allowing retargeting of poses. Our interactive approach is illustrated using facial models of different styles. As a result, we allow rapid manipulation of 3D faceson the fly in a very intuitive and interactive way. Our informal study showed that first time users typically master the system within seconds, creating appealing 3D poses and animations in just a few minutes.