Authoring and Living Next-Generation Location-Based Experiences

Authoring location-based experiences involving multiple participants, collaborating or competing in both indoor and outdoor mixed realities, is extremely complex and bound to serious technical challenges. In this work, we present the first results of the MAGELLAN European project and how these greatly simplify this creative process using novel authoring, augmented reality (AR) and indoor geolocalisation techniques

The SOLAIRE Project: A Gaze-Contingent System to Facilitate Reading for Patients with Scotomatas

Reading is a major issue for visually impaired patients suffering from a blind area in the fovea. Current systems to facilitate reading do not really benet from recent advances in computer science, such as computer vision and augmented reality. On the SOLAIRE project (Système d'Optimisation de la Lecture par Asservissement de l'Image au Regard), we develop an augmented reality system to help patients to read more easily, resulting from a strong interaction between ophthalmologists and researchers in visual neuroscience and computer science. The main idea in this project is to control the display of the text read with the gaze, taking into account the specic characteristics of the scotoma for every individual. This report describes the system

Linguistic processes do not beat visuo-motor constraints, but they modulate where the eyes move regardless of word boundaries: Evidence against top-down word-based eye-movement control during reading

International audienceWhere readers move their eyes, while proceeding forward along lines of text, has long been assumed to be determined in a top-down word-based manner. According to this classical view, readers of alphabetic languages would invariably program their saccades towards the center of peripheral target words, as selected based on the (expected) needs of ongoing (word-identification) processing, and the variability in within-word landing positions would exclusively result from systematic and random errors. Here we put this predominant hypothesis to a strong test by estimating the respective influences of language-related variables (word frequency and word predictability) and lower-level visuo-motor factors (word length and saccadic launch-site distance to the beginning of words) on both word-skipping likelihood and within-word landing positions. Our eye-movement data were collected while forty participants read 316 pairs of sentences, that differed only by one word, the prime; this was either semantically related or unrelated to a following test word of variable frequency and length. We found that low-level visuo-motor variables largely predominated in determining which word would be fixated next, and where in a word the eye would land. In comparison, language-related variables only had tiny influences. Yet, linguistic variables affected both the likelihood of word skipping and within-word initial landing positions, all depending on the words’ length and how far on average the eye landed from the word boundaries, but pending the word could benefit from peripheral preview. These findings provide a strong case against the predominant word-based account of eye-movement guidance during reading, by showing that saccades are primarily driven by low-level visuo-motor processes, regardless of word boundaries, while being overall subject to subtle, one-off, language-based modulations. Our results also suggest that overall distributions of saccades’ landing positions, instead of truncated within-word landing-site distributions, should be used for a better understanding of eye-movement guidance during reading

Navisio: Towards an integrated reading aid system for low vision patients

International audienceWe propose the Navisio software as a new integrated system to help low vision patients read complex electronic documents (here, PDF files) with more comfort. Navisio aims at taking into account main psychophysical results on reading performance of visually impaired patients. To do this, we analyze what are the main factors in uencing reading performance, and review some existing reading aid systems, dealing with printed and electronic documents. Then, we show how Navisio allows to extend the capabilities of existing reading systems, focusing on the facilitation to navigate in complex documents, and on the highly customizable display. Navisio performance was evaluated against a standard CCTV magnifier tool, with 26 low vision patients. Two kinds of texts were proposed (simple and complex documents) elaborated from a standardised text database. Results show a clear advantage of Navisio in terms of reading speed and comfort. Navisio is intended to evolve: we discuss how it could be extended to any scanned document, thanks to recent computer vision approaches in document layout analysis. Further challenging perspectives are also mentioned

Human Retinotopic Mapping Using fMRI

We present in this report a new method for the retinotopic mapping of the human visual cortex using fMRI. This fast method allow s to delineate any human's occipital retinotopic visual areas after 30 minutes in an MR scanner. Based on the known retinotopic properties o f the visual cortex and on the procedures described in the literature, we first detail the experimental protocol we used. We then present th e functional data analysis we perform to get the retinotopic angular maps. The algorithm to get a model of the cortical surface from the ana tomical MR image is also rapidly presented. We then show the retinotopic maps projected on the latter model and compare them with the litera ture. Lastly, we present the choices we made to delineate these areas and extract regions of interest that can be used for further studying the human visual cortical system

Selective modulation of visual sensitivity during fixation

During periods of steady fixation, we make small amplitude ocular movements, termed microsaccades, at a rate of 1-2 every second. Early studies provided evidence that visual sensitivity is reduced during microsaccades - akin to the well-established suppression associated with larger saccades. However, the results of more recent work suggest that microsaccades may alter retinal input in a manner that enhances visual sensitivity to some stimuli. Here, we parametrically varied the spatial frequency of a stimulus during a detection task and tracked contrast sensitivity as a function of time relative to microsaccades. Our data reveal two distinct modulations of sensitivity: suppression during the eye movement itself, and facilitation after the eye has stopped moving. The magnitude of suppression and facilitation of visual sensitivity is related to the spatial content of the stimulus: suppression is greatest for low spatial frequencies while sensitivity is enhanced most for stimuli of 1-2 c/deg, spatial frequencies at which we are already most sensitive in the absence of eye movements. We present a model where the tuning of suppression and facilitation is explained by delayed lateral inhibition between spatial frequency channels. Our data show that eye movements actively modulate visual sensitivity even during fixation: the detectability of images at different spatial scales can be increased or decreased depending on when the image occurs relative to a microsaccade

Désorganisation fonctionnelle des systèmes oculomoteur et visuo-attentionnnel chez les patients basse vision (- Approche psychophysique-)

La présence d'un scotome maculaire oblige les patients à utiliser la vision excentrée ce qui provoque une difficulté à coordonner les systèmes oculomoteur et visuo-attentionnel. La lecture devient alors une des plaintes majeures chez ces patients, et les processus impliqués dans la baisse des performances de lecture restent mal connus. Dans la plupart des cas, le patient développe une ou plusieurs zones de la rétine excentrée dites préférentielles, et dénommées couramment PRLs. Nous nous proposons ici d'utiliser une approche psychophysique afin d'étudier les processus de la lecture en vision excentrée. Nous avons tout d'abord élaboré un test de lecture francophone informatisé suivant les principes des MNRead Acuity Charts afin de pouvoir évaluer la vitesse maximale de lecture chez des patients porteurs de scotomes centraux binoculaires dont l'atteinte avait été mesurée à l'aide d'un micropérimètre MP-1. Deux analyses utilisant des modèles statistiques à effets mixtes nous ont permis de mettre en évidence des prédicteurs efficaces de la vitesse maximale de lecture: 1) l'espace interligne; 2) le type de DMLA ; 3) la surface du scot; 4) la distance entre la PRL de fixation et la fovéa; 5) le statut du cristallin. Puis, nous nous sommes intéressés aux stratégies de lecture déployées par les patients. L'analyse de la distribution verticale des fixations enregistrées pendant la lecture nous a permis de mettre en évidence que dans 97% des cas, les patients utilisent une zone préférentielle de la rétine unique dans le plan vertical.Ces résultats présentent des intérêts théoriques et pratiques dans la création de nouveaux supports visuels et techniques de réadaptation.Patients with central field loss (CFL) have to use eccentric vision and complain particularly about reading. The purpose of this thesis is to investigate reading processes in those patients using psychophysical tools. First, we investigated predictors of reading performances. We developed a French computerized version of the MNRead Acuity Charts to assess Maximum Reading Speed in patients with binocular scotomas, measured with the microperimeter MP-1. Two distinct analyses using mixed effects models allowed us to estimate the influence of predictors of Maximum Reading Speed: 1) interline spacing; 2) AMD type; 3) scotoma size; 4) distance between fixation PRL and fovea; 5) lens status. Then, we investigated oculomotor patterns of patients during sentence reading. Analysing the vertical distribution of fixations lead us to the conclusion that in most cases (97%), patients use a single eccentric preferred retinal locus (PRL) in the vertical meridian during reading. One potential goal of these studies is to find some ways to enhance text display and improve visual readaptation.AIX-MARSEILLE2-Bib.electronique (130559901) / SudocSudocFranceF

A Model of Optimal Oculomotor Strategies in Reading for Normal and Damaged Visual Fields

ISBN : 978-2-9532965-0-1We present an ideal observer analysis of single word reading in normal readers and central scotoma patients. Using this technique we are able to predict the spatio-temporal pattern of saccades in terms of pixels. This enables us to contrast theories that are impossible to compare using the traditional letter-slot approaches to modelling reading

Second-Order Nonlinear Optical Properties of Multiaddressable Indolinooxazolidine Derivatives: Joint Computational and Hyper-Rayleigh Scattering Investigations

The linear and nonlinear optical (NLO) properties of two indolinooxazolidine derivatives acting as multiaddressable switches are reported. The second-order hyperpolarizability contrasts upon commutation between their closed and open forms are characterized using hyper-Rayleigh scattering (HRS) measurements, and rationalized by means of density functional theory and post Hartree–Fock ab initio calculations. It is evidenced that the addition of a withdrawing substituent on the indolinic subunit leads to a more effective photoinduced charge transfer while decreasing the transition energy of the S0 → S1 transition, which induces a significant enhancement of the HRS response of the open form. This substitution is however detrimental to the NLO contrast, due to the concomitant increase of the HRS response of the closed form