Finding physically motivated classification features using finite element models.

Finite element models (FEMs) for simple shapes such as spheres, cylinders and pipes can be used to uncover potential features for classification by sonar systems. Analyses were conducted of the simulated, bistatic returns over a wide range of aspects using FEMs for a solid steel cylinder and a cement pipe all in free space. Salient characteristics noted in this way were then sought in field data collected from the same or similar objects during the SAX04 experiment and two other data collections conducted in a test pond at the Naval Surface Warfare Center in Panama City, Florida. Characteristics robust enough to appear in both simulated data and field data are candidates to serve as classification features for similarly shaped objects. It is found that FEMs can provide important pointers to classification features that are closely tied to the physics of reflection. As such, the variability of these features in the face of object burial and multipath can be more easily assessed than statistical spectral fe...