Rake Cursor: Improving Pointing Performance with Concurrent Input Channels

International audienceWe investigate the use of two concurrent input channels to perform a pointing task. The first channel is the traditional mouse input device whereas the second one is the gaze position. The rake cursor interaction technique combines a grid of cursors controlled by the mouse and the selection of the active cursor by the gaze. A controlled experiment shows that rake cursor pointing drastically outperforms mouse-only pointing and also significantly outperforms the state of the art of pointing techniques mixing gaze and mouse input. A theory explaining the improvement is proposed: the global difficulty of a task is split between those two channels, and the sub-tasks could partly be performed concurrently

Pseudo-Weight: Making Tabletop Interaction with Virtual Objects More Tangible

International audienceIn this paper we show that virtual objects manipulated on a tabletop interaction device can be augmented to provide the illusion they have a weight. This weight offers a supplemental channel to provide information about graphical objects without cluttering the visual display. To create such a pseudo-weight illusion on a passive device, the pressure applied with the fingers during the interaction has to be captured. We show that this pressure can be estimated without hardware modification on some touch sensitive tabletop setups (e.g., MERL's DiamondTouch). Two controlled experiments show that pseudo-weight is perceived effectively. The first one demonstrates that users, without training and without previous knowledge of the system, can accurately rank virtual objects according to their pseudo-weights, provided they are sufficiently distinct. The second controlled experiment investigates more formally the relation between the pseudo-weight and the actual perception of the users

Two Touch System Latency Estimators: High Accuracy and Low Overhead

International audienceThe end-to-end latency of interactive systems is well known to degrade user's performance. Touch systems exhibit notable amount of latencies, but it is seldom characterized, probably because latency estimation is a difficult and time consuming undertaking. In this paper, we introduce two novel approaches to estimate the latency of touch systems. Both approaches require an operator to slide a finger on the touch surface, and provide automatic processing of the recorded data. The High Accuracy (HA) approach requires an external camera and careful calibration, but provides a large sample set of accurate latency estimations. The Low Overhead (LO) approach, while not offering as much accuracy as the HA approach, does not require any additional equipment and is implemented in a few lines of code. In a set of experiments, we show that the HA approach can generate a highly detailed picture of the latency distribution of the system, and that the LO approach provides average latency estimates no further than 4~ms from the HA estimate

A Novel Taxonomy for Gestural Interaction Techniques Based on Accelerometers

Session: Multimodal interfacesInternational audienceA large variety of gestural interaction techniques based on accelerometers is now available. In this article, we propose a new taxonomic space as a systematic structure for supporting the comparative analysis of these techniques as well as for designing new ones. An interaction technique is plotted as a point in a space where the vertical axis denotes the semantic coverage of the techniques, and the horizontal axis expresses the physical actions users are engaged in, i.e. the lexicon. In addition, syntactic modifiers are used to express the interpretation process of input tokens into semantics, as well as pragmatic modifiers to make explicit the level of indirection between users' actions and system responses. To demonstrate the coverage of the taxonomy, we have classified 25 interaction techniques based on accelerometers. The analysis of the design space per se reveals directions for future research

Evaluation in-situ d'une approche "What if" pour l'eco-feedback

International audienceDecreasing electricity consumption is a major challenge of our society. Eco-feedback methods allow users to get information about their electricity consumption to reduce it. However it is still difficult to determine what are the actions that impact the consumption in practice. In this paper we suggest to apply a What if approach to eco-feedback in a household context. We deploy the Activelec system in personal housings, which allows to apply virtual modifications in appliances usage and to evaluate the savings realized. The results of our experimentation show that participants appreciated the interaction method based on the What if. It allowed them to find and to evaluate efficient modifications in their appliances usage, and several have been applied in practice by the participants. This experimentation shows that the What if paradigm is a potential way for eco-feedback technologies.Réduire la consommation d’électricité est un enjeu majeur de notre société. Les méthodes eco-feedback permettent aux utilisateurs d’obtenir un retour sur leur consommation d’électricité afin de la diminuer. Toutefois, il est toujours difficile de déterminer concrètement quelles actions impactent la consommation. Dans cet article, nous proposons d’appliquer une méthode What if à l’eco-feedback en contexte domestique. Nous déployons le système Activelec dans des logements personnels, qui permet d’appliquer des changements virtuels dans l’utilisation des appareils et d’évaluer les économies réalisées. Les résultats de notre expérimentation montrent que les participants ont apprécié la méthode d’interaction basée sur le What if. Celle-ci leur a permis de trouver et d’évaluer des modifications efficaces dans l’utilisation de leurs appareils, et certaines ont été appliquées en pratique par les participants. Cette expérimentation montre que le paradigme What if est une piste potentielle pour les technologies eco-feedback

Activelec: an Interaction-Based Visualization System to Analyze Household Electricity Consumption

International audienceEveryone can now record and explore the evolution over time of his/her personal household electricity consumption. However understanding what links this data to our behavior remains a challenge. In this paper, we present a visualization tool based on the direct manipulation, by the users, of their behavior. Users can select and modify their actions over time, evaluating the results on the data with the visualization. We also conduct a user study, showing that our method allows users to understand the links between actions and data, and to use this knowledge in order to test and evaluate changes in their behavior

Data Science

International audienceLa data science, ou science des données, est la discipline qui traite de la collecte, de la préparation, de la gestion, de l'analyse, de l'interprétation et de la visualisation de grands ensembles de données complexes. Elle n'est pas seulement concernée par les outils et les méthodes pour obtenir, gérer et analyser les données ; elle consiste aussi à en extraire de la valeur et de la connaissance. Cet ouvrage présente les fondements scientifiques et les composantes essentielles de la science des données, à un niveau accessible aux étudiants de master et aux élèves ingénieurs. Notre souci a été de proposer un exposé cohérent reliant la théorie aux algorithmes développés dans ces domaines. Il s'adresse aux chercheurs et ingénieurs qui abordent les problématiques liées à la science des données, aux data scientists de PME qui utilisent en profondeur les outils d'apprentissage, mais aussi aux étudiants de master, doctorants ou encore futurs ingénieurs qui souhaitent un ouvrage de référence en data science. À qui s'adresse ce livre ? • Aux développeurs, statisticiens, étudiants et chefs de projets ayant à résoudre des problèmes de data science. • Aux data scientists, mais aussi à toute personne curieuse d'avoir une vue d'ensemble de l'état de l'art du machine learning

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3~PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron candidates. The potential to search for hadronic PeVatrons with the Cherenkov Telescope Array (CTA) is assessed. The focus is on the usage of very high energy $\gamma$-ray spectral signatures for the identification of PeVatrons. Assuming that SNRs can accelerate CRs up to knee energies, the number of Galactic SNRs which can be identified as PeVatrons with CTA is estimated within a model for the evolution of SNRs. Additionally, the potential of a follow-up observation strategy under moonlight conditions for PeVatron searches is investigated. Statistical methods for the identification of PeVatrons are introduced, and realistic Monte--Carlo simulations of the response of the CTA observatory to the emission spectra from hadronic PeVatrons are performed. Based on simulations of a simplified model for the evolution for SNRs, the detection of a $\gamma$-ray signal from in average 9 Galactic PeVatron SNRs is expected to result from the scan of the Galactic plane with CTA after 10 hours of exposure. CTA is also shown to have excellent potential to confirm these sources as PeVatrons in deep observations with $\mathcal{O}(100)$ hours of exposure per source.Comment: 34 pages, 16 figures, Accepted for publication in Astroparticle Physic

The 2010 very high energy gamma-ray flare & 10 years of multi-wavelength observations of M 87

Abridged: The giant radio galaxy M 87 with its proximity, famous jet, and very massive black hole provides a unique opportunity to investigate the origin of very high energy (VHE; E>100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of super-massive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (~day), peak fluxes (Phi(>0.35 TeV) ~= (1-3) x 10^-11 ph cm^-2 s^-1), and VHE spectra. 43 GHz VLBA radio observations of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken ~3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core. The long-term (2001-2010) multi-wavelength light curve of M 87, spanning from radio to VHE and including data from HST, LT, VLA and EVN, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified.Comment: 19 pages, 5 figures; Corresponding authors: M. Raue, L. Stawarz, D. Mazin, P. Colin, C. M. Hui, M. Beilicke; Fig. 1 lightcurve data available online: http://www.desy.de/~mraue/m87