Publication statistics

Pub. period:1999-2012
Pub. count:23
Number of co-authors:34


Number of publications with 3 favourite co-authors:

Rajiv Maheswaran:
Yan Wang:
Huihui Cheng:



Productive colleagues

Karan Singh's 3 most productive colleagues in number of publications:

Ravin Balakrishnan:108
Gordon Kurtenbach:45
Tovi Grossman:44

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Karan Singh


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Current place of employment:
University of Toronto

Karan Singh is an an Associate Professor in Computer Science at the University of Toronto. He holds a BTech. from IIT Madras, MS, PhD from the Ohio State University. His research interests lie in artist driven interactive graphics, spanning character animation, anatomic modeling, geometric shape design and sketch-based interfaces. He has been a technical lead the Oscar winning animation system Maya. He co-directs the graphics and human computer interaction lab, DGP and was the R&D Director for the 2005 Oscar winning Animation film Ryan.


Publications by Karan Singh (bibliography)

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Szekely, Pedro, Chang, Yu-Han, Maheswaran, Rajiv, Wang, Yan, Cheng, Huihui and Singh, Karan (2012): Interactive uncertainty analysis. In: Proceedings of the 2012 International Conference on Intelligent User Interfaces 2012. pp. 269-272.

Humans have difficulty evaluating the effects of uncertainty on schedules. People often mitigate the effects of uncertainty by adding slack based on experience and non-stochastic analyses such as the critical path method (CPM). This is costly as it leads to longer than necessary schedules, and can be ineffective without a clear understanding of where slack is needed. COMPASS is an interactive real-time tool that analyzes schedule uncertainty for a stochastic task network. An important feature is that it concurrently calculates stochastic critical paths and critical tasks. COMPASS visualizes this information on top of a traditional Gantt view, giving users insight into how delays caused by uncertain durations propagate down the schedule. Evaluations with 10 users show that users can use COMPASS to answer a variety of questions about the possible evolutions of a schedule (e.g., what is the likelihood that all activities will complete before a given date?)

© All rights reserved Szekely et al. and/or ACM Press

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Zarek, Adam, Wigdor, Daniel and Singh, Karan (2012): SNOUT: one-handed use of capacitive touch devices. In: Proceedings of the 2012 International Conference on Advanced Visual Interfaces 2012. pp. 140-147.

SNOUT is a novel interface overlay designed for occasional no-hand or one-handed use of handheld capacitive touch devices. Inspired by the desire to use these devices in scenarios where visually focused bimanual input is awkward, we performed a pair of studies intended to evaluate the potential of the nose to provide touch input. These studies influenced our design principles, resulting in the construction of a 'nose mode' which enables object selection, continuous parameter control, and speech-based text entry. Selection is accomplished via a nose tap, using a colour overlay and peripheral colour feedback to correct mistakes. The other two techniques are activated by a nose tap, but use the accelerometer to control parameters and speech-to-text for text entry. An evaluation of SNOUT shows it to effectively render handheld capacitive touch devices operational in scenarios where they are presently unusable.

© All rights reserved Zarek et al. and/or ACM Press

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Rahgoshay, Cyrus, Rabbani, Amir, Singh, Karan and Kry, Paul G. (2012): Inverse kinodynamics: editing and constraining kinematic approximations of dynamic motion. In: Proceedings of the 2012 Conference on Graphics Interface 2012. pp. 185-192.

We present inverse kinodynamics (IKD), an animator friendly kinematic workflow that both encapsulates short-lived dynamics and allows precise space-time constraints. Kinodynamics (KD), defines the system state at any given time as the result of a kinematic state in the recent past, physically simulated over a short temporal window to the present. KD is a well suited kinematic approximation to animated characters and other dynamic systems with dominant kinematic motion and short-lived dynamics. Given a dynamic system, we first choose an appropriate kinodynamic window size based on accelerations in the kinematic trajectory and the physical properties of the system. We then present an inverse kinodynamics (IKD) algorithm, where a kinodynamic system can precisely attain a set of animator constraints at specified times. Our approach solves the IKD problem iteratively, and is able to handle full pose or end effector constraints at both position and velocity level, as well as multiple constraints in close temporal proximity. Our approach can also be used to solve position and velocity constraints on passive systems attached to kinematically driven bodies. We show IKD to be a compelling approach to the direct kinematic control of character, with secondary dynamics via examples of skeletal dynamics and facial animation.

© All rights reserved Rahgoshay et al. and/or their publisher

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Thiel, Yannick, Singh, Karan and Balakrishnan, Ravin (2011): Elasticurves: exploiting stroke dynamics and inertia for the real-time neatening of sketched 2D curves. In: Proceedings of the 2011 ACM Symposium on User Interface Software and Technology 2011. pp. 383-392.

Elasticurves present a novel approach to neaten sketches in real-time, resulting in curves that combine smoothness with user-intended detail. Inspired by natural variations in stroke speed when drawing quickly or with precision, we exploit stroke dynamics to distinguish intentional fine detail from stroke noise. Combining inertia and stroke dynamics, elasticurves can be imagined as the trace of a pen attached to the user by an oscillation-free elastic band. Sketched quickly, the elasticurve spatially lags behind the stroke, smoothing over stroke detail, but catches up and matches the input stroke at slower speeds. Connectors, such as lines or circular-arcs link the evolving elasticurve to the next input point, growing the curve by a responsiveness fraction along the connector. Responsiveness is calibrated, to reflect drawing skill or device noise. Elasticurves are theoretically sound and robust to variations in stroke sampling. Practically, they neaten digital strokes in real-time while retaining the modeless and visceral feel of pen on paper.

© All rights reserved Thiel et al. and/or ACM Press

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McCrae, James, Glueck, Michael, Grossman, Tovi, Khan, Azam and Singh, Karan (2010): Exploring the design space of multiscale 3D orientation. In: Proceedings of the 2010 International Conference on Advanced Visual Interfaces 2010. pp. 81-88.

Recently, research in 3D computer graphics and interaction has started to move beyond the narrow domain of single object authoring and inspection, and has begun to consider complex multiscale objects and environments. This generalization of problem scope calls for more general solutions, which are more akin to information visualization techniques than traditional computer graphics approaches. We consider the general problem of the user's understanding of their position and orientation within a multiscale 3D scene and propose a classification of the design space. To ground this theoretical discussion, we present initial explorations into grouping techniques, visualizations, and interactions to facilitate multiscale 3D orientation.

© All rights reserved McCrae et al. and/or their publisher

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McCrae, James and Singh, Karan (2009): Sketch-based path design. In: Proceedings of the 2009 Conference on Graphics Interface 2009. pp. 95-102.

We present Drive, a system for the conceptual layout of 3D path networks. Our sketch-based interface allows users to efficiently author path layouts with minimal instruction. Our system incorporates some new and noteworthy components. We present the break-out lens, a novel widget for interactive graphics, inspired by break-out views used in engineering visualization. We also make three contributions specific to path curve design: First, we extend our previous work to fit aesthetic paths to sketch strokes with constraints, using piecewise clothoid curves. Second, we determine the height of paths above the terrain using a constraint optimization formulation of the occlusion relationships between sketched strokes. Finally, we illustrate examples of terrain sensitive path construction in the context of road design: automatically removing foliage, building bridges and tunnels across topographic features and constructing road signs appropriate to the sketched paths.

© All rights reserved McCrae and Singh and/or their publisher

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Bae, Seok-Hyung, Balakrishnan, Ravin and Singh, Karan (2009): EverybodyLovesSketch: 3D sketching for a broader audience. In: Proceedings of the ACM Symposium on User Interface Software and Technology 2009. pp. 59-68.

We present EverybodyLovesSketch, a gesture-based 3D curve sketching system for rapid ideation and visualization of 3D forms, aimed at a broad audience. We first analyze traditional perspective drawing in professional practice. We then design a system built upon the paradigm of ILoveSketch, a 3D curve drawing system for design professionals. The new system incorporates many interaction aspects of perspective drawing with judicious automation to enable novices with no perspective training to proficiently create 3D curve sketches. EverybodyLovesSketch supports a number of novel interactions: tick-based sketch plane selection, single view definition of arbitrary extrusion vectors, multiple extruded surface sketching, copy-and-project of 3D curves, freeform surface sketching, and an interactive perspective grid. Finally, we present a study involving 49 high school students (with no formal artistic training) who each learned and used the system over 11 days, which provides detailed insights into the popularity, power and usability of the various techniques, and shows our system to be easily learnt and effectively used, with broad appeal.

© All rights reserved Bae et al. and/or their publisher

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McCrae, James and Singh, Karan (2009): Sketching piecewise clothoid curves. In Computers & Graphics, 33 (4) pp. 452-461.

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Dragicevic, Pierre, Ramos, Gonzalo, Bibliowitcz, Jacobo, Nowrouzezahrai, Derek, Balakrishnan, Ravin and Singh, Karan (2008): Video browsing by direct manipulation. In: Proceedings of ACM CHI 2008 Conference on Human Factors in Computing Systems April 5-10, 2008. pp. 237-246.

We present a method for browsing videos by directly dragging their content. This method brings the benefits of direct manipulation to an activity typically mediated by widgets. We support this new type of interactivity by: 1) automatically extracting motion data from videos; and 2) a new technique called relative flow dragging that lets users control video playback by moving objects of interest along their visual trajectory. We show that this method can outperform the traditional seeker bar in video browsing tasks that focus on visual content rather than time.

© All rights reserved Dragicevic et al. and/or ACM Press

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Bae, Seok-Hyung, Balakrishnan, Ravin and Singh, Karan (2008): ILoveSketch: as-natural-as-possible sketching system for creating 3d curve models. In: Cousins, Steve B. and Beaudouin-Lafon, Michel (eds.) Proceedings of the 21st Annual ACM Symposium on User Interface Software and Technology October 19-22, 2008, Monterey, CA, USA. pp. 151-160.

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Schmidt, Ryan, Singh, Karan and Balakrishnan, Ravin (2008): Sketching and Composing Widgets for 3D Manipulation. In Comput. Graph. Forum, 27 (2) pp. 301-310.

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Schmidt, Ryan and Singh, Karan (2008): Sketch-Based Procedural Surface Modeling and Compositing Using Surface Trees. In Comput. Graph. Forum, 27 (2) pp. 321-330.

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Coleman, Patrick and Singh, Karan (2006): Cords: Geometric Curve Primitives for Modeling Contact. In IEEE Computer Graphics and Applications, 26 (3) pp. 72-79.

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Simari, Patricio D. and Singh, Karan (2005): Extraction and remeshing of ellipsoidal representations from mesh data. In: Graphics Interface 2005 May 9-11, 2005, Victoria, British Columbia, Canada. pp. 161-168.

Dense 3D polygon meshes are now a pervasive product of various modelling and scanning processes that need to be subsequently processed and structured appropriately for various applications. In this paper we address the restructuring of dense polygon meshes using their segmentation based on a number of ellipsoidal regions. We present a simple segmentation algorithm where connected components of a mesh are fit to ellipsoidal surface regions. The segmentation of a mesh into a small number of ellipsoidal elements makes for a compact geometric representation and facilitates efficient geometric queries and transformations. We also contrast and compare two polygon remeshing techniques based on the ellipsoidal surfaces and the segmentation boundaries.

© All rights reserved Simari and Singh and/or their publisher

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Laszlo, Joe, Neff, Michael and Singh, Karan (2005): Predictive Feedback for Interactive Control of Physics-based Characters. In Comput. Graph. Forum, 24 (3) pp. 257-265.

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Tsang, Steve, Balakrishnan, Ravin, Singh, Karan and Ranjan, Abhishek (2004): A suggestive interface for image guided 3D sketching. In: Dykstra-Erickson, Elizabeth and Tscheligi, Manfred (eds.) Proceedings of ACM CHI 2004 Conference on Human Factors in Computing Systems April 24-29, 2004, Vienna, Austria. pp. 591-598.

We present an image guided pen-based suggestive interface for sketching 3D wireframe models. Rather than starting from a blank canvas, existing 2D images of similar objects serve as a guide to the user. Image based filters enable attraction, smoothing, and resampling of input curves, and allows for their selective application using pinning and gluing techniques. New input strokes also invoke suggestions of relevant geometry that can be used, reducing the need to explicitly draw all parts of the new model. All suggestions appear in-place with the model being built, in the user's focal attention space. A curve matching algorithm seamlessly augments basic suggestions with more complex ones from a database populated with previously used geometry. The interface also incorporates gestural command input, and interaction techniques for camera controls that enable smooth transitions between orthographic and perspective views.

© All rights reserved Tsang et al. and/or ACM Press

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Singh, Karan, Grimm, Cindy and Sudarsanam, Nisha (2004): The IBar: a perspective-based camera widget. In: Proceedings of the 2004 ACM Symposium on User Interface Software and Technology 2004. pp. 95-98.

We present a new screen space widget, the IBar, for effective camera control in 3D graphics environments. The IBar provides a compelling interface for controlling scene perspective based on the artistic concept of vanishing points. Various handles on the widget manipulate multiple camera parameters simultaneously to create a single perceived projection change. For example, changing just the perspective distortion is accomplished by simultaneously decreasing the camera\'s distance to the scene while increasing focal length. We demonstrate that the IBar is easier to learn for novice users and improves their understanding of camera perspective.

© All rights reserved Singh et al. and/or ACM Press

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Grossman, Tovi, Balakrishnan, Ravin and Singh, Karan (2003): An interface for creating and manipulating curves using a high degree-of-freedom curve input device. In: Cockton, Gilbert and Korhonen, Panu (eds.) Proceedings of the ACM CHI 2003 Human Factors in Computing Systems Conference April 5-10, 2003, Ft. Lauderdale, Florida, USA. pp. 185-192.

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Singh, Karan (2002): A Fresh Perspective. In: Graphics Interface 2002 May 27-29, 2002, Calgary, Alberta, Canada. pp. 17-24.

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Singh, Karan and Parent, Richard E. (2001): Joining polyhedral objects using implicitly defined surfaces. In The Visual Computer, 17 (7) pp. 415-428.

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Singh, Karan and Kokkevis, Evangelos (2000): Skinning Characters using Surface Oriented Free-Form Deformations. In: Proceedings of Graphics Interface 2000 May 15-17, 2000, Montreal, Quebec, Canada. pp. 35-42.

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Balakrishnan, Ravin, Fitzmaurice, George W., Kurtenbach, Gordon and Singh, Karan (1999): Exploring interactive curve and surface manipulation using a bend and twist sensitive input strip. In: SI3D 1999 1999. pp. 111-118.

 Cited in the following chapter:

: [Not yet published]

 Cited in the following chapter:

: [Not yet published]

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Singh, Karan (1999): Interactive curve design using digital French curves. In: SI3D 1999 1999. pp. 23-30.

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