BRDF:
Bidirectional Reflectance Distribution Function modeling improvement

Background In the defence area, the precise recognition and identification of target objects is mandatory regarding the outcome of an operation. Therefore, the furtivity of a military aircraft is most of the time one of the keypoint of its conception. The furtivity mainly depends on two elements: the form or 3D structure of the object and its coatings (which reduce the visibility of the warm parts). The furtivity of any object can be efficiently studied by physical simulation software, able to ease greatly the conception step, through the test of detectability of an object by sensors accordingly to its 3D structure and its coatings in many different meteorological conditions, as long as necessary. Yet, this kind of simulation supposes an efficient material characterization, which is necessary to assess properly the visible or infrared signature of any object in a synthetic environment. Two components of the physical characterization are relevant: the BRDF (bidirectional reflectance distribution function) and the Emissivity. Taking into account these kind of data enables to define specific coatings mapping able to reduce the signature of an object. Moreover, the validation of the simulation results is the most criticle point. Concerned by this skill area, the CELAR, one of the divisions of the French DGA, asked to OKTAL-SE to elaborate a methodology in visible and in infrared domains to define the proper solutions concerning the coating of flying objects. Projects objectives The main objective of the BRDF project is the improvement of the physical characterization of the SE-Workbench-IR through the taking account of the radiative caracterization of physical materials and the surface roughness, in order to model the optic reflectivity, enabling the study the impact of the point on the furtivity of various objects. More precisely, objectives are: Taking account more precisely the BRDF in the SE-Workbench-IR software Taking account the Emissivity of materials Taking account the roughness statistic of materials Develop the global illumination analysis through the Photon Mapping method Achievements Physical models generation (MWIR and LWIR spectral models examination with SE-PHYSICAL-MODELER tool, models experiment with measurement simulation Enhancement of the optical reflectivity modelling by SE-Workbench-IR

Customer DGA/CELAR

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