Environmental Objects for Authoring Procedural Scenes

International audienceWe propose a novel approach for authoring large scenes with automatic enhancement of objects to create geometric decoration details such as snow cover, icicles, fallen leaves, grass tufts or even trash. We introduce environmental objects that extend an input object geometry with a set of procedural effects that defines how the object reacts to the environment, and by a set of scalar fields that defines the influence of the object over of the environment. The user controls the scene by modifying environmental variables, such as temperature or humidity fields. The scene definition is hierarchical: objects can be grouped and their behaviours can be set at each level of the hierarchy. Our per object definition allows us to optimize and accelerate the effects computation, which also enables us to generate large scenes with many geometric details at a very high level of detail. In our implementation, a complex urban scene of 10 000 m², represented with details of less than 1 cm, can be locally modified and entirely regenerated in a few seconds

Biologically inspired simulation of livor mortis

We present a biologically motivated livor mortis simulation that is capable of modelling the colouration changes in skin caused by blood pooling after death. Our approach consists of a simulation of post mortem blood dynamics and a layered skin shader that is controlled by the haemoglobin and oxygen levels in blood. The object is represented by a layered data structure made of a triangle mesh for the skin and a tetrahedral mesh on which the blood dynamics are simulated. This allows us to simulate the skin discolouration caused by livor mortis, including early patchy appearance, fixation of hypostasis and pressure induced blanching. We demonstrate our approach on two different models and scenarios and compare the results to real world livor mortis photographic examples

When... not, ou le non-événement

Cette étude porte sur la possibilité qu’offre l’anglais de négativer une subordonnée temporelle introduite par “when” de telle façon qu’un événement se trouve situé temporellement par rapport à la négation d’un autre. On dégagera les implications de ce paradoxe : un non-événement est posé comme repère temporel ; quelque chose qui n’a pas lieu, qui est donc dépourvu d’existence, est néanmoins présenté comme se produisant à un moment donné et servant de déclencheur à un nouvel événement. L’explicitation du point de vue d’où est perçue la situation, en révélant la vraie portée de la négation (quelqu’un prend conscience que... ne... pas), montrera que le repère temporel est moins une “absence d’événement” que la perception d’un non-événemen

Simulating How Salt Decay Ages Buildings

International audienceSalt-based aging plays an important part in the realism of scenes featuring stone structures and monuments. A proposed model, based on physical behaviors and principles, replaces the simulation of complex physical formulations with ad hoc algorithms. It leads to plausible results, ultimately helping designers create aging patterns on affected objects

Simulating Atmospheric Pollution Weathering on Buildings

Interactions between polluted atmosphere and materials lead to an early aging of numerous buildings and monuments. This weathering process leads to important changes in appearance, from color blackening to smallscale geometric alterations: a black crust grows onto parts of affected surfaces, depending on the geometry of the object as well as on its environment. In this paper, we present a method to simulate this very important weathering process. Our method is physically inspired and provides full control to designers, keeping plausible results. First, specific polluted zones are detected according to their real physical classification. Then, the modifications of aspect of each zone are computed. Our results demonstrate that our model matches well the observed behavior of real-world monuments and buildings affected by atmospheric pollution

Interactive solar irradiance estimation in urban scenes

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Heat Transfer Simulation for Modeling Realistic Winter Sceneries

International audienceThis paper presents a physically based method for simulating the heat transfers between the different environmental elements to synthesize realistic winter sceneries. We simulate the snow fall over the ground, as well as the conductive, convective and radiative thermal transfers using a finite volume method according to the variations of air and dew point temperatures, the amount of snow, cloud cover and day-night cycles. Our approach takes into account phase changes such as snow melting into water or water freezing into ice

Calibrating low-cost structured-light 3D sensors

Consumer-grade RGB-D cameras are widely accessible, but they suffer from a lack of accuracy when compared to professional-grade 3D scanning solutions. In this paper, we propose a new method for calibrating an Intel RealSense SR300 camera, adaptable to other structured light sensors. The method uses classical checkerboard calibration and a coordinate-measuring machine (CMM) based setup with a calibrating plane. It delivers better results than the manufacturers settings

Real-Time Solar Exposure Simulation in Complex Cities

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Weathering of Urban Scenes: challenges and possible solutions

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