Path tracing multivue adaptatif

International audienceRendering photo-realistic image sequences using path tracing and Monte Carlo integration often requires sampling a large number of paths to get converged results. In the context of rendering multiple views or animated sequences, such sampling can be highly redundant. Several methods have been developed to share sampled paths between spatially or temporarily similar views. However, such sharing is challenging since it can lead to bias in the final images. Our contribution is a Monte Carlo sampling technique which generates paths, taking into account several cameras. First, we sample the scene from all the cameras to generate hit points. Then, an importance sampling technique generates bouncing directions which are shared by a subset of cameras. This set of hit points and bouncing directions is then used within a regular path tracing solution. For animated scenes, paths remain valid for a fixed time only, but sharing can still occur between cameras as long as their exposure time intervals overlap. We show that our technique generates less noise than regular path tracing and does not introduce noticeable bias.Le rendu de séquences d'images photoréalistes en lancer de rayons nécessite souvent l'échantillonnage d'un grand nombre de chemins pour obtenir des résultats convergés. Dans le contexte du rendu multi-vue ou de séquences animées, cet échantillonnage peut être redondant. Plusieurs méthodes ont été développées pour réutiliser des chemins échantillonnés entre des vues proches spatialement ou temporellement. Cependant, un telle réutilisation est complexe car elle peut mener à du biais dans les images. Notre contribution est une technique d'échantillonnage qui génère des chemins en prenant en compte plusieurs caméras. Tout d'abord, nous échantillonnons la scène depuis toutes les caméras pour générer des points visibles. Ensuite, nous générons des directions par importance qui sont partagées par un sous-ensemble de caméras. Cet ensemble de points et de directions est ensuite utilisé dans une solution de lancer de rayons classique. Pour les scènes animées, les chemins ne sont réutilisables qu'à temps fixe, mais un partage peut toujours avoir lieu entre les caméras si leurs intervalles d'exposition se recouvrent. Notre technique génère moins de bruit que le path tracing classique à temps de calcul équivalent et n’introduit pas de biais perceptible

Interactive Curvature Tensor Visualization on Digital Surfaces

International audienceInteractive visualization is a very convenient tool to explore complex scientific data or to try different parameter settings for a given processing algorithm. In this article, we present a tool to efficiently analyze the curvature tensor on the boundary of potentially large and dynamic digital objects (mean and Gaussian curvatures, principal curvatures , principal directions and normal vector field). More precisely, we combine a fully parallel pipeline on GPU to extract an adaptive triangu-lated isosurface of the digital object, with a curvature tensor estimation at each surface point based on integral invariants. Integral invariants being parametrized by a given ball radius, our proposal allows to explore interactively different radii and thus select the appropriate scale at which the computation is performed and visualized

Linear Efficient Antialiased Displacement and Reflectance Mapping

International audienceWe present Linear Efficient Antialiased Displacement and Reflectance (LEADR) mapping, a reflectance filtering technique for displacement mapped surfaces. Similarly to LEAN mapping, it employs two mipmapped texture maps, which store the first two moments of the displacement gradients. During rendering, the projection of this data over a pixel is used to compute a noncentered anisotropic Beckmann distribution using only simple, linear filtering operations. The distribution is then injected in a new, physically based, rough surface microfacet BRDF model, that includes masking and shadowing effects for both diffuse and specular reflection under directional, point, and environment lighting. Furthermore, our method is compatible with animation and deformation, making it extremely general and flexible. Combined with an adaptive meshing scheme, LEADR mapping provides the very first seamless and hardware-accelerated multi-resolution representation for surfaces. In order to demonstrate its effectiveness, we render highly detailed production models in real time on a commodity GPU, with quality matching supersampled ground-truth images

Towards perceptual control of physically based spectral rendering

International audiencenot availabl

Géométrie pour l'informatique graphique

National audiencenon disponibl

Towards perceptual control of physically based spectral rendering

International audiencenot availabl

Etudes sur le lancer de rayons spectral

GRENOBLE-MI2S (384212302) / SudocST ETIENNE-BU Sciences (422182103) / SudocSudocFranceF

Pipeline graphique

National audiencenon disponibl

Pipeline graphique

National audiencenon disponibl

Élimination des parties cachées

National audiencenon disponibl