SBM07: Sketch Based Interfaces and Modeling 2007

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https://diglib7.eg.org/handle/10.2312/419

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Addressing Class Distribution Issues of the Drawing vs Writing Classification in an Ink Stroke Sequence
(The Eurographics Association, 2007) Wang, Xin; Biswas, Manoj; Raghupathy, Sashi; Michiel van de Panne and Eric Saund
Complicated by temporal correlations among the strokes and varying distributions of the underlying classes, the drawing/writing classification of ink strokes in a digital ink file poses interesting challenges. In this paper, we present our efforts in addressing some of the issues. First, we describe how we adjust the outputs of the neural network to a priori probabilities of new observations to produce more accurate estimates of the posterior probabilities. Second, we describe how to adapt the parameters of the HMM to new data sets. Albeit the fact that the emission probabilities of the HMM are computed indirectly from the outputs of the neural network, our modified Baum-Welch algorithm still finds the correct estimates for the HMM's parameters. We also present experimental results of our new algorithms on 6 real world data sets. The results show that our methods increase the F Measures of both the drawing and the writing classes on the more ''drawing intensive'' data sets which have stronger temporal correlations. But they do not perform well on the more ''writing intensive'' data sets.
A Combinatorial Approach to Multi-Domain Sketch Recognition
(The Eurographics Association, 2007) Hall, A.; Pomm, C.; Widmayer, P.; Michiel van de Panne and Eric Saund
In this paper we propose a combinatorial model for sketch recognition. Two fundamental problems, the evaluation of individual symbols and the interpretation of a complete sketch scene possibly containing several symbols, are expressed as combinatorial optimization problems. We settle the computational complexity of the combinatorial problems and present a branch and bound algorithm for computing optimal symbol confidences. To handle sketch scenes in practice we propose a modest restriction of drawing freedom and present an algorithm which only needs to compute a polynomial number of symbol confidences.
CrossSketch: Freeform Surface Modeling with Details
(The Eurographics Association, 2007) Andre, Alexis; Saito, Suguru; Nakajima, Masayuki; Michiel van de Panne and Eric Saund
This paper presents a novel technique to model a three dimensional freeform surface, in its global shape and small details, using a sketching interface, from a single point of view. In the past, most modeling systems that used sketches as input reconstructed the shape from the silhouette, and the user had few control on the inner parts of the result. In our system, we generate a grid of co-planar lines from a small number of strokes that the user drew, then we estimate the normal vector where it is constrained, and we form the surface by propagating this information to the whole grid. As a result, smaller strokes act locally to add detail, while longer strokes modify the whole surface. Our system gives a new approach to the modeling from sketches problem, and is intended to be a part of a more complex modeling system.
Designing a Sketch Recognition Front-End: User Perception of Interface Elements
(The Eurographics Association, 2007) Wais, Paul; Wolin, Aaron; Alvarado, Christine; Michiel van de Panne and Eric Saund
Programs that can recognize students' hand-drawn diagrams have the potential to revolutionize education by breaking down the barriers between diagram creation and simulation. Much recent work focuses on building robust recognition engines, but understanding how to support this new interaction paradigm from a user's perspective is an equally important and less well understood problem. We present a user study that investigates four critical sketch recognition user interface issues: how users integrate the process of triggering recognition into their work, when users prefer to indicate which portions of the diagram should be recognized, how users prefer to receive recognition feedback, and how users perceive recognition errors. We find that user preferences emphasize the importance of system reliability, the minimization of distractions, and the maximization of predictability.
Designing UI Techniques for Handwritten Mathematics
(The Eurographics Association, 2007) Zeleznik, Robert; Miller, Timothy; Li, Chuanjun; Michiel van de Panne and Eric Saund
We discuss the design of user interface techniques for visualizing and controlling the recognition of handwritten mathematics. In particular, we present a range of visualization styles for displaying the result of math recognition. These styles offer different trade-offs between ease of user correction of errors in recognition and impact on the user's entry of math. We also describe recognition control techniques, including using user-controlled mappings of allographs to achieve more robust symbol recognition and provide extensions to notation, and UI control of non-spatial information used in recognition. We generally do not discuss the precise user interface implementation necessary to use these techniques, for example whether to use menus or gestures, but just the functionality required. Finally, we provide, in an appendix, a sketch of the recognition and display implementation behind our techniques.
Example-Based Conceptual Styling Framework for Automotive Shapes
(The Eurographics Association, 2007) Kókai, István; Finger, Jörg; Smith, Randall C.; Pawlicki, Richard; Vetter, Thomas; Michiel van de Panne and Eric Saund
Conceptual design in the automotive industry is a time-consuming process. Iterations between concept sketches, created with traditional two dimensional methods, and 3D digital representations of a prototype are currently one of the big bottlenecks. In this paper we present a framework for an integrated 2D-3D design environment. The core of the framework is a model representing the characteristic lines of automotive shapes built from a set of example shapes. From every example shape we extract the same set of characteristic lines and represent them with a feature vector of deformation gradients. Given a set of constraints, our method can generate a new feature vector with an optimization procedure. We provide examples for meaningful manipulations. We demonstrate that these manipulations are intuitive and create plausible shapes.
Free-form Sketch
(The Eurographics Association, 2007) Wang, Haixiong; Markosian, Lee; Michiel van de Panne and Eric Saund
We describe a sketch-based system for modeling 3D shapes based on a new multiresolution shape representation we call a layered mesh. Like subdivision surfaces, layered meshes provide a multiresolution hierarchy of meshes. A key difference is that a layered mesh lets you edit the shape and structure of the mesh at any level of the hierarchy, through the notion of shape primitives organized in a dependency network. The simplest primitives are points and curves, which can be used to define several kinds of parameteric surface. Surfaces can be inflated or smoothly joined to produce a broad range of shapes. An important feature of the system is the ability to refine shapes and add detail by oversketching primitives, either directly or via the curves that define them. While our user interface is still in development, our initial results show the potential for this approach.
Implicit Geometric Constraint Detection in Freehand Sketches Using Relative Shape Histogram
(The Eurographics Association, 2007) Pu, J.; Ramani, K.; Michiel van de Panne and Eric Saund
In order to take advantage of the sketch-based interaction, many methods have been proposed to beautify freehand sketches. Most of these efforts are dedicated to sketch segmentation and recognition, while some important information implied in the sketches, such as geometric constraints, are largely ignored. Thus, the final beautified results by these methods do not fully reflect the true intentions from users. In this paper, a statistical approach called Relative Shape Histogram (RSH) is introduced to detect the implied geometric constraint in sketches. The basic idea arises from such a discovery that the same geometric constraints between two geometric primitives have similar relative shape histograms. By computing the similarity between RSHs, the implicit geometric constraints between two segmented primitives are inferred. To evaluate the performance of the proposed algorithm, a userbased experiment is conducted and the results are presented in this paper.
Ink Features for Diagram Recognition
(The Eurographics Association, 2007) Patel, Rachel; Plimmer, Beryl; Grundy, John; Ihaka, Ross; Michiel van de Panne and Eric Saund
The ability to automatically recognize a sketch accurately is important to computer-based diagramming. Many recognition techniques have been proposed but few researchers have reported the use of formal methods to select the most appropriate ink features for recognition algorithms. We have used a statistical approach to identify the most important distinguishing features of ink for dividing text and shapes. We implemented these into an existing recognition engine and conducted a comparative evaluation. Our feature set more successfully classified a range of common diagram elements than two existing dividers.
Kirchhoff's Pen: A Pen-based Circuit Analysis Tutor
(The Eurographics Association, 2007) Silva, Ruwanee de; Bischel, David Tyler; Lee, WeeSan; Peterson, Eric J.; Calfee, Robert C.; Stahovich, Thomas F.; Michiel van de Panne and Eric Saund
Kirchhoff 's Pen is a pen-based tutoring system that teaches students to apply Kirchhoff 's voltage law (KVL) and current law (KCL). To use the system, the student sketches a circuit schematic and annotates it to indicate component labels, mesh currents, and nodal voltages. The student then selects either mesh (KVL) or nodal (KCL) analysis, and writes the appropriate equations. The system interprets the equations, compares them to the correct equations (which are automatically derived from the circuit), and provides tutorial feedback about errors. Unlike traditional tutoring systems that work from input provided with a keyboard and mouse, our system works from ambiguous, hand-drawn input. The goal of our work is to create computational techniques to enable natural, pen-based tutoring systems that scaffold students in solving problems in the same way they would ordinarily solve them with paper and pencil. Kirchhoff's Pen is an important first step toward this goal.
Managing Ambiguity in Mathematical Matrices
(The Eurographics Association, 2007) Tausky, David; Labahn, George; Lank, Edward; Marzouk, Mirette; Michiel van de Panne and Eric Saund
In this paper we describe strategies for recognizing and using hand drawn matrices in a pen math system. This includes a new technique to recognize common short-forms of writing matrices using ellipsis (. . . ). Ellipsis are commonly used in sketched matrices to illustrate the structure of a matrix without fully specifying the matrix. A second contribution of this paper is a new method to estimate the parameters of the hand drawn matrix, such as the number and position of the rows and columns. This is done using a modified clustering algorithm, allowing one to reduce the number of hard-coded constraints.
Newton's Pen - A Pen-based Tutoring System for Statics
(The Eurographics Association, 2007) Lee, WeeSan; Silva, Ruwanee de; Peterson, Eric J.; Calfee, Robert C.; Stahovich, Thomas F.; Michiel van de Panne and Eric Saund
We present Newton's Pen, a statics tutor implemented on a ''pentop computer,'' a writing instrument with an integrated digitizer and embedded processor. The tutor, intended for undergraduate education, scaffolds students in the construction of free body diagrams and equilibrium equations. This project entailed the development of sketch understanding techniques and user interface principles for creating pedagogically-sound instructional tools for pentop computers. Development on the pentop platform presented novel challenges because of limited computational resources and a visually static, ink-on-paper display (the only dynamic output device is an audio speaker). We show that a system architecture based on a finite state machine reduces the computational complexity, and serves as a convenient means for providing context-sensitive tutorial help. Our pilot study suggests that Newton's Pen has potential as an effective teaching tool.
A Pen-based Tool for Efficient Labeling of 2D Sketches
(The Eurographics Association, 2007) Wolin, Aaron; Smith, Devin; Alvarado, Christine; Michiel van de Panne and Eric Saund
High quality labeled data is essential for developing and evaluating sketch recognition algorithms. Unfortunately, labeling freely-drawn sketches is time-consuming and difficult, if not impossible, using current technologies. These difficulties and the resulting lack of labeled data fundamentally limit the development of recognition algorithms.We present an intuitive, direct manipulation pen-based application for labeling sketch data in any two-dimensional domain. Our labeling tool supports the three essential sketch recognition labeling tasks: stroke fragmentation, stroke grouping and label application. Our interface integrates standard and novel interaction techniques to make each task efficient and natural. In a user study, all users felt that labeling data with our tool was quick and efficient.
Scribbles to Vectors: Preparation of Scribble Drawings for CAD Interpretation
(The Eurographics Association, 2007) Bartolo, A.; Camilleri, K. P.; Fabri, S. G.; Borg, J. C.; Farrugia, P. J.; Michiel van de Panne and Eric Saund
This paper describes the work carried out on off-line paper based scribbles such that they can be incorporated into a sketch-based interface without forcing designers to change their natural drawing habits. In this work, the scribbled drawings are converted into a vectorial format which can be recognized by a CAD system. This is achieved by using pattern analysis techniques, namely the Gabor filter to simplify the scribbled drawing. Vector line are then extracted from the resulting drawing by means of Kalman filtering.
SilSketch: Automated Sketch-Based Editing of Surface Meshes
(The Eurographics Association, 2007) Zimmermann, Johannes; Nealen, Andrew; Alexa, Marc; Michiel van de Panne and Eric Saund
We introduce an over-sketching interface for feature-preserving surface mesh editing. The user sketches a stroke that is the suggested position of part of a silhouette of the displayed surface. The system then segments all imagespace silhouettes of the projected surface, identifies among all silhouette segments the best matching part, derives vertices in the surface mesh corresponding to the silhouette part, selects a sub-region of the mesh to be modified, and feeds appropriately modified vertex positions together with the sub-mesh into a mesh deformation tool. The overall algorithm has been designed to enable interactive modification of the surface yielding a surface editing system that comes close to the experience of sketching 3D models on paper.
Sketching Hairstyles
(The Eurographics Association, 2007) Fu, Hongbo; Wei, Yichen; Tai, Chiew-Lan; Quan, Long; Michiel van de Panne and Eric Saund
This paper presents an intuitive sketching interface for interactive hairstyle design, made possible by an efficient numerical updating scheme. The user portrays the global shape of a desired hairstyle through a few 3D style curves which are manipulated by interactively sketching freeform strokes. Our approach is based on a vector field representation which is obtained by solving a sparse linear system with the style curves acting as boundary constraints. The key observation is that the specific sparseness pattern of the linear system enables an efficient incremental numerical updating scheme. This gives rise to a sketching interface that provides interactive visual feedback to the user. Interesting hairstyles can be easily created in minutes.
Speech and Sketching: An Empirical Study of Multimodal Interaction
(The Eurographics Association, 2007) Adler, A.; Davis, R.; Michiel van de Panne and Eric Saund
Sketch recognition can capture the sketching component of a multimodal conversation about design, but it does not capture information conveyed in the other modalities. The informal speech that accompanies a sketch often has a considerable amount of additional information. We want to develop a digital whiteboard capable of understanding both sketching and speech, and capable of participating in a conversation similar to one that the user would have with a human design partner. We conducted a user study to help us understand what kinds of conversations users would have with a whiteboard capable of recognizing a sketch. We report results that we believe will help guide the design of an effective multimodal interface, and discuss implications for system architectures.
Temporal Sketch Recognition in Interspersed Drawings
(The Eurographics Association, 2007) Sezgin, Tevfik Metin; Davis, Randall; Michiel van de Panne and Eric Saund
Sketch recognition has been recognized as an enabling technology for pen-based interfaces. Previous work in the field has shown that in certain domains the stroke orderings used when drawing objects contain temporal patterns that can aid recognition. So far, systems that use temporal information for recognition have assumed that objects are drawn one at a time. This paper shows how this assumption can be relaxed to permit temporal interspersing of strokes from different objects. We describe a statistical framework based on Dynamic Bayesian Networks that explicitly models the fact that objects can be drawn interspersed. We present recognition results for hand-drawn electronic circuit diagrams. The results show that handling interspersed drawing provides a significant increase in accuracy.

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