Papers by Christophe Chaillou
This article presents the technical principles and a set of applications for a new ground-based t... more This article presents the technical principles and a set of applications for a new ground-based three degrees of freedom haptic device. The DigiHaptic can be used in isometric or isotonic mode with force feedback. It is a new and original approach to object manipulation in virtual worlds using degrees of freedom decoupling. The process which led us to create the DigiHaptic was based on a changed perspective regarding object manipulation in virtual reality, which required reconsideration of the interaction between the user and virtual reality. Leading edge research has now moved beyond the mere imitation of reality and its everyday gestures and is progressing on to the mapping of virtual worlds using reference marks in Cartesian co-ordinates.
... author = {Jérémie Dequidt and Laurent Grisoni and Christophe Chaillou}, title = {Solute trans... more ... author = {Jérémie Dequidt and Laurent Grisoni and Christophe Chaillou}, title = {Solute transport in porous media with equilibrium and non-equilibrium multiple-site adsorption ... Such simulation is combined with (obviously non-synchronous) network information. ...
This article presents a classification of and comparison between isotonic, isometric and elastic ... more This article presents a classification of and comparison between isotonic, isometric and elastic devices. It then introduces the DigiHaptic, a new three degrees of freedom multi-finger force feedback device, and its place in the device classification is proposed. Two notable features of the DigiHaptic are the decoupling of the degrees of freedom and the correlation between fingers and objects movements. Finally two force feedback solutions using the DigiHaptic in elastic mode are proposed for rate control in open and closed workspaces.
In this paper, we show a method to interact with physically-based environments in a way which gua... more In this paper, we show a method to interact with physically-based environments in a way which guarantee their integrity whatever the mechanical properties of the virtual interaction tool and the control device. It consists in an extension of the god-object concept. The interaction tools are modeled as physical bodies which tend to reach, if possible, the position maintained by the user. Their behavior is computed via the dynamic laws of motion by the simulation engine, as the other bodies in the scene. The cases of articulated rigid bodies and deformable bodies are studied. This mechanism also provides a unified framework which allows the control of virtual objects via devices providing force feedback or not. Finally, some applications including virtual surgery are shown to illustrate the effectiveness of the approach.
Biomedical Engineering, 1995
The practice of laser photocoagulation plays a major role in the ocular therapy, but the persiste... more The practice of laser photocoagulation plays a major role in the ocular therapy, but the persistence of many postoperative complications denotes genuine difficulty in mastering the technique. The authors present a device which, thanks to the use of simulation, enables actual practice to be dissociated from apprenticeship. While complying with the constraints of realism with regard to habitual conditions of laser use, the device offers access to a wide variety of clinical situations. The apparatus is built around the traditional instrument. A virtual image of the fundus is produced in real time from the sensors which detect the actual gestures used. The calculations make use of textured geometrical models. Digitized color photographs are organized to form a database which reflects the diversity of pigmentations and pathologies. A software interface has been developed to facilitate the use of the device. The prototype is operated using a PC-compatible computer; it displays the images at the rate of at least seven per second on a miniature CGA screen incorporated in the slit-lamp. It is currently being validated for clinical applications. Above and beyond apprenticeship in laser photocoagulation, its potential applications extend to the entire field of ophthalmogical symptomatology and, more broadly, to the simulation of any examination conducted with the help of binocular or endoscopic optics.
Wscg, Feb 5, 2001
Our work is centered on the use of implicit surfaces in interactive applications (at least 10 fra... more Our work is centered on the use of implicit surfaces in interactive applications (at least 10 frames per sec) running on high-end consumer architecture (modeling, simulation, deformable body animation, games). We focus on the Marching Cubes algorithm that we tried to implement in an optimized way. We restrict our work to blended iso-surfaces generated by skeletons, since this kind of implicit surfaces is the most handy to use for animations. Our implementation optimizations deal with the following features: simplifying the field function, accelerating its evaluation for each point (voxel-based technique), generating automatically the triangles for any case of the Marching Cubes. Another point we have considered concerns tesselation ambiguities often resulting in holes appearing in the surface. We have coded a library which is very easy to use and can be downloaded freely. All these optimizations allow us to sample implicit surfaces composed of 200 points in 45 ms on a 450 MHz Pentium II Xeon.
Dans cet article, nous proposons une méthode complète de traitement de collisions. Elle est const... more Dans cet article, nous proposons une méthode complète de traitement de collisions. Elle est constituée de différentesétapes qui permettent de détecter de plus en plus finement les collisions entre objets rigides convexes. La dernièreétape fournit des informations nécessairesà la génération d'une force de pénalités. Ce framework est compatible avec des objets autonomes (objets capables de gèrer leur propre comportement). Mots-clés : Objets rigides convexes, détection de collision, distance d'interpénétration, forces de pénalités.
Virtual Reality, 1999
Abstrac[: tn this paper, we present a three-dimensional user interface for synchronous co-operati... more Abstrac[: tn this paper, we present a three-dimensional user interface for synchronous co-operative work, Spin, which has been designed for multi-user synchronous real-time applications to be used in, for example, meetings and learning situations. Spin is based on a new metaphor of virtual workspace. We have designed an interface, for an office environment, which recreates the three-dimensional elements needed during a meeting and increases the user's scope of interaction. In order to accomplish these objectives, animation and three-dimensional interaction in real time are used to enhance the feeling of collaboration within the three-dimensional workspace. Spin is designed to maintain a maximum amount of information visible. The workspace is created using artificial geometry -as opposed to true three-dimensional geometryand spatial distortion, a technique that allows all documents and information to be displayed simultaneously while centring the user's focus of attention. Users interact with each other via their respective clones, which are three-dimensional representations displayed in each user's interface, and are animated with user action on shared documents. An appropriate object manipulation system (direct manipulation, 3D devices and specific interaction metaphors) is used to point out and manipulate 3D documents.
We present here a new three degrees of freedom (DOF) haptic device called DigiHaptic. Contrarily ... more We present here a new three degrees of freedom (DOF) haptic device called DigiHaptic. Contrarily to existing devices where the DOF are gathered into one end-effector, our device proposes a novel interaction concept that consists of the separation of the degrees of freedom in an intuitive way to three fingers. Its use in applications such as objects manipulation and navigation with force feedback are illustrated.
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Papers by Christophe Chaillou