Number of co-authors:28
Number of publications with 3 favourite co-authors:Daniel Vogel:6Nicolas Roussel:5Anatole Lecuyer:4
Géry Casiez's 3 most productive colleagues in number of publications:Carl Gutwin:116Ravin Balakrishnan:108Andy Cockburn:68
A user will find any interface design intuitive...with enough practice.
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Publications by Géry Casiez (bibliography)
Araůjo, Bruno R. De, Casiez, Géry and Jorge, Joaquim A. (2012): Mockup builder: direct 3D modeling on and above the surface in a continuous interaction space. In: Proceedings of the 2012 Conference on Graphics Interface 2012. pp. 173-180.
Our work introduces a semi-immersive environment for conceptual design where virtual mockups are obtained from gestures we aim to get closer to the way people conceive, create and manipulate three-dimensional shapes. We present on-and-above-the-surface interaction techniques following Guiard's asymmetric bimanual model to take advantage of the continuous interaction space for creating and editing 3D models in a stereoscopic environment. To allow for more expressive interactions, our approach continuously combines hand and finger tracking in the space above the table with multi-touch on its surface. This combination brings forth an alternative design environment where users can seamlessly switch between interacting on the surface or in the space above it depending on the task. Our approach integrates continuous space usage with bimanual interaction to provide an expressive set of 3D modeling operations. Preliminary trials with our experimental setup show this as a very promising avenue for further work.
© All rights reserved Araůjo et al. and/or their publisher
Quinn, Philip, Cockburn, Andy, Casiez, Géry, Roussel, Nicolas and Gutwin, Carl (2012): Exposing and understanding scrolling transfer functions. In: Proceedings of the 2012 ACM Symposium on User Interface Software and Technology 2012. pp. 341-350.
Scrolling is controlled through many forms of input devices, such as mouse wheels, trackpad gestures, arrow keys, and joysticks. Performance with these devices can be adjusted by introducing variable transfer functions to alter the range of expressible speed, precision, and sensitivity. However, existing transfer functions are typically "black boxes" bundled into proprietary operating systems and drivers. This presents three problems for researchers: (1) a lack of knowledge about the current state of the field; (2) a difficulty in replicating research that uses scrolling devices; and (3) a potential experimental confound when evaluating scrolling devices and techniques. These three problems are caused by gaps in researchers' knowledge about what device and movement factors are important for scrolling transfer functions, and about how existing devices and drivers use these factors. We fill these knowledge gaps with a framework of transfer function factors for scrolling, and a method for analysing proprietary transfer functions -- demonstrating how state of the art commercial devices accommodate some of the human control phenomena observed in prior studies.
© All rights reserved Quinn et al. and/or ACM Press
Roussel, Nicolas, Casiez, Géry, Aceituno, Jonathan and Vogel, Daniel (2012): Giving a hand to the eyes: leveraging input accuracy for subpixel interaction. In: Proceedings of the 2012 ACM Symposium on User Interface Software and Technology 2012. pp. 351-358.
We argue that the current practice of using integer positions for pointing events artificially constrains human precision capabilities. The high sensitivity of current input devices can be harnessed to enable precise direct manipulation ""in between"" pixels, called subpixel interaction. We provide detailed analysis of subpixel theory and implementation, including the critical component of revised control-display gain transfer functions. A prototype implementation is described with several illustrative examples. Guidelines for subpixel domain applicability are provided and an overview of required changes to operating systems and graphical user interface frameworks are discussed.
© All rights reserved Roussel et al. and/or ACM Press
Casiez, Géry, Roussel, Nicolas, Vanbelleghem, Romuald and Giraud, Frederic (2011): Surfpad: riding towards targets on a squeeze film effect. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems 2011. pp. 2491-2500.
We present Surfpad, a pointing facilitation technique that does not decrease target distance or increase target width in either control or display space. This new technique operates instead in the tactile domain by taking advantage of the ability to alter a touchpad's coefficient of friction by means of a squeeze film effect. We report on three experiments comparing Surfpad to the Semantic Pointing technique and constant control-display gain with and without distractor targets. Our results clearly show the limits of traditional target-aware control-display gain adaptation in the latter case, and the benefits of our tactile approach in both cases. Surfpad leads to a performance improvement close to 9% compared to unassisted pointing at small targets with no distractor. It is also robust to high distractor densities, keeping an average performance improvement of nearly 10% while Semantic Pointing can
© All rights reserved Casiez et al. and/or their publisher
Vogel, Daniel and Casiez, Géry (2011): Conté: multimodal input inspired by an artist's crayon. In: Proceedings of the 2011 ACM Symposium on User Interface Software and Technology 2011. pp. 357-366.
Conté is a small input device inspired by the way artists manipulate a real Conté crayon. By changing which corner, edge, end, or side is contacting the display, the operator can switch interaction modes using a single hand. Conté's rectangular prism shape enables both precise pen-like input and tangible handle interaction. Conté also has a natural compatibility with multi-touch input: it can be tucked in the palm to interleave same-hand touch input, or used to expand the vocabulary of bimanual touch. Inspired by informal interviews with artists, we catalogue Conté's characteristics, and use these to outline a design space. We describe a prototype device using common materials and simple electronics. With this device, we demonstrate interaction techniques in a test-bed drawing application. Finally, we discuss alternate hardware designs and future human factors research to study this new class of input.
© All rights reserved Vogel and Casiez and/or ACM Press
Casiez, Géry and Roussel, Nicolas (2011): No more bricolage!: methods and tools to characterize, replicate and compare pointing transfer functions. In: Proceedings of the 2011 ACM Symposium on User Interface Software and Technology 2011. pp. 603-614.
Transfer functions are the only pointing facilitation technique actually used in modern graphical interfaces involving the indirect control of an on-screen cursor. But despite their general use, very little is known about them. We present EchoMouse, a device we created to characterize the transfer functions of any system, and libpointing, a toolkit that we developed to replicate and compare the ones used by Windows, OS X and Xorg. We describe these functions and report on an experiment that compared the default one of the three systems. Our results show that these default functions improve performance up to 24% compared to a unitless constant CD gain. We also found significant differences between them, with the one from OS X improving performance for small target widths but reducing its performance up to 9% for larger ones compared to Windows and Xorg. These results notably suggest replacing the constant CD gain function commonly used by HCI researchers by the default function of the considered systems.
© All rights reserved Casiez and Roussel and/or ACM Press
Amberg, Michel, Giraud, Frederic, Semail, Betty, Olivo, Paolo, Casiez, Géry and Roussel, Nicolas (2011): STIMTAC: a tactile input device with programmable friction. In: Proceedings of the 2011 ACM Symposium on User Interface Software and Technology 2011. pp. 7-8.
We present the STIMTAC, a touchpad device that supports friction reduction. Contrary to traditional vibrotactile approaches, the STIMTAC provides information passively, acting as a texture display. It does not transfer energy to the user but modifies how energy is dissipated within the contact area by a user-initiated friction process. We report on the iterative process that led to the current hardware design and briefly describe the software framework that we are developing to illustrate its potential.
© All rights reserved Amberg et al. and/or ACM Press
Xu, Quan and Casiez, Géry (2010): Push-and-pull switching: window switching based on window overlapping. In: Proceedings of ACM CHI 2010 Conference on Human Factors in Computing Systems 2010. pp. 1335-1338.
We propose Push-and-Pull Switching, a window switching technique using window overlapping to implicitly define groups. Push-and-Pull Switching enables switching between groups and restacking the focused window to any position to change its group membership. The technique was evaluated in an experiment which found that Push-and-Pull Switching improves switching performance by more than 50% compared to other switching techniques in different scenarios. A longitudinal user study indicates that participants invoked this switching technique 15% of the time on single monitor displays and that they found it easy to understand and use.
© All rights reserved Xu and Casiez and/or their publisher
Martinet, Anthony, Casiez, Géry and Grisoni, Laurent (2010): The effect of DOF separation in 3D manipulation tasks with multi-touch displays. In: Proceedings of the 2010 ACM Symposium on Virtual Reality Software and Technology 2010. pp. 111-118.
Multi-touch displays represent a promising technology for the display and manipulation of data. While the manipulation of 2D data has been widely explored, 3D manipulation with multi-touch displays remains largely uncovered. Based on an analysis of the integration and separation of degrees of freedom, we propose a taxonomy for 3D manipulation techniques with multi-touch displays. Using that taxonomy, we introduce DS3 (Depth-Separated Screen Space), a new 3D manipulation technique based on the separation of translation and rotation. In a controlled experiment, we compare DS3 with Sticky Tools and Screen-Space. Results show that separating the control of translation and rotation significantly affects performance for 3D manipulation, with DS3 being at least 22% faster.
© All rights reserved Martinet et al. and/or ACM Press
Choumane, Ali, Casiez, Géry and Grisoni, Laurent (2010): Buttonless clicking: Intuitive select and pick-release through gesture analysis. In: Lok, Benjamin, Klinker, Gudrun and Nakatsu, Ryohei (eds.) IEEE Virtual Reality Conference, VR 2010 March 20-24, 2010, Waltham, Massachusetts, USA. pp. 67-70.
Vogel, Daniel, Cudmore, Matthew, Casiez, Géry, Balakrishnan, Ravin and Keliher, Liam (2009): Hand occlusion with tablet-sized direct pen input. In: Proceedings of ACM CHI 2009 Conference on Human Factors in Computing Systems 2009. pp. 557-566.
We present results from an experiment examining the area occluded by the hand when using a tablet-sized direct pen input device. Our results show that the pen, hand, and forearm can occlude up to 47% of a 12 inch display. The shape of the occluded area varies between participants due to differences in pen grip rather than simply anatomical differences. For the most part, individuals adopt a consistent posture for long and short selection tasks. Overall, many occluded pixels are located higher relative to the pen than previously thought. From the experimental data, a five-parameter scalable circle and pivoting rectangle geometric model is presented which captures the general shape of the occluded area relative to the pen position. This model fits the experimental data much better than the simple bounding box model often used implicitly by designers. The space of fitted parameters also serves to quantify the shape of occlusion. Finally, an initial design for a predictive version of the model is discussed.
© All rights reserved Vogel et al. and/or ACM Press
Sauvan, Jean-Baptiste, Lecuyer, Anatole, Lotte, Fabien and Casiez, Géry (2009): A performance model of selection techniques for p300-based brain-computer interfaces. In: Proceedings of ACM CHI 2009 Conference on Human Factors in Computing Systems 2009. pp. 2205-2208.
In this paper, we propose a model to predict the performance of selection techniques using Brain-Computer Interfaces based on P300 signals. This model is based on Markov theory and can compute both the time required to select a target and the number of visual flashes needed. We illustrate how to use this model with three different interaction techniques to select a target. A first experimental evaluation with three healthy participants shows a good match between the model and the experimental data.
© All rights reserved Sauvan et al. and/or ACM Press
Casiez, Géry and Vogel, Daniel (2008): The effect of spring stiffness and control gain with an elastic rate control pointing device. In: Proceedings of ACM CHI 2008 Conference on Human Factors in Computing Systems April 5-10, 2008. pp. 1709-1718.
Isometric and elastic devices are most compatible with a rate control mapping. However, the effect of elastic stiffness has not been thoroughly investigated nor its interaction with control gain. In a controlled experiment, these factors are investigated along with user feedback regarding ease-of-use and fatigue. The results reveal a U-shaped profile of control gain vs. movement time, with different profiles for different stiffness levels. Using the optimum control gain for each stiffness level, performance across stiffness levels were similar. However, users preferred lower stiffness and lower control gain levels due to increased controller displacement. Based on these results, design guidelines for elastic rate control devices are given.
© All rights reserved Casiez and Vogel and/or ACM Press
Casiez, Géry, Vogel, Daniel, Balakrishnan, Ravin and Cockburn, Andy (2008): The Impact of Control-Display Gain on User Performance in Pointing Tasks. In Human-Computer Interaction, 23 (3) pp. 215-250.
We theoretically and empirically examine the impact of control display (CD) gain on mouse pointing performance. Two techniques for modifying CD gain are considered: constant gain (CG) where CD gain is uniformly adjusted by a constant multiplier, and pointer acceleration (PA) where CD gain is adjusted using a nonuniform function depending on movement characteristics. Both CG and PA are evaluated at various levels of relationship between mouse and cursor movement: from low levels, which have a near one-to-one mapping, through to high levels that aggressively amplify mouse movement. We further derive a model predicting the modification in motor-space caused by pointer acceleration. Experiments are then conducted on a standard desktop display and on a very large high-resolution display, allowing us to measure performance in high index of difficulty tasks where the effect of clutching may be pronounced. The evaluation apparatus was designed to minimize device quantization effects and used accurate 3D motion tracking equipment to analyze users' limb movements. On both displays, and in both gain techniques, we found that low levels of CD gain had a marked negative effect on performance, largely because of increased clutching and maximum limb speeds. High gain levels had relatively little impact on performance, with only a slight increase in time when selecting very small targets at high levels of constant gain. On the standard desktop display, pointer acceleration resulted in 3.3% faster pointing than constant gain and up to 5.6% faster with small targets. This supported the theoretical prediction of motor-space modification but fell short of the theoretical potential, possibly because PA caused an increase in target overshooting. Both techniques were accurately modeled by Fitts' law in all gain settings except for when there was a significant amount of clutching. From our results, we derive a usable range of CD gain settings between thresholds of speed and accuracy given the capabilities of a pointing device, display, and the expected range of target widths and distances.
© All rights reserved Casiez et al. and/or Taylor and Francis
Hillaire, Sébastien, Lecuyer, Anatole, Cozot, Rémi and Casiez, Géry (2008): Using an Eye-Tracking System to Improve Camera Motions and Depth-of-Field Blur Effects in Virtual Environments. In: IEEE Virtual Reality Conference 2008 VR 2008 8-12 March, 2008, Reno, Nevada, USA. pp. 47-50.
Hillaire, Sébastien, Lecuyer, Anatole, Cozot, Rémi and Casiez, Géry (2008): Depth-of-Field Blur Effects for First-Person Navigation in Virtual Environments. In IEEE Computer Graphics and Applications, 28 (6) pp. 47-55.
Casiez, Géry, Vogel, Daniel, Pan, Qing and Chaillou, Christophe (2007): RubberEdge: reducing clutching by combining position and rate control with elastic feedback. In: Proceedings of the ACM Symposium on User Interface Software and Technology October 7-10, 2007, Newport, Rhode Island, USA. pp. 129-138.
Position control devices enable precise selection, but significant clutching degrades performance. Clutching can be reduced with high control-display gain or pointer acceleration, but there are human and device limits. Elastic rate control eliminates clutching completely, but can make precise selection difficult. We show that hybrid position-rate control can outperform position control by 20% when there is significant clutching, even when using pointer acceleration. Unlike previous work, our RubberEdge technique eliminates trajectory and velocity discontinuities. We derive predictive models for position control with clutching and hybrid control, and present a prototype RubberEdge position-rate control device including initial user feedback.
© All rights reserved Casiez et al. and/or ACM Press
Hillaire, Sébastien, Lecuyer, Anatole, Cozot, Rémi and Casiez, Géry (2007): Depth-of-field blur effects for first-person navigation in virtual environments. In: Majumder, Aditi, Hodges, Larry F., Cohen-Or, Daniel and Spencer, Stephen N. (eds.) VRST 2007 - Proceedings of the ACM Symposium on Virtual Reality Software and Technology November 5-7, 2007, Newport Beach, California, USA. pp. 203-206.
Casiez, Géry and Chaillou, Christophe (2005): Effects of DOF Separation on Elastic Devices for the Navigation in 3D Virtual Environments with Force Feedback. In: WHC 2005 - World Haptics Conference 18-20 March, 2005, Pisa, Italy. pp. 483-486.
Casiez, Géry, Plénacoste, Patricia and Chaillou, Christophe (2004): Does DOF Separation on Elastic Devices Improve User 3D Steering Task Performance?. In: Masoodian, Masood, Jones, Steve and Rogers, Bill (eds.) Computer Human Interaction 6th Asia Pacific Conference - APCHI 2004 June 29 - July 2, 2004, Rotorua, New Zealand. pp. 70-80.
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