Modélisation et simulation des propriétés radiatives des sources lumineuses

Abstract : The physical precision of simulations which permit the realistic visualization of a given geometric environnement depends on two factors: the precision of the physical model which describes the radiative properties of light sources (emittance) and surface (reflectance) of this environnement, and the precision of light propagation calculations between these surfaces. The work of my thesis presented here consists of defining a model for light source which permits the simulation of complex lighting system. This model takes into account any arbitrary type of spectral distributions (continuous or non-continuous) and spatial distributions (uniform or non-uniform) .- In image synthesis technology today, the spectral characteristics of light sources are still often modelized in the RGB colorimetric system. This colorimetric system does not allow us to obtain precise simulations from given spectral data because it depends on display device. Methods have been recently developed to sample the wavelength domain and calculate the light propagation from this set of samplesj which however, do not permit the treatment of complex spectral characteristics. To solve this problem, we have proposed a method based upon preliminary analyse of spectrums utilized. This method removed certain constraints imposed by actual methods. -To take into account the spatial energy distribution of light sources in the illumination calculations, classical methods assume that the distributions are uniform. This simplification is unjust since artificial sources never have a uniform spatial energy distribution. To simulate this type of light sources, models based upon gonio-photometric diagram provided by the manufacturers of lighting systems have been developed. However, these methods introduce an important error in the surface illumination calculation when sources are dose to the surface. This is why we have proposed a new method founded upon a precise geometric modelization of a light fixture (lamp, reflector, lens) and consider the source like a sub-domain of this environnement which emits energy by an intermediate interface zone. Inside this sub-domain, the spatial energy distribution is calculated on the interface zone by using a projection method. The two methods (spatial and spectral distributions) actually proposed in this thesis have been experimented and will be transferred into the industrial domain further developement.
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Theses
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http://docnum.univ-lorraine.fr/prive/SCD_T_1996_0004_DEVILLE.pdf
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https://hal.univ-lorraine.fr/tel-01747247
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Submitted on : Thursday, March 29, 2018 - 10:55:40 AM
Last modification on : Tuesday, January 29, 2019 - 1:21:54 AM

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Pascal Deville. Modélisation et simulation des propriétés radiatives des sources lumineuses. Autre [cs.OH]. Université Henri Poincaré - Nancy 1, 1996. Français. ⟨NNT : 1996NAN10004⟩. ⟨tel-01747247⟩

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