François Faure
Postdoc researcher in computer animation Technische Universität Wien, Karlsplatz 13, Wien, Austria francois@cg.tuwien.ac.at http://www.cg.tuwien.ac.at/~francois/Public/Work/index.html tel: (+431) 588 01 18 686 fax: (+431) 588 01 18 698 
My curriculum vitae includes a list of publications.
My research focuses on tradingoff efficiently accuracy for speed in physicallybased computer animation. This implies using fast equation solution algorithms along with robust integration schemes allowing the use of long time steps. Here are some recent results. The following animations have been recorded in realtime using screen capture on a standard SGI O2 workstation R5000 180 MHz.
video (2Mo) 
video (900 ko)  video (830 ko) 
Related work:
Computing the dynamics of an articulated structure requires solving a linear equation system, which requires a lot of computation time. I developped a new approach allowing the user to tradeoff accuracy for computation time. Acyclic structures are handled in linear time using wellknown methods. The closed loop constraints are iteratively solved using a conjugate gradient algorithm, allowing the user to tune the accuracy or the computation time. This work is currently submitted for publication.
video (quicktime.gz, 935ko) 
Related work:
Contact force computation is a difficult problem since it involves inequalities such as repulsion or friction coefficient. My approach is to iteratively refine a global solution. At each step, assumptions are made about the behavior of each contact (sticking, sliding or vanishing), which allow to obtain a regular equation system. The solution of the equation system provide values which must be compatible with the assumptions (no attractive force, etc.). New assumptions are made in case of inconsistency. The algorithm converges toward a correct solution. This approach allows tradingoff accuracy for computation time.




Related work:
I am the informal coordinator of the PAVRML project on collaborative and distributed animation, which involves several research institutes of the European PAVR project. The PAVRML project consists in gathering over the internet different applications of computer animation. An interface is used to communicate between several applications which would be incompatible otherwise, while a server manges the consistency of a distributed world.
Related work:
Articulated structures can be applied to the tracking of user body in virtual environments. Occlusion can thus be generated using the zbuffer, improving realism. More detail on this work can be found there.
Related work:
In this work, we analyzed human gaits. Starting from biomedical data, we applied inverse dynamics to compute the corresponding forces and torques. The difficulty is to handle discontinuities (the contact between the foot and the ground is not permanent) and friction forces. The following animation shows a gait reconstructed from incomplete data.
video (quicktime.gz, 57ko) 
Related work:
Most of my previous work on animation is gathered in Tabule, the simulator I designed during my PhD. I also worked on imagebased modeling using a photometric approach.
The purpose is, by using CCD camera images, to automatically create objects models which could be used for image synthesis. The models must include both the geometry and the reflectance of the surfaces. For example, a surface can be modeled using three images under different known lighting conditions:
This is the reconstructed surface, seen from another point of view.
Related work:
Institute of Computer Graphics / Visualization and Animation Group / Staff