Phasor-Quaternion Self-Organizing-Map-Based Ground Penetrating Radar Systems

Visualization by ground penetrating radar (GPR) systems has a wide demand in various application fields. Our conventional visualization method mainly extracts feature vectors based on the frequency and spatial correlation of scattering parameters and then uses complex-valued self-organizing maps (CSOM) in unsupervised grouping to achieve visualization. However, this method sometimes shows problems of unclear boundary and deformed shape of a detected object. In this article, we propose a novel algorithm, phasor-quaternion self-organizing map (PQSOM), based on the Poincare vectors combined with phase, which is organized in phasor-quaternion (PQ) form. By considering both the polarization state and the phase information as respective counterparts, we achieve a more accurate grouping result. Through visualization experiments of underground landmines, we find that, compared with the previous methods, the boundary clarity and the shape of objects are improved.