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The purpose of this paper is to present a new method for evaluation of 3D object shapes which are inside of different environments, and a direct visual contact is not possible. High resolution sensors could solve this kind of problem, mainly by inverse electromagnetic scattering using antenna arrays or synthetic apertures. A cheaper solution is to radiate acoustic field inside of the searched environment. The object detection is realized when the level of received signal exceeds a certain value. The object shape could be appreciated by analyze of 10 consecutive resonant frequencies. Spectral distribution of the resonant frequencies represents the object "signature", and it is related to spatial object dimensions. For a given object, this spectral distribution could show how large the object is, in what way the outer surface is smooth or rough or how large the roughness is. The simulation results for three types of objects: pyramid, sphere, and ellipsoid cavities, smooth and rough are presented. Two roughnesses were selected for each object. The resonant frequencies of different objects could be stored and used for medical application (for instance, diagnosis of a tissue whether it is benign or malignant), mine detection buried in ground or evaluation of the different substances filling up the buried objects. |
