Publications by Ronan Boulic | EPFL Graph Search

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Following limb loss, patients usually continue having sensations on their missing limbs as if they were still present. Signicant amount of such sensations are painful and referred as Phantom Limb Pain (PLP). Previous research has shown that providing the p ...

As technology improves, virtual reality interfaces based on body actions and expressions are becoming more and more important. In the domain of games, an evident application is the control of the hero by body actions. The robotics domain is another area where such an interface presents an attractive issue, especially in the tele-presence field. In this paper we discuss an action model along with a real-time recognition system and show how it may be used in virtual environments

We outline the creation of an Informed Environment, dedicated to urban life simulation. We propose methods and tools for creating and providing the information necessary for animating virtual humans in a city using an Informed Environment. The Informed Environment is based on a hierarchical decomposition of an urban scene into Environment Entities providing geometrical information as well as semantic notions, thus allowing a more realistic simulation of human behaviour. In this manner, virtual humans can in

In this paper we show how the mass properties of an articulated body, such as its center of mass and its moments of inertia, may be manipulated like any conventional end effector, with well-known iterative, numerical techniques. Within our interactive simulation testbed software, we illustrate this tool for the geometrical design of rigid bodies with prescribed mass properties, and for the manipulation of human figures in computer animation.

The perception of one's own body is subject to systematic distortions and can be influenced by exposure to visual stimuli showing distorted bodies. In Virtual Reality (VR), echoing such body judgment inaccuracies, avatars with strong appearance dissimilari ...

There are many possible ways of identifying the posture of a human character from a set of known positions. These methods differ in subtle but important ways. We propose an alternative method to the Jacobian based inverse kinematics, one which allows for simple calibration, allows for sensor slippage, and can take advantage of knowledge of the type of motion being performed. This approach gives real time conversion of magnetic sensor measurements into human anatomical rotations. Our converter is used in a w

Motion blending is widely accepted as a standard technique in computer animation, allowing the generation of new motions by interpolation and/or transition between motion capture sequences. To ensure smooth and seamless results, an important property has t ...

In this paper we propose the Middle-Axis-Rotation (MAR) parametrization of human limbs that addresses the ill-conditioned cases of analytical Inverse Kinematics (IK) algorithms. The MAR parametrization is singularity-free in the reach space of the human li ...

Rendering and animating in real-time a multitude of articulated characters presents a real challenge, and few hardware systems are up to the task. Up to now, little research has been conducted to tackle the issue of real-time rendering of numerous virtual humans. This paper presents a hardware-independent technique that improves the display rate of animated characters by acting on the sole geometric and rendering information. We first review the acceleration techniques traditionally in use in computer graph

Computer-based simulations of human hip joints generally include investigating contacts happening among soft or hard tissues during hip movement. In many cases, hip movement is approximated as rotation about an estimated hip center. In this paper, we inves ...

The relative location of human body parts often materializes the semantics of on-going actions, intentions and even emotions expressed, or performed, by a human being. However, traditional methods of performance animation fail to correctly and automaticall ...

In this paper, we present a new method for solving the Motion Retargeting Problem, by using an intermediate skeleton. This allows us to convert movements between hierarchically and geometrically different characters. An Inverse Kinematics engine is then used to enforce Cartesian constraints while staying as close as possible to the captured motion.

When placed inside an immersive virtual simulation, subjects will tend to experience the feeling of being 'really there' and to respond realistically to their environment, forgetting that it is not real. This behaviour is observed when subjects experience ...

Human reaching in a 3D environment is an interesting matter of research due to its application to workplace or vehicle-interior design. We introduce a 3D environment where a virtual human performs reaching tasks over 3D objects in the world. This environment also provides tools to generate and visualize reachable volumes. Reachable spaces are approximated using adjacent box-shaped voxels. We define several strategies in order to model different types of reaching, and we employ our system to construct and an

This paper aims to propose a novel approach to generate new generic human walking patterns using motion-captured data, leading to a real-time engine intended for virtual humans animation. The method applies the PCA (principal component analysis) technique on motion data acquired by an optical system to yield a reduced dimension space where not only interpolation, but also extrapolation are possible, controlled by quantitative speed parameter values. Moreover, with proper normalization and time warping metho

Real-time animation of virtual humans requires a dedicated architecture for the integration of different motion control techniques running into so-called actions. In this paper, we describe a software architecture called AGENTlib for the management of action combination. Considered actions exploit various techniques from keyframe sequence playback to inverse kinematics and motion capture. Two major requirements have to be enforced from the end user viewpoint: first, that multiple motion controllers can cont

The recognition of daily human activities is a decisive interface component for more intuitive virtual reality (VR) interactions. In this paper, we describe a hierarchical model of body actions based on fine-grained action primitives. The associated recognition algorithm allows on-the-fly identification of simultaneous actions. Measurements highlight robustness to participants' variability and high detection rates when using the full potential of the action model. An example illustrates an interaction with

We present a new method for solving the motion retargeting problem, by using an intermediate skeleton. This allows us to convert movements between hierarchically and geometrically different characters. An inverse kinematics engine is then used to enforce Cartesian constraints while staying as close as possible to the captured motion

Since their inception, interactive virtual environments have not been able to interpret users' gestures. Researchers have investigated a few tentative solutions, but most of them concern a specific set of body parts like hands, arms, or facial expressions. However, when placing a participant in a virtual world to interact with synthetic inhabitants, it would be more convenient and intuitive to use body-oriented actions. To achieve this, we developed a hierarchical model of human actions based on fine-graine

We propose an efficient kinematic position control for the center of mass of an articulated arm. The algorithm integrates the context of multiple joints reaching their limit value together with a singular configuration on the remaining joint space. We demonstrate the resulting fine control by interactively outlining the reachable area borders of the center of mass (in a 2D context for clarity). Moreover, the identification is also possible under any position or orientation constraint of an end effector. Thi

Ronan Boulic

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A two-arm coordination model for phantom limb pain rehabilitation

Body expression in virtual environments

An Informed Environment dedicated to the simulation of virtual humans in urban context

Kinematic control of the mass properties of redundant articulated bodies

An embodied body morphology task for investigating self-avatar proportions perception in Virtual Reality

A real time anatomical converter for human motion capture

On-line adapted transition between locomotion and jump

Singularity Free Parametrization of Human Limbs

Real-time display of virtual humans: levels of details and impostors

Sensitivity of hip tissues contact evaluation to the methods used for estimating the hip joint center of rotation

Egocentric Mapping of Body Surface Constraints

Using an Intermediate Skeleton and Inverse Kinematics for Motion Retargeting

Assessing the Impact of Mixed Reality Immersion on Presence and Embodiment

Bringing the human arm reachable space to a virtual environment for its analysis

PCA-based walking engine using motion capture data

Integration of motion control techniques for virtual human and avatar real-time animation

Live participant's action recognition for virtual reality interactions

Using an intermediate skeleton and inverse kinematics for motion retargeting

Interacting with virtual humans through body actions

Interactive identification of the center of mass reachable space for an articulated manipulator