Thérapie par réalité virtuelle

La thérapie par réalité virtuelle consiste en l'utilisation de plateformes immersives (visiocasques, ordinateur, traqueur de mouvement, etc.) et d'environnements virtuels créés par ordinateur pour traiter des individus souffrant de maladies, de troubles physiques ou de troubles mentaux. Avec la production en masse de visiocasque depuis 2012 (date de la sortie des premiers Oculus) et autres équipement immersifs de réalité virtuelle permettant à l'utilisateur d'interagir en temps réel avec des environnements créés par ordinateur, de nombreux jeux vidéo immersifs sur ordinateur PC et consoles ont été distribués largement sur le marché. Les joueurs peuvent ainsi impliquer leurs sens de manière plus immersive dans une expérience de jeu. En dehors de l'univers ludique, le monde scientifique et médical a su tirer parti de cette confusion entre monde réel et virtuel qu’est capable d’induire un système informatique de pointe, ceci à des fins thérapeutiques. L’adjectif thérapeutique est à pr

Simulating interactions with virtual characters for the treatment of social phobia

Helena Stephanie Grillon Le Gallennec

Virtual Reality (VR) has nowadays become a very useful tool for therapists in the treatment of phobias. Indeed, it allows the simulation of scenarios which are difficult to reproduce in real life. It also allows for a situation to be repeated as much as one wants. Moreover, it allows for a complete control over the situation. The simulation can be stopped if the patient cannot handle it. It can also be tweaked for gradual exposure. Virtual Reality Exposure Therapy (VRET) has proven to be efficient in the context of phobias such as acrophobia or the fear of flying. Social phobia, however, are much harder to deal with. Indeed, as humans, we are experts in human representations and behaviors; it makes it much harder to obtain credible and immersive environments. In this thesis, we describe a set of tools and applications which we have developed to be used in VRET of social phobia and agoraphobia with crowds. We first describe how we create different scenarios for VRET of social phobia. We then expose the application we have developed which allows for elaborate interactions between a user and virtual characters. In particular, we have designed and implemented a software which allows for virtual characters to change behavior depending on the user's eye contact behavior. It allows them to seem interested when being looked at and distracted when not. We then describe the model we have implemented to simulate gaze attention behaviors for crowds of virtual characters. This consists of a method that automatically detects where and when each virtual character in a crowd should look. Secondly, it consists of a dedicated gaze Inverse Kinematics (IK) solver in order for the virtual characters to satisfy the constraints defined by the automatically detected points to be looked at. This allows for the characters to perform the looking motion in a natural and human like way. We then describe the architecture we have developed to combine the work we have done in the domain of social phobia and this model of attention behaviors for crowd characters. We thus use our model of looking behaviors to allow for crowd characters to look at each other. We also use eye-tracking and optical motion capture to determine where a user is looking in a CAVE environment. The virtual characters then respond by either looking at the user, looking at what the user is looking at, or looking at other characters in the crowd. We thus obtain an immersive and interactive environment for VRET in the domain of agoraphobia with crowds. The third part of this thesis describes various experiments we have conducted in order to validate our applications. Our first study consists of using VR in a head-mounted display (HMD) for the treatment of social phobia. In this study, we also use eye-tracking in order to analyze eye contact avoidance behaviors before and after therapy. We then discuss the use of eye-tracking as a tool to help assess and diagnose social phobia. Since eye contact avoidance behaviors are frequent in people suffering from such phobias, eye-tracking can certainly be a helpful tool. We describe an experiment in which we tested eye-tracking as a diagnosis and assessment tool on a phobic population and on a control group. We also describe an experiment to evaluate the potential of our proposed interaction loop in the context of social phobia. Finally, we describe the experiment we have conducted to evaluate our application in the context of agoraphobia with crowds.

EPFL2009

Rendering massive real-time crowds

Pablo Stanislaw De Heras Ciechomski

This thesis presents how to visualize a large crowd of virtual human characters in real time on a standard issue personal computer. The virtual humans are distributed into rendering fidelities such that the humans closer to the viewer are detailed and expressive while the further away they are, the less detailed they become. Fidelity partitioning starts with fully dynamic and geometric humans, meaning they can perform a full suit of animations even computed on-demand. Dynamic geometry is followed by static geometry such that a constrained set of animations can be achieved while the last and farthest detail level from the viewer is image-based and static. Various rendering accelerations applicable to each fidelity are used and compared, such as caching schemes, levels-of-detail, shaders and state sorting. Memory usage and artistic workload is reduced using template humans that are instantiated with individual varieties in animation, clothing, facial appearance and color combinations. An innovative constraining method for randomized colors is presented. With the opportunity of rendering large crowds, emerges the need for novel interaction methods such as the CrowdBrush, an intuitive spraycan interface for crowds. In the area of virtual therapy, individual human picking is presented using the GazeMap. Several other applications are shown to present the versatility and flexibility of the crowd rendering engine.

EPFL2006

Coding gaze tracking data with chromatic gradients for VR exposure therapy

Pablo Stanislaw De Heras Ciechomski, Helena Stephanie Grillon Le Gallennec, Bruno Herbelin, Daniel Thalmann

This article presents a simple and intuitive way to represent the eye-tracking data gathered during immersive virtual reality exposure therapy sessions. Eye-tracking technology can be used to observe gaze avoidance behaviors to provide cognitive and behavioral therapists with valuable information on the severity of a phobic disorder. However, basic eye-tracking systems only supply 2D gaze point coordinates on the recorded video images of the subject’s view. The use of eye-tracking during virtual reality sessions allows to directly associate the gaze behavior to the 3D environment. The gaze-map color coding presented here uses a color picking technique and a specific data representation which provides precise visual gaze information per 3D object. This article presents our technological solution and its relevance for therapeutic needs, as well as the experiments performed to demonstrate its usability in a medical context. Results show that the gaze-map technique is fully compatible with different VR exposure systems and provides clinically meaningful data.

2007

Simulating interactions with virtual characters for the treatment of social phobia

Helena Stephanie Grillon Le Gallennec

EPFL2009