Représentations d'arbres réalistes et efficaces pour la synthèse d'images de paysages. (Efficient Rendering of Realistic Trees Representations for Computer Graphics)
نویسنده
چکیده
This PhD thesis is dedicated to the representation of trees for high quality or real timelandscapes rendering. Techniques of tree modeling give good results in terms of diversity of species andshapes. However, the multitude of polygons of their geometrical representations generates a high computingcost and important problems of aliasing at rendering. Mesh simplification in order to build levels of details isnot adapted to trees since it alters global illumination and opacity, because of the discontinuous repartition ofthe leaves. With the idea of representing groups of primitives (leaves or branches) using packets combininggeometric and photometric appearance, we have introduced two new representations.The first, intended to high quality rendering, is based on the analytic computation of the global illu-mination model of a geometric branch of needles. By using the knowledge of the geometric distributionof needles, we computed analytically a hierarchy of three shaders able to represent effect of lower levels,without sampling and with self-shadowing and visibility. The analytic aspect of these shaders allows in thesame time the acceleration of computing time and good image quality, particularly with little aliasing.The second, intended to real time rendering, is based on hierarchical sets of images corresponding to thesampling of view and light directions, which we render using billboards by interpoling images. We associatea precomputed visibility structure, based on visibility cubes maps, for self-shadowing and shadows. Ourimplementation allows the interactive rendering of a forest of 1000 trees with shading, self-shadowing,shadowing and the capability of moving light position interactively.
منابع مشابه
Modélisation et rendu d'images réalistes de paysages naturels. (Modeling and Rendering of natural landscapes realistic images)
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau...
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