RE@CT - Immersive Production and Delivery of Interactive 3D Content

International audienceThis paper describes the aims and concepts of the FP7 RE@CT project. Building upon the latest advances in 3D capture and free-viewpoint video RE@CT aims to revolutionise the production of realistic characters and significantly reduce costs by developing an automated process to extract and represent animated characters from actor performance capture in a multiple camera studio. The key innovation is the development of methods for analysis and representation of 3D video to allow reuse for real-time interactive animation. This will enable efficient authoring of interactive characters with video quality appearance and motion

Camera cooperation for achieving visual attention

In this report we address the problem of establishing a computational model for visual attention using cooperation between two cameras. More specifically we wish to maintain a visual event within the field of view of a rotating and zooming camera through the understanding and modelling of the geometric and kinematic coupling between a static camera and an active camera. The static camera has a wide field of view thus allowing panoramic surveillance at low resolution. High-resolution details may be captured by a second camera, provided that it looks in the right direction. We derive an algebraic formulation for the coupling between the two cameras and we specify the practical conditions yielding a unique solution. We describe a method for separating a foreground event (such as a moving object) from its background while the camera rotates. A set of outdoor experiments shows the two-camera system in operation

Human Motion Tracking with a Kinematic Parameterization of Extremal Contours

This report addresses the problem of human motion tracking from image sequences. The human body is described by an articulated mechanical chain and human body-parts are described by volumetric primitives with curved surfaces. An extremal contour appears in an image whenever a curved surface turns smoothly away from the viewer. We describe a method that relies on a kinematic parameterization of such extremal contours. The apparent motion of these contours in the image plane is a function of both the rigid motion of the surface and the relative position and orientation of the viewer with respect to the curved surface. First, we describe a parameterization of an extremal-contour point, and its associated image velocity, as a function of the motion parameters of the kinematic chain associated with the human body. Second, we introduce the zero-reference kinematic model and we show how it may be used for human-motion modelling. Third, we show how the chamfer-distance may be used to measure the discrepancy between predicted extremal contours and observed image contours; Moreover we show how the chamfer distance can be used as a differentiable multi-valued function and how the tracker based on this distance can be cast in an optimization framework. Fourth, we describe a practical human-body tracker that may use an arbitrary number of cameras. One great methodological and practical advantage of our method is that it relies neither on model-to-image, nor on image-to-image point matches. In practice we model people with 5 kinematic chains, 19 volumetric primitives, and 54 degrees of freedom; We observe silhouettes in images gathered with several synchronized and calibrated cameras. The tracker has been successfully applied to several complex motions gathered at 30 frames/second.Dans ce rapport de recherche, nous nous intéressons au problème du suivi du mouvement humain à l'aide de plusieurs caméras. Le modèle que nous utilisons pour effectuer le suivi est décrit par une chaîne articulée ainsi que par des primitives solides. Les surfaces de ces primitives se projettent dans les images sous la forme de deux types de contours : les contours de discontinuité, qui apparaissent à l'intersection entre deux surfaces, et les contours extrémaux qui apparaissent lorsque la surface est tangente au rayon de vue. Dans ce rapport, nous décrivons une méthode de capture du mouvement basé sur l'observation des contours extrémaux. Pour cela, nous introduisons une paramétrisation explicite des contours extrémaux, applicable aux surfaces développables. Cette paramétrisation nous permet de relier le mouvement apparent des contours aux mouvements articulaires et aux positions et orientations des caméras. Dans un premier temps, nous explicitons la paramétrisation des contours extrémaux et donnons leur vitesse apparente dans les images en fonction des paramètres de la chaîne cinématique auquel la primitive est attachée. Dans un deuxième temps, nous introduisons la modélisation en référence zéro de la chaîne cinématique. Nous montrons comment intégrer cette modélisation dans celle de la chaîne cinématique humaine. Dans un troisième temps, nous montrons comment utiliser la distance de chanfrein pour déterminer l'erreur entre les contours extraits de l'image et les contours extrémaux du modèle. De plus, nous montrons que cette distance peut être différentiable et donc que nous pouvons aborder le problème du suivi de mouvement comme un simple problème de minimisation non-linéaire. Un avantage majeur tant du point de vue méthodologique que du point de vue pratique est que l'algorithme n'utilise ni de correspondances modèle à image, ni de correspondances image à image. En pratique, nous modélisons le corps humain avec 5 chaînes cinématiques, 19 cônes tronqués à base elliptique et 54 degrés de liberté. Nous observons les silhouettes et le contours dans les images acquises avec des caméras synchronisées et calibrées. L'algorithme de suivi a pu être testé avec succès sur des mouvements complexes

Annual sulfur cycle in a warm monomictic lake with sub-millimolar sulfate concentrations.

We studied the annual variability of the concentration and isotopic composition of main sulfur species and sulfide oxidation intermediates in the water column of monomictic fresh-water Lake Kinneret. Sulfate concentrations in the lake are <1 mM and similar to concentrations that are proposed to have existed in the Paleoproterozoic ocean. The main goal of this research was to explore biogeochemical constrains of sulfur cycling in the modern low-sulfate fresh-water lake and to identify which processes may be responsible for the isotopic composition of sulfur species in the Precambrian sedimentary rocks. RESULTS: At the deepest point of the lake, the sulfate inventory decreases by more than 20% between March and December due to microbial sulfate reduction leading to the buildup of hydrogen sulfide. During the initial stages of stratification, sulfur isotope fractionation between sulfate and hydrogen sulfide is low (11.6 ‰) and sulfur oxyanions (e.g. thiosulfate and sulfite) are the main products of the incomplete oxidation of hydrogen sulfide. During the stratification and at the beginning of the lake mixing (July-December), the inventory of hydrogen sulfide as well as of sulfide oxidation intermediates in the water column increases and is accompanied by an increase in sulfur isotope fractionation to 30 ± 4 ‰ in October. During the period of erosion of the chemocline, zero-valent sulfur prevails over sulfur oxyanions. In the terminal period of the mixing of the water column (January), the concentration of hydrogen sulfide decreases, the inventory of sulfide oxidation intermediates increases, and sulfur isotope fractionation decreases to 20 ± 2 ‰. CONCLUSIONS: Sulfide oxidation intermediates are present in the water column of Lake Kinneret at all stages of stratification with significant increase during the mixing of the water column. Hydrogen sulfide inventory in the water column increases from March to December, and sharply decreases during the lake mixis in January. Sulfur isotope fractionation between sulfate and hydrogen sulfide as well as concentrations of sulfide oxidation intermediates can be explained either by microbial sulfate reduction alone or by microbial sulfate reduction combined with microbial disproportionation of sulfide oxidation intermediates. Our study of sulfur cycle in Lake Kinneret may be useful for understanding the range of biogeochemical processes in low sulfate oceans over Earth history

Impact of Aeolian Dry Deposition of Reactive Iron Minerals on Sulfur Cycling in Sediments of the Gulf of Aqaba

The Gulf of Aqaba is an oligotrophic marine system with oxygen-rich water column and organic carbon-poor sediments (≤0.6% at sites that are not influenced by anthropogenic impact). Aeolian dust deposition from the Arabian, Sinai, and Sahara Deserts is an important source of sediment, especially at the deep-water sites of the Gulf, which are less affected by sediment transport from the Arava Desert during seasonal flash floods. Microbial sulfate reduction in sediments is inferred from the presence of pyrite (although at relatively low concentrations), the presence of sulfide oxidation intermediates, and by the sulfur isotopic composition of sulfate and solid-phase sulfides. Saharan dust is characterized by high amounts of iron minerals such as hematite and goethite. We demonstrated, that the resulting high sedimentary content of reactive iron(III) (hydr)oxides, originating from this aeolian dry deposition of desert dust, leads to fast re-oxidation of hydrogen sulfide produced during microbial sulfate reduction and limits preservation of reduced sulfur in the form of pyrite. We conclude that at these sites the sedimentary sulfur cycle may be defined as cryptic

RE@CT - Immersive Production and Delivery of Interactive 3D Content

International audienceThis paper describes the aims and concepts of the FP7 RE@CT project. Building upon the latest advances in 3D capture and free-viewpoint video RE@CT aims to revolutionise the production of realistic characters and significantly reduce costs by developing an automated process to extract and represent animated characters from actor performance capture in a multiple camera studio. The key innovation is the development of methods for analysis and representation of 3D video to allow reuse for real-time interactive animation. This will enable efficient authoring of interactive characters with video quality appearance and motion

The refinement of the haemagglutinin membrane glycoprotein of influenza virus

The crystal structure of the haemagglutinin glycoprotein, a trimer from the membrane of influenza virus, has been refined at 3.0 Å resolution to an R factor of 20.4%. The first 23 cycles were carried out on coordinates of an averaged monomer determined from a non-crystallographically threefold-symmetry-averaged electron density map. The contribution of structure factors to the least-squares equations were determined from non-crystallographically averaged gradient difference and curvature Fourier maps. The refinement was restrained using the Hendrickson & Konnert algorithm. These initial cycles were followed by 25 cycles of refinement with trigonometric evaluation of the derivatives on the complete trimer (208 422 daltons) on a Cray 1/S. Forty-eight water molecules and portions of five N-linked oligosaccharides were identified

The protective role of sphingosine-1-phosphate against the action of the vascular disrupting agent combretastatin A-4 3-O-phosphate

Solid tumours vary in sensitivity to the vascular disrupting agent combretastatin A-4 3-O-phosphate (CA4P), but underlying factors are poorly understood. The signaling sphingolipid, sphingosine-1-phosphate (S1P), promotes vascular barrier integrity by promoting assembly of VE-cadherin/β-catenin complexes. We tested the hypothesis that tumour pre-treatment with S1P would render tumours less susceptible to CA4P. S1P (1μM) pretreatment attenuated an increase in endothelial cell (HUVEC) monolayer permeability induced by 10μM CA4P. Intravenously administered S1P (8mg/kg/hr for 20 minutes then 2mg/kg/hr for 40 minutes), reduced CA4Pinduced (30mg/kg) blood fow shut-down in fbrosarcoma tumours in SCID mice (n≥7 per group), as measured by tumour retention of an intravenously administered fuorescent lectin. A trend towards in vivo protection was also found using laser Doppler fowmetry. Immunohistochemical staining of tumours ex vivo revealed disrupted patterns of VE-cadherin in vasculature of mice treated with CA4P, which were decreased by pretreatment with S1P. S1P treatment also stabilized N-cadherin junctions between endothelial cells and smooth muscle cells in culture, and stabilized tubulin flaments in HUVEC monolayers. We conclude that the rapid shutdown of tumour microvasculature by CA4P is due in part to disruption of adherens junctions and that S1P has a protective effect on both adherens junctions and the endothelial cell cytoskeleton

Influenza hemagglutinin stem-fragment immunogen elicits broadly neutralizing antibodies and confers heterologous protection

Influenza hemagglutinin (HA) is the primary target of the humoral response during infection/vaccination. Current influenza vaccines typically fail to elicit/boost broadly neutralizing antibodies (bnAbs), thereby limiting their efficacy. Although several bnAbs bind to the conserved stem domain of HA, focusing the immune response to this conserved stem in the presence of the immunodominant, variable head domain of HA is challenging. We report the design of a thermotolerant, disulfide-free, and trimeric HA stem-fragment immunogen which mimics the native, prefusion conformation of HA and binds conformation specific bnAbs with high affinity. The immunogen elicited bnAbs that neutralized highly divergent group 1 (H1 and H5 subtypes) and 2 (H3 subtype) influenza virus strains in vitro. Stem immunogens designed from unmatched, highly drifted influenza strains conferred robust protection against a lethal heterologous A/Puerto Rico/8/34 virus challenge in vivo. Soluble, bacterial expression of such designed immunogens allows for rapid scale-up during pandemic outbreaks