Hand Occlusion on a Multi-Touch Tabletop

International audienceWe examine the shape of hand and forearm occlusion on a multi-touch table for different touch contact types and tasks. Individuals have characteristic occlusion shapes, but with commonalities across tasks, postures, and handedness. Based on this, we create templates for designers to justify occlusion-related decisions and we propose geometric models capturing the shape of occlusion. A model using diffused illumination captures performed well when augmented with a forearm rectangle, as did a modified circle and rectangle model with ellipse "fingers" suitable when only X-Y contact positions are available. Finally, we describe the corpus of detailed multi-touch input data we generated which is available to the community

1€ Filter: A Simple Speed-based Low-pass Filter for Noisy Input in Interactive Systems

International audienceThe 1€ filter ("one Euro filter") is a simple algorithm to filter noisy signals for high precision and responsiveness. It uses a first order low-pass filter with an adaptive cutoff frequency: at low speeds, a low cutoff stabilizes the signal by reducing jitter, but as speed increases, the cutoff is increased to reduce lag. The algorithm is easy to implement, uses very few resources, and with two easily understood parameters, it is easy to tune. In a comparison with other filters, the 1€ filter has less lag using a reference amount of jitter reduction

How low can you go? Human limits in small unidirectional mouse movements

International audienceComputer mouse sensors keep increasing in resolution. The smallest displacement they can detect gets smaller, but little is known on our ability to control such small movements. Small target acquisition has been previously tackled, but the findings do not apply to the problem of finding the useful resolution of a user with a mouse, which corresponds to the smallest displacement (s)he can reliably produce with that device. We detail this definition and provide an associated experimental protocol to measure it. We then report on the results of a study suggesting that high-end mice are not likely to be used to their full potential. We further comment on the different strategies used by participants to acheive best performance, and derive implications for user interfaces

Reliability of on-line visual feedback influences learning of continuous motor task of healthy young adults

A continuous task was used to determine how the reliability of on-line visual feedback during acquisition impacts motor learning. Participants performed a right hand pointing task of a repeated sequence with a visual cursor that was either reliable, moderately unreliable, or largely unreliable. Delayed retention tests were administered 24 h later, as well as intermanual transfer tests (performed with the left hand). A visuospatial transfer test was performed with the same targets’ sequence (same visuospatial configuration) while a motor transfer test was performed with the visual mirror of the targets’ sequence (same motor patterns). Results showed that pointing was slower and long-term learning disrupted in the largely unreliable visual cursor condition, compared with the reliable and moderately unreliable conditions. Also, analysis of transfers revealed classically better performance on visuospatial transfer than on motor transfer for the reliable condition. However, here we first show that such difference disappears when the cursor was moderately or largely unreliable. Interestingly, these results indicated a difference in the type of sequence coding, depending on the reliability of the on-line visual feedback. This recourse to mixed coding opens up interesting perspectives, as it is known to promote better learning of motor sequences

Direct and Indirect Multi-Touch Interaction on a Wall Display

National audienceMulti-touch wall displays allow to take advantage of co-located interaction (direct interaction) on very large surfaces. However interacting with content beyond arms' reach requires body movements, introducing fatigue and impacting performance. Interacting with distant content using a pointer can alleviate these problems but introduces legibility issues and loses the benefits of multi-touch interaction. We introduce WallPad, a widget designed to quickly access remote content on wall displays while addressing legibility issues and supporting direct multi-touch interaction. After briefly describing how we supported multi-touch interaction on a wall display, we present the WallPad widget and explain how it supports direct, indirect and de-localized direct interaction

Efficacité et robustesse aux distracteurs d'un retour tactile pour faciliter le pointage

International audienceSurfpad is a pointing facilitation technique that operates in the tactile domain by taking advantage of the ability to alter a touchpad's coefficient of friction. We report on two experiments comparing it 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 gain adaptation in the latter case, and the benefits of our tactile approach in both cases. Surfpad can lead to a performance improvement of up to 21% 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 degrade up to 100%.Surfpad est une technique de facilitation du pointage tirant parti de la possibilité de modifier le coefficient de friction d'un pavé tactile. Nous décrivons deux expériences comparant cette technique au pointage sémantique et à un gain control-display constant, avec et sans distracteurs. Nos résultats montrent les limites de l'adaptation de gain sensible aux cibles en présence de distracteurs et les avantages de notre approche tactile dans les deux cas. Le gain de temps permis par Surfpad face au pointage sans assistance peut aller jusqu'à 21% dans le cas de petites cibles sans distracteur. Notre technique est également robuste aux grandes densités de distracteurs, améliorant en moyenne les performances de près de 10% quand le pointage sémantique peut les dégrader jusqu'à 100%

RubberEdge: Reducing Clutching by Combining Position and Rate Control with Elastic Feedback

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.Comment: 10 page

Modeling On and Above a Stereoscopic Multitouch Display

International audienceWe present 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 developed on-and-above-the-surface interaction techniques based on asymmetric bimanual interaction for creating and editing 3D models in a stereoscopic environment. Our approach combines hand and nger tracking in the space on and above a multitouch 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 to leverage the bene t of both interaction spaces

Amélioration du Raycasting par utilisation de la sélection par proximité et du filtrage

Special issue : the best of IHM'2018International audienceRaycasting is the most common target pointing technique in virtual reality environments. However, performance on small and distant targets is impacted by the accuracy of the pointing device and the user's motor skills. Current pointing facilitation techniques are currently only applied in the context of the virtual hand, i.e. for targets within reach. We propose enhancements to Raycasting : filtering the ray, and adding a controllable cursor on the ray to select the nearest target. We describe a series of studies for the design of the visual feedforward, filtering technique, as well as a comparative study between different 3D pointing techniques. Our results show that highlighting the nearest target is one of the most efficient visual feedforward technique. We also show that filtering the ray reduces error rate in a drastic way. Finally we show the benefits of RayCursor compared to Raycasting and another technique from the literature.Raycasting est la technique de pointage de cible la plus courante dans les environnements de réalité virtuelle. Cependant, sa performance sur des cibles à la fois petites et distantes est affectée par la précision du dispositif de pointage et les capa-cités motrices de l'utilisateur. Les techniques actuelles de facilitation du pointage ne sont actuellement appliquées que dans le contexte de la main virtuelle, c'est-à-dire pour les cibles à portée de main. Nous proposons des améliorations au Raycasting : le fil-trage du rayon, et l'ajout d'un curseur contrôlable sur celui-ci pour sélectionner la cible la plus proche. Nous décrivons une série d'études pour la conception d'aides visuelles, la technique de filtrage, ainsi qu'une étude comparative entre différentes techniques de pointage 3D. Nos résultats montrent que la mise en évidence de la cible la plus proche est l'une des techniques les plus efficaces de rétroaction visuelle. Nous montrons éga-lement que le filtrage du rayon réduit le taux d'erreur de manière drastique. Enfin, nous montrons les avantages de RayCursor par rapport à Raycasting et à une autre technique de la littérature

TurboMouse: End-to-end Latency Compensation in Indirect Interaction

International audienceEnd-to-end latency corresponds to the temporal difference between a user input and the corresponding output from a system. It has been shown to degrade user performance in both direct and indirect interaction. If it can be reduced to some extend, latency can also be compensated through software compensation by trying to predict the future position of the cursor based on previous positions, velocities and accelerations. In this paper, we propose a hybrid hardware and software prediction technique specifically designed for partially compensating end-to-end latency in indirect pointing. We combine a computer mouse with a high frequency accelerometer to predict the future location of the pointer using Euler based equations