SBM15: Sketch Based Interfaces and Modeling 2015

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https://diglib.eg.org/handle/10.2312/12610

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    Inverse Toon Shading: Interactive Normal Field Modeling with Isophotes
    (The Eurographics Association, 2015) Xu, Qiuying; Gingold, Yotam; Singh, Karan; Ergun Akleman
    We introduce an interactive modeling tool for designing a smooth 3D normal field from the isophotes of a discretely shaded 2D image. Block or cartoon shading is a visual style in which artists depict a smoothly shaded 3D object using a small number of discrete brightness values, manifested as regions or bands of constant color. In our approach, artists trace isophotes, or curves of constant brightness, along the boundaries between constant color bands. Our algorithm first estimates light directions and computes 3D normals along the object silhouette and at intersections between isophotes from different light sources. We then propagate these 3D normals smoothly along isophotes, and subsequently throughout the interior of the shape. We describe our user interface for editing isophotes and correcting unintended normals produced by our algorithm. We validate our approach with a perceptual experiment and comparisons to ground truth data. Finally, we present a set of 3D renderings created using our interface.
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    SVM-based Sketch Recognition: Which Hyperparameter Interval to Try?
    (The Eurographics Association, 2015) Yesilbek, Kemal Tugrul; Sen, Cansu; Cakmak, Serike; Sezgin, T. Metin; Ergun Akleman
    Hyperparameters are among the most crucial factors that affect the performance of machine learning algorithms. In general, there is no direct method for determining a set of satisfactory parameters, so hyperparameter search needs to be conducted each time a model is to be trained. In this work, we analyze how similar hyperparameters perform across various datasets from the sketch recognition domain. Results show that hyperparameter search space can be reduced to a subspace despite differences in characteristics of datasets.
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    ShipShape: A Drawing Beautification Assistant
    (The Eurographics Association, 2015) Fišer, Jakub; Asente, Paul; Sýkora, Daniel; Ergun Akleman
    Sketching is one of the simplest ways to visualize ideas. Its key advantage is requiring the user to have neither deep knowledge of a particular drawing software nor any advanced drawing skills. In practice, however, all these skills become necessary to improve the visual fidelity of the resulting drawing. In this paper, we present ShipShape-a general beautification assistant that allows users to maintain the simplicity and speed of freehand sketching while still taking into account implicit geometric relations to automatically rectify the output image. In contrast to previous approaches ShipShape works with general Bézier curves, enables undo/redo operations, is scale independent, and is fully integrated into Adobe Illustrator. We demonstrate various results to demonstrate capabilities of the proposed method.
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    Adding Dynamics to Sketch-based Character Animations
    (The Eurographics Association, 2015) Guay, Martin; Ronfard, Rémi; Gleicher, Michael; Cani, Marie-Paule; Ergun Akleman
    Cartoonists and animators often use lines of action to emphasize dynamics in character poses. In this paper, we propose a physically-based model to simulate the line of action's motion, leading to rich motion from simple drawings. Our proposed method is decomposed into three steps. Based on user-provided strokes, we forward simulate 2D elastic motion. To ensure continuity across keyframes, we re-target the forward simulations to the drawn strokes. Finally, we synthesize a 3D character motion matching the dynamic line. The fact that the line can move freely like an elastic band raises new questions about its relationship to the body over time. The line may move faster and leave body parts behind, or the line may slide slowly towards other body parts for support. We conjecture that the artist seeks to maximize the filling of the line (with the character's body)-while respecting basic realism constraints such as balance. Based on these insights, we provide a method that synthesizes 3D character motion, given discontinuously constrained body parts that are specified by the user at key moments.
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    A Combined Junction-Cue Dictionary for Labelling Sketch Drawings with Artistic Shadows and Table-line Cues
    (The Eurographics Association, 2015) Bonnici, Alexandra; Camilleri, Kenneth P.; Ergun Akleman
    The interpretation of user sketches generates research interest in the product design community since the computer interpretation of sketches may reduce the design-to-market time while giving the designer greater flexibility and control of the design process. This paper describes how cues, namely shadows and table lines used to express structural form in the drawing, may be used in a line-labelling algorithm to obtain a drawing interpretation that matches some design intent. To this extent, this paper describes canonical forms of the cues from which a combined junction and cue dictionary is created and used within a genetic algorithm framework to label the drawing. This paper also describes how such cues may be identified from the sketch.
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    Real-Time Activity Prediction: A Gaze-Based Approach for Early Recognition of Pen-Based Interaction Tasks
    (The Eurographics Association, 2015) Çıg, Çagla; Sezgin, Tevfik Metin; Ergun Akleman
    Recently there has been a growing interest in sketch recognition technologies for facilitating human-computer interaction. Existing sketch recognition studies mainly focus on recognizing pre-defined symbols and gestures. However, just as there is a need for systems that can automatically recognize symbols and gestures, there is also a pressing need for systems that can automatically recognize pen-based manipulation activities (e.g. dragging, maximizing, minimizing, scrolling). There are two main challenges in classifying manipulation activities. First is the inherent lack of characteristic visual appearances of pen inputs that correspond to manipulation activities. Second is the necessity of real-time classification based upon the principle that users must receive immediate and appropriate visual feedback about the effects of their actions. In this paper (1) an existing activity prediction system for pen-based devices is modified for real-time activity prediction and (2) an alternative time-based activity prediction system is introduced. Both systems use eye gaze movements that naturally accompany pen-based user interaction for activity classification. The results of our comprehensive experiments demonstrate that the newly developed alternative system is a more successful candidate (in terms of prediction accuracy and early prediction speed) than the existing system for real-time activity prediction. More specifically, midway through an activity, the alternative system reaches 66% of its maximum accuracy value (i.e. 66% of 70.34%) whereas the existing system reaches only 36% of its maximum accuracy value (i.e. 36% of 55.69%).