Expressive rendering



There is no reason to restrict the use of computers to the simulation of physically accurate lighting. Indeed it has been recognized in recent years that computer processing opens fascinating new avenues for rendering images that convey particular views, emphasis, or style. These approaches are often referred to as "non-photorealistic rendering", although we prefer the term "expressive rendering" to this negative definition.

A part of computer graphics can be viewed as a visual communication tool. Such a point of view implies several goals that we target with expressive rendering. In particular the user of an expressive rendering tool should be able to produce the images that corresponds to his own goals.

This involves, in particular, significant work on the notion of relevance, which is necessarily application-dependent. The relevance should guide the level of abstraction of the rendered scene to let the user emphasize the most important elements of the input 3d scene. It can also be defined from a levels-of-detail point of view: not only can we adapt the geometry to decrease the computation time, but we can also adapt the rendering style to meet the user's goals.

Another research direction for expressive rendering concerns rendering styles: in many cases it should be possible to define the constitutive elements of styles, allowing the application of a given rendering style to different scenes, or in the long term the capture of style elements from collections of images.

Finally, since the application of expressive rendering techniques generally amounts to a visual simplification, or abstraction, of the scene, particular care must be taken to make the resulting images consistent over time, for interactive or animated imagery. This leads to various projects targeting the temporal coherence of animated scenes.

Research projects

Abstraction, level of details

Abstraction is one of the main issues of expressive rendering. Indeed we think that the impact of an image in terms of message transmission is related to a carefull abstraction of each part of the image, depending on the targeted goal.

ARTIS is working on several project in this research field:

User oriented algorithms

We think that the user (artist, architect, technical designer, ...) must be able to control the rendering. It means that we have to find a compromise between automation and what could be done by hand. Our idea is to try to give as much parameters as possible to the user or to let him describe what he wants by giving examples.

ARTIS is working on several project in this research field:

Temporal coherence

As soon as we want to animate a 3D scene rendered with primitives that are not a pixel (lines, strokes, dots, ...), we have to deal with temporal coherence.

ARTIS is working on several project in this research field:

Collaborations and applications

One of our targeted field is archaelogy.
The ARC INRIA project ARCHEOS has been a first attempt to work with archaelogists and several publications have been made during this 2 years collaboration :
A Physically-Based Particle Model of Emergent Crowd Behaviors  
Laure Heigeas, Annie Luciani, Joëlle Thollot, Nicolas Castagné - Graphicon - 2003
Dynamic Canvas for Immersive Non-Photorealistic Walkthroughs  
Matthieu Cunzi, Joëlle Thollot, Sylvain Paris, Gilles Debunne, Jean-Dominique Gascuel, Frédo Durand - Graphics Interface - june 2003
Virtual immersion in the ancient Greek city of Argos  
Isabelle Ratinaud, Joëlle Thollot - International Congress of Classical Archaeology - 2003

The ARC INRIA MIRO continues the collaboration with archaeologists adressing the problem of producing legible renderings.


François Sillion
Joëlle Thollot
Cyril Soler
Matthew Kaplan
Pascal Barla
David Vanderhaeghe
Hedlena Bezerra