Laure Leroy

Visual Fatigue Reduction for Immersive Stereoscopic Displays by Disparity, Content, and Focus-Point Adapted Blur

As stereoscopic devices become widely used (immersion-based working environments, stereoscopically viewed movies, autostereoscopic screens, etc), exposure to stereoscopic images can become lengthy, and some eyestrain can set in. We propose a method for reducing eyestrain induced by stereoscopic vision. After reviewing sources of eyestrain linked to stereoscopic vision, we will focus on one of these sources: images with high-frequency contents associated with large disparities. We will put forward an algorithm for removing irritating high frequencies in high disparity zones (i.e., for virtual objects appearing far from the real screen level). We will elaborate on our testing protocol to establish that our processing reduces eyestrain caused by stereoscopic vision, both objectively and subjectively. We will subsequently quantify the positive effects of our algorithm on the relief of eyestrain. As our processing alters the visual quality of the virtual world, we propose a new adaptation of our method to remove this drawback by coupling an eye tracking to our original processing to keep visual quality on the focus point.

Real-time adaptive blur for reducing eye strain in stereoscopic displays

Stereoscopic devices are widely used (immersion-based working environments, stereoscopically-viewed movies, auto-stereoscopic screens). In some instances, exposure to stereoscopic immersion techniques can be lengthy, and so eye strain sets in. We propose a method for reducing eye strain induced by stereoscopic vision. After reviewing sources of eye strain linked to stereoscopic vision, we focus on one of these sources: images with high frequency content associated with large disparities. We put forward an algorithm for removing the irritating high frequencies in high horizontal disparity zones (i.e., for virtual objects appearing far from the real screen level). We elaborate on our testing protocol to establish that our image processing method reduces eye strain caused by stereoscopic vision, both objectively and subjectively. We subsequently quantify the positive effects of our algorithm on the relief of eye strain and discuss further research perspectives.

Experiments on shape perception in stereoscopic displays

Stereoscopic displays are increasingly used for computer-aided design. The aim is to make virtual prototypes to avoid building real ones, so that time, money and raw materials are saved. But do we really know whether virtual displays render the objects in a realistic way to potential users? In this study, we have performed several experiments in which we compare two virtual shapes to their equivalent in the real world, each of these aiming at a specific issue by a comparison: First, we performed some perception tests to evaluate the importance of head tracking to evaluate if it is better to concentrate our efforts on stereoscopic vision; Second, we have studied the effects of interpupillary distance; Third, we studied the effects of the position of the main object in comparison with the screen. Two different tests are used, the first one using a well-known shape (a sphere) and the second one using an irregular shape but with almost the same colour and dimension. These two tests allow us to determine if symmetry is important in their perception. We show that head tracking has a more important effect on shape perception than stereoscopic vision, especially on depth perception because the subject is able to move around the scene. The study also shows that an object between the subject and the screen is perceived better than an object which is on the screen, even if the latter is better for the eye strain.

AGATHE: A tool for personalized rehabilitation of cognitive functions

Virtual Reality has recognized assets to address some cognitive rehabilitation issues. The purpose of this poster is to present an overview of the design of AGATHE, a tool for personalized rehabilitation of cognitive functions based on simulated Basic and Instrumental Activities of Daily Living (sBADL and sIADL).

Real time comfort enhancement in stereoscopic displays by disparity and content-adapted blur

Stereoscopic devices become widely used (immersion-based working environments, stereoscopically viewed movies, auto-stereoscopic screens…). In some instances, exposure to stereoscopic immersion techniques can be lengthy, and eyestrain sets in. We propose a method for reducing eyestrain induced by stereoscopic vision. After reviewing sources of eyestrain linked to stereoscopic vision, we will focus on one of these sources: images with high frequencies contents associated with large disparities. We will put forward an algorithm for removing the irritating high frequencies in high disparity zones (i.e. for virtual objects appearing far from the real screen level). We will elaborate on our testing protocol to establish that our processing reduces eyestrain caused by stereoscopic vision, both objectively and subjectively. We will subsequently quantify the positive effects of our algorithm on the relief of eyestrain.

Development of a String-Based Haptic Interface by Using a Hybrid Control Approach

String-based interfaces are promising to provide the force feedback for the operator of a virtual environment. However their performance is affected by some problems like instability, inertia and response lag, especially in the large environments. A hybrid position/force control method is presented in this paper. This approach is experimented on an interface with two actuators and force feedback is tested on different virtual objects. It is shown that the stability and transparency of the interface are increased

Improving shape perception in virtual reality systems using toed-in cameras

Nowadays, actual stereoscopic 3D renderers use two cameras to render images to the screen. These two cameras have parallel optical axis. It is well know that if cameras converge, then it produces distortions called vertical parallaxes. These distortions are supposed to stress visual system, but we do not know the effect on perception. In this article, we will test if these vertical parallaxes can improve shape perception. We found out that vertical parallaxes does improve shape perception, but the effect is decreased when the object is far from the user because when the cameras converge far away it get closer to a parallel configuration.

Rééducation personnalisée des fonctions cognitives via des activités de vie quotidienne simulées (sAVQ)

Objectif.– Étudier les troubles cognitifs présentés suite à un arrêt cardiaque extra-hospitalier. Matériel et patients.– Étude rétrospective et prospective d’une cohorte de 49 patients adultes (35 hommes, 14 femmes), d’un âge moyen de 43 ans (SD : 13,3), suivie dans un service de MPR à orientation neurologique. Méthode.–Évaluation neuropsychologique précise de l’ensemble des fonctions cognitives à un délai moyen de 13,8 mois de l’arrêt cardiaque. Étude longitudinale de 14 patients réévalués en moyenne 25 mois après le premier bilan. Résultats.– Le premier bilan neuropsychologique met en évidence des tableaux hétérogènes. Des troubles attentionnels et dysexécutifs sont constatés chez plus de 90 % des patients. 80 % des patients présentent une altération, modérée à sévère, de la mémoire antérograde. Même si une atteinte du stockage est observée chez 40 % des patients, les troubles mnésiques sont le plus souvent majorés par les troubles attentionnels et dysexécutifs ou imputables à ces derniers. La mémoire rétrograde et les fonctions instrumentales (langage, praxies, gnosies) sont perturbées chez environ 50 % des patients. Une nouvelle évaluation montre des progrès significatifs chez la plupart des patients (13 sur 14), même si des troubles persistent. Discussion.– Le tableau classique du syndrome amnésique isolé n’est pas retrouvé. Tous les troubles objectivés lors du premier bilan neuropsychologique sont rapportés dans la littérature mais notre population présente des troubles plus sévères et plus fréquents. Dans la littérature, la fréquence des troubles semble variable, dépendante des critères d’inclusion, de la sensibilité des tests utilisés et du délai entre l’arrêt cardiaque et l’évaluation neuropsychologique. Les progrès importants mis en évidence lors des réévaluations sont sans doute en partie liés à une récupération spontanée mais également en rapport avec la rééducation, nous amenant à préconiser une prise en charge adaptée aux difficultés cognitives présentées par cette population particulière. Pour en savoir plus Moulaert V, Verbunt J, Van Heugten C, Wade D. Cognitive impairments in survivors of out-of-hospital cardiac arrest: a systematic review. Resuscitation 2009;80:297–305. Peskine A, Rosso C, Picq C, Caron E, Pradat-Diehl P. Neurological sequelae after cerebral anoxia. Brain Injury 2010;24:755–61.