Direction des Relations Internationales (DRI)

INRIA Programme  "Associate Teams "
(Renwal Form)

I. DEFINITION

ASSOCIATE TEAM

 		   RTR2A
selection
 2004     extended to a new partner in 2008     
Renewal
2009


INRIA project: SIAMES/BUNRAKU
 Foreign partners
Unité de recherche INRIA : Rennes
Thème INRIA : Cognitive
  University of Central Florida, University of Utah, US
 
 
French Coordinator
Foreign Coordinator 2
 Foreign Coordinator 2         
Last Name, First Name
  Kadi Bouatouch
   Sumant Pattanaik
 Charles Hansen
Title  Professor   Associate Professor
 Professor
Institution
(précisez le département et/ou le laboratoire)		  INRIA Rennes, Université de Rennes 1
 Computer Graphics Lab. University of Central Florida,
 School of Computer Science 		School of Computing,
Adress
  Campus de Beaulieu, 35042 Rennes Cedex
  School of Computer Sciences, University of Central Florida
Orlando, Florida, 32816-2362, USA

 School of Computing, University of UTAH
50 S. Central Campus Drive, RM 3190 MEB
Salt Lake City, Utah 84112
URL  www.irisa.fr/siames/Kadi.Bouatouch  http://www.cs.ucf.edu/~sumant/ http://www.cs.utah.edu/~hansen/
Tel  02 99 84 72 58
  +1 407 823 2638
 +1 801 581 3154
Fax  02 99 84 71 71
  +1 407 823 5419
 +1 801 581 5843
E-mail  kadi@irisa.fr  sumant@cs.ucf.edu hansen@cs.utah.edu



Brief description of the proposal 

 Rendu et Illumination Globale en Temps Réel------- Rendering and  Global illumination in Real-Time

Description (about 10 lignes) :
The targetted objective is real time rendering and real-time golbal illumination computation for static and dynamic scenes. The first objective is real-time high fidelity rendering of dynamic scenes. Rendering complex scenes using a classical graphics pipeline (Z-buffering, Phong's shading model, multitexturing, etc.) can be efficiently performed with commodity graphics cards. However, real-time rendering of scenes, for which global illumination is computed, still is a challenge for many researchers. Indeed, global illumination followed by a rendering step (that we call high fidelity rendering) is a demanding process in terms of computing and memory resources. The approch proposed in this collaboration has to intensively exploit the performances of the new graphics cards to meet the real-time constraint. The second objective is  to extend our global illumination algorithms to volumetric data such as medical images and other semi-transparent objects.  Light transport in such objects must account for:  multiple scattering, attenuation effects, etc. Computing and rendering these effects amounts to solve the radiative transfer equation which is very time consuming. Realistic and fast approximations are needed.

Detailed Presentation of the Associate Team

 

1. Scientific Objectives of the proposal 

Our objective is real-time high fidelity rendering of dynamic scenes. Rendering complex scenes using a classical graphics pipeline (Z-buffering, Phong's shading model, multitexturing, etc.) can be efficiently performed with commodity graphics cards. However, real-time rendering of scenes, for which global illumination is computed, still is a challenge for many researchers. Indeed, global illumination followed by a rendering step (that we call high fidelity rendering) is a demanding process in terms of computing and memory resources.

Computing global illumination amounts to solve the rendering equation which is an integral equation. Unfortunately, this equation does not have an analytic solution in general. Consequently, Monte Carlo integration is the method of choice for solving it. However, Monte Carlo integration requires the computation of many samples, which makes it demanding in terms of computation time. Our objective is to propose an algorithm which allows for interactive hgih fidelity rendering and global illumination.

Our approach makes use of ray tracing, Monte Carlo integration and caching. It aims at extending the ``irradiance caching'' algorithm (Greg Ward 1994). Note that this algorithm is based on the observation that the diffuse component of radiance, reflected on a diffuse surface and due to indirect illumination, changes very slowly on this surface. This allows to sparsely sample and to cache the incoming radiances at these samples, then to reuse the cached samples to estimate the incoming radiance at nearby points. This method is computationally efficient since the sampling is sparse. However it is limited to diffuse indirect lighting computation.Our work consists in extending the irradiance caching approach to indirect glossy global illumination. Our algorithm relies on ``radiance caching''. It is based on the caching of directional incoming radiances. We have first designed a new set of basis functions defined on the hemisphere to represent directional incoming radiance and BRDFs (Gautron et al. 2004). This representation, along with a new gradient-based interpolation method (Krivanek et al. 2004), are the bases of our radiance caching-based algorithm. We are also experimenting with spherical wavelets to represent BRDFs and incoming radiances. Our radiance caching algorithm will intensively exploit the power of programmable GPUs (Gautron et al. 2005), to make global illumination more interactive. .*

We sincerely think that there is a long way to go to be capable of performing global illumination computation in a moderate time for complex scenes (such as natural scenes). We think new methods are needed to address the problem of complexity in terms of geometry, photometry and illumination effects.  Is the kind of method we already proposed is valid for realistic 3D movies and for high quality video games in case of highly complex scenes? Our objective is to take up this challenge.
We would like to extend our global illumination algorithms to volumetric data such as medical images and other semi-transparent objects.  Light transport in such objects must account for:  multiple scattering, attenuation effects, etc. Computing and rendering these effects amounts to solve the radiative transfer equation which is very time consuming. Realistic and fast approximations are needed. The Utah group has a long experience in this field of research. This group has, for example, proposed a new volumetric lighting model which is fast and efficient. Another skill of this group, that could be beneficial for us, is parallel algorithms for graphics and scientific visualisation. We are interested in the new PARALLEL PROGRAMMING language named CUDA.

2. Presentation of the partners 

Kadi Bouatouch  is an electronics and automatic systems engineer (ENSEM 1974). He was awarded a PhD in 1977 and a higher doctorate on computer science in the field of computer graphics in 1989. His is working on global illumination, lighting simulation for complex environments, GPU based rendering and computer vision..  He is currently Professor at the university of Rennes 1 (France) and researcher at INRIA Bretagne Atlantique.  He is member of the INRIA research group Bunraku.


Sumant Pattanaik is an associate professor of Computer Science in the School of Electrical Engineering and Computer Science at University of Central Florida , Orlando. Previously, he was a Research Associate at the Cornell Program of Computer Graphics, Cornell University (1995-2001), a Post-Doctoral Associate at the SIAMES group of  IRISA/INRIA, Rennes, France (1993-1995), and a Senior Staff Scientist at the Graphics Department of NCST, Bombay (1985-1995). He received my PhD from the Department of Computer Science and Information Science of BITS, Pilani  in November 1993. His area of interest includes Computer Graphics, Virtual Reality and Visualization. His current research is in the area of Realtime Realistic Image Synthesis.
His is the head of the computer graphics group of  UCF.

Charles Hansen is professor at the school of computing of the university of Utah. His areas of interest are:  Large Scale Scientific Visualization, Rendering Techniques and Computer Graphics, Parallel Algorithms, Distributed Computation, 3D Shape representation, Computer Vision.  He is member of the graphics group of this school.

Sumant Pattanaik spent two years in our group betwenn 1993 and 1995 as a postdoc. When he joined UCF in 2001 as an associate professor, we decided to collaborate and exchange students. He welcomed two of my PhD students in 2003 and invited me as a vising professor in 2004.  Then we applied for the programme of Associate Team.
Regarding Chuck Hansen, I have kown him  for many years. While attending the same conference, we decided to collaborate to exchange our skills in global illumination, volume rendering and parallel computing. I invited him for two months in 2007 as a visiting professor. This was an opportunity to include him in the associate team in 2008., which has been accepted by INRIA.

3. Impact 

Sumant Pattanaik and Kadi Bouatouch have a long experience in computer graphics, especially in rendering, global illumination and visual perception. The associate team has made possible a fruitful collaboration in terms of publications, see publi1 and publi2. The corresponding groups have similar objectives: real-time rendering and global illumination.

Chuck Hansen has a long experience in computer graphics, visualization and parallelism for graphics. The bunraku and UCF groups will benefit from his skills through this collaboration . The Bunraku and UCF teams would  acquire a skill in volume visualization and parallelism while the Utah team will benefit from our experience in rendering and global illumination.

4. Miscellaneous : 

II. OUTCOME of 2008 and Balance Sheet

This was the first year of the extended associate team. Indeed,  the university of UTAH has joined us for a new adenture.

Scientific Report for 2008

In 2008 we have still addressed the following topics : (1) real-time rendering of complex nature scenes with dynamic lighting and shadow casting, (2) Real-time rendering of globally illuminated volume data.

       Publications in 2008 

           PhD and Master supervision

       Kévin Boulanger, supervised by  Sumant Pattanaik and Kadi Bouatouch,  has defended his thesis in Orlando on the 10th of July 2008.
       Guillaume François will defend his PhD thesis on the 17th of October 2008. Guillaume's Master  has been jointy supervised  by Sumant and Kadi Bouatouch.

        Previous programme 2007-2008

        See Formulaire08 


III. EXPECTATIONS 2009

Work Plan

The objective for 2009 is the following:

           We sincerely think that there is a long way to go to be capable of performing global illumination computation in a moderate time for complex scenes containing different types of material (BRDF, BTF, BSSRDF, textures, etc.). We think new methods are needed to address the problem of complexity in terms of geometry, photometry and illumination effects.  Some  methods have been already proposed  but only for scenes of moderate complexity and moderate lighting effects.  We need to go further by handling at once glossyness, transluscent objects,  scattering, etc. This work will be done in collaboration with UCF.           We would like to continue our work on adapting our global illumination algorithms to the computation of multiple scattering within  volumetric data such as medical images and other semi-transparent objects.  Light transport in such objects must account for:  multiple scattering, attenuation effects, etc. Computing and rendering these effects amounts to solve the radiative transfer equation which is very time consuming. Based on our experience in global illumination,  our approach will provide a real-time approximation of  multiple scattering within volumetric objects to improve realism and make the rendered images more appealing and precisely interpreted by doctors. This work will be done in collaboration with the university of Utah.

 

Exchange Programme with projected budget 

1. Exchanges

Professor Charles Hansen will spend two weeks in Rennes in 2009. I will visit Utah for one week.
These visits will allow us to:
I will send one of my PhD students (Jonathan Brouillat) to Utah. He will spend one month.
I will welcome two PhD students: one from Utah (Mathias Schott, two months, from June 2009 to july 2009)  and and one from UCF (Juraj Obert, four months, from February 2009 to May 2009). I have already welcomed and worked with Mathias Schott in 2008 about rendering and mutliple scattering of volume data in real-time. We will continue this work in 2009.
I will start working with Juraj Obert about a new caching algorithm for global illumination computation.  

 1. ESTIMATION OF THE EXPENSES ENTAILED BY THE  MISSIONS INRIA TOWARD THE PARTNERS 
Number of people
Estimated cost
Chercheurs confirmés  1  2200 €
Post-doctorants
    
Doctorants  1  2000 €

Stagiaires

   
Autre (précisez) :
    
   Total
  3  4200 €

 

 2. ESTIMATION OF THE EXPENSES ENTAILED BY THE  INVITATIONS OF THE PARTNERS
Number of people
Estimated cost
Chercheurs confirmés  1  2200 €
Post-doctorants
    
Doctorants  2  8000 €

Stagiaires

   
Autre (précisez) :
    
   Total
  5  10200 €

2. Co-funding (external funding)

The first partner (UCF) has already financed Kevin Boulanger's PhD as well as his Master for more than two years (from february 2005 to august 2005 as a Master student, from september 2005 to august 2007  as a PhD student). Then, from september 2007 to september 2008 Kevin Boulanger got a grant from INRIA Rennes Bretagne Atlantique.
The amounts corresponding to these fundings are detailed in  Formulaire08
It is true that the university of Utah  did not propose a funding  for now but  Charles Hansen is looking for a possible funding for this year.
Charles Hansen will visit us in November 2008 for a couple of days  (to participate in the defense committee of my PhD student, Guillaume François) .
This opportunity will allow us to find out some possible funding from Utah.
I have some contracts managed by the university of Rennes 1. I am responsible for these contracts. I porpose to use 6400 €  for our associate team.


EXPECTED EXTERNAL FUNDING
Institution
Amount
 University of Central Florida, USA
 Not this year
 University of Utah  Not this year
University of Rennes 1  (university contracts managed by  Kadi Bouatouch)  6400 €
   
   
Total
 6400 €

3. Budget request

Comments
Amount
A. Global cost of the proposal  (total tables 1 and 2 : invitations, missions, ...)  14400 €
B. Co-funding used  (Other fundings than "Associate Team Equipe")  6400 €
Requested funding for the "Associate Team" (A.-B.) (maximum 10 K€)
 8000 €

 

 

© INRIA - mise à jour le 15/08/2008