Acoustic simulation related publications
The following publications have been made by the OKTAL-SE research and development team in relations
with reseach institutes in France and in Europe.
SPIE 2004
The simulation workshop CHORALE of the French DGA is used by government services and industrial companies for weapon system validation and qualification trials in the infrared domain, and detection of moving vehicles in the acoustic domain.
Recently, acoustic simulation tests were performed on the 3D geometrical database of the DGA/DCE/ETBS proving ground. Results have been compared to the acoustic measurements of the NATO-TG25 trials.
This article describes the trials, the modeling of the 3D geometrical database and the comparison between acoustic simulation results and measurements.
The 3D scene is described by a set of polygons. Each polygon is characterized by its acoustic resistivity or its complex impedance. Sound sources are associated with moving vehicles and are characterized by their spectra and directivities. A microphone sensor is defined by its position, its frequency band and its directivity.
For each trial, atmospheric profiles (air temperature, pressure and humidity according to altitude), trajectories and sound spectrum of moving objects were measured. These data were used to prepare the scenario for the acoustic simulation.
CFA 2004
The simulation workshop CHORALE (CHamp de bataille Optronique Radar Acoustique simuLE) is used by government services and industrial companies for multisensor simulations in realistic 3D virtual scenes (visible, infrared, EM and acoustic simulations). The need is, for example, the simulation of the multi sensor detection of moving vehicles in 3D scenes. This article describes the acoustic model in CHORALE and the validation tests based on the results of international acoustic detection experiment NATO/TG25.
SPIE 2003
The simulation workshop CHORALE developed in collaboration with OKTAL-SE company for the French MoD is used by government services and industrial companies for weapon system validation and qualification trials in the infrared domain. The main operational reference for CHORALE is the assessment of the infrared guidance system of the Storm Shadow missile French version, called Scalp. The use of CHORALE workshop is now extended to the acoustic domain. The main objective is the simulation of the detection of moving vehicles in realistic 3D virtual scenes.
This article briefly describes the acoustic model in CHORALE.
The 3D scene is described by a set of polygons. Each polygon is characterized by its acoustic resistivity or its complex impedance. Sound sources are associated with moving vehicles and are characterized by their spectra and directivities. A microphone sensor is defined by its position, its frequency band and its sensitivity.
The purpose of the acoustic simulation is to calculate the incoming acoustic pressure on microphone sensors. CHORALE is based on a generic ray tracing kernel. This kernel possesses original capabilities: computation time is nearly independent on the scene complexity, especially the number of polygons, databases are enhanced with precise physical data, special mechanisms of antialiasing have been developed that enable to manage very accurate details. The ray tracer takes into account the wave geometrical divergence and the atmospheric transmission. The sound wave refraction is simulated and rays cast in the 3D scene are curved according to air temperature gradient. Finally, sound diffraction by edges (hill, wall, …) is also taken into account.