Project : evasion
Section: Scientific Foundations
The synthesis of natural scenes has only been studied very recently compared to that of manufacturing environments, due to the difficulty in handling the high complexity of natural objects and phenomena. This complexity can express itself either in the number of elements (e.g. a prairie, hair), in the complexity of the shapes (e.g., many vegetable forms or animal organisms), of motions (e.g. a cloud of smoke, a stream), or of the local appearance of the objects (a lava flow).
To tackle this challenge:
we exploit the a priori knowledge from other sciences as much as possible, in addition to inputs from the real world such as images and videos.
we take a transversal approach with respect to the classical decomposition of Computer Graphics into Modelling, Rendering and Animation: we instead study the modelling, animation and visualisation of a phenomenon in a combined manner.
we reduce computation time by developing alternative representations to traditional geometric models and finite element simulations: hierarchies of simple coupled models instead of a single complex model; multi-resolution models and algorithms; adaptive levels of detail.
we take care to keep an intuitive user control.
we validate our results by comparing to images of the real phenomena, based on perceptual criteria.
Our research strategies are twofold:
Development of fundamental tools, i.e. of new models and algorithms satisfying the conditions above. Indeed, we believe that there are enough similarities between natural objects to factorise our efforts by the design of these generic tools. For instance, whatever their nature, natural objects are subject to physical laws that constrain their motion and deformation, and sometimes their shape (which results from the combined actions of growth and aging processes). This leads us to conduct research in adapted geometric representations, physically-based animation, collision detection, and phenomenological algorithms to simulate growth and aging phenomena. Secondly, the high number of details, sometimes similar at different resolutions, that can be found in natural objects leads us to the design of specific adaptive or multi-resolution models and algorithms. Lastly, being able to efficiently display very complex models and data-sets is required in most of our applications, which leads us to contribute to the visualisation domain.
Validation of these models by their application to specific natural scenes. We are currently covering scenes from the mineral kingdom (lava-flows, mud-flows, avalanches, streams, smoke, cloud) to the animal kingdom (animals in motion, parts of the human body, from internal organs dedicated to medical applications to skin, faces and hair needed for character animation), without forgetting vegetal scenes (complex vegetable shapes, specific material such as tree barks, animated prairies, meadows and forests).