Anatomically accurate modeling and rendering of the human eye

Recovering anatomical features of organic materials is a challenging issue. The human eye, as an important part of the non verbal communication, needs to be accurately modeled and rendered to increase the realism of virtual characters. The recent improvements of the graphics hardware offer the opportunity of rendering complex organic materials, following correct anatomical properties. We propose a novel method that allows to recover the iris structure and scattering features from a single eye photograph. In this aim, we developed a method to unrefract iris photographs. We model the iris using the Subsurface Texture Mapping representation which allows to describe the relieves of the human iris. Finally, we introduce a refraction function for accurate real-time rendering of the eye, accounting for the refraction of the light at the corneal interface

Radiance Caching for Efficient Global Illumination Computation

In this paper we present a ray tracing based method for accelerated global illumination computation in scenes with low-frequency glossy BRDFs. The method is based on sparse sampling, caching, and interpolating radiance on glossy surfaces. In particular we extend the irradiance caching scheme of \cite{ward88ray} to cache and interpolate directional incoming radiance instead of irradiance. The incoming radiance at a point is represented by a vector of coefficients with respect to a spherical or hemispherical basis. The surfaces suitable for interpolation are selected automatically according to the glossiness of their BRDF. We also propose a novel method for computing translational radiance gradient at a point

Profiling of G protein-coupled receptors in vagal afferents reveals novel gut-to-brain sensing mechanisms

Objectives: G protein-coupled receptors (GPCRs) act as transmembrane molecular sensors of neurotransmitters, hormones, nutrients, and metabolites. Because unmyelinated vagal afferents richly innervate the gastrointestinal mucosa, gut-derived molecules may directly modulate the activity of vagal afferents through GPCRs. However, the types of GPCRs expressed in vagal afferents are largely unknown. Here, we determined the expression profile of all GPCRs expressed in vagal afferents of the mouse, with a special emphasis on those innervating the gastrointestinal tract. Methods: Using a combination of high-throughput quantitative PCR, RNA sequencing, and in situ hybridization, we systematically quantified GPCRs expressed in vagal unmyelinated Nav1.8-expressing afferents. Results: GPCRs for gut hormones that were the most enriched in Nav1.8-expressing vagal unmyelinated afferents included NTSR1, NPY2R, CCK1R, and to a lesser extent, GLP1R, but not GHSR and GIPR. Interestingly, both GLP1R and NPY2R were coexpressed with CCK1R. In contrast, NTSR1 was coexpressed with GPR65, a marker preferentially enriched in intestinal mucosal afferents. Only few microbiome-derived metabolite sensors such as GPR35 and, to a lesser extent, GPR119 and CaSR were identified in the Nav1.8-expressing vagal afferents. GPCRs involved in lipid sensing and inflammation (e.g. CB1R, CYSLTR2, PTGER4), and neurotransmitters signaling (CHRM4, DRD2, CRHR2) were also highly enriched in Nav1.8-expressing neurons. Finally, we identified 21 orphan GPCRs with unknown functions in vagal afferents. Conclusion: Overall, this study provides a comprehensive description of GPCR-dependent sensing mechanisms in vagal afferents, including novel coexpression patterns, and conceivably coaction of key receptors for gut-derived molecules involved in gut-brain communication. Keywords: G protein-coupled receptors, Vagal afferent nerves, Gut-brain axis, Gut hormones, GLP1R, NTSR

Radiance caching and graphics hardware for real-time global illumination in dynamic scenes

Cette thèse apporte quatre contributions dans le domaine de la simulation d éclairage accélérée par cartes graphiques. (1) Nous proposons une base de fonctions pour la représentation précise et compacte de fonctions basse fréquence définies sur l'hémisphère : les harmoniques hémisphériques. Cette base est appliquée dans l algorithme de cache de luminance. (2) Nous introduisons une reformulation des algorithmes de cache d'éclairement et de luminance, permettant une implémentation simple et efficace sur carte graphique. (3) Nous étendons la méthode d interpolation de l algorithme de cache d éclairement au domaine temporel. Notre implémentation sur cartes graphiques permet de réduire significativement les temps de calcul et d augmenter la qualité de rendu dans des scènes dynamiques. (4) Nous proposons une technique précise d estimation de densité pour l algorithme de rendu par cartes de photons sans regroupement final.RENNES1-BU Sciences Philo (352382102) / SudocRENNES-INRIA Rennes Irisa (352382340) / SudocSudocFranceF

(Ir)Radiance Caching

• A reformulation for hardware implementatio

Improved Radiance Gradient Computation

We describe a new and accurate algorithm for computing translational gradients of incoming radiance in the context of a ray tracing-based global illumination solution. The gradient characterizes how the incoming directional radiance function changes with displacement on a surface. We use the gradient for a smoother radiance interpolation over glossy surfaces in the framework of the radiance caching algorithm. The proposed algorithm generalizes the irradiance gradient computation by [Ward and Heckbert 1992] to allow its use for non-diffuse, glossy, surfaces. Compared to previous method for radiance gradient computation, the new algorithm yields better gradient estimates in the presence of significant occlusion changes in the sampled environment, allowing a smoother indirect illumination interpolation. Copyright © 2005 by the Association for Computing Machinery, Inc

Photon driven irradiance cache

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GPU-Based Volume Rendering for Medical Imagery

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Temporal Radiance Caching

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