Coherent Integration of Optical Flow for Track-Before-Detect Radar Detection

The detection of small and dim targets under low signal-to-noise ratio (SNR) circumstances is a commonly encountered yet challenging endeavour in radar signal processing. The standard approach to deal with undesirable background conditions involves coherent processing and integration with subsequent detection directly applied to the radar signals. However, optical flow, a widespread visual tracking method, has rarely been used in this context. In this paper, we address the issue of radar target detection in low SNR scenarios by employing optical flow on radar images. This work focuses on the divergence of the optical flow vector field, utilising a novel approach of coherently integrating consecutive flow fields calculated against a homogeneous reference plane. The proposed methodology allows for more robust target identification and thus a precise initialisation of tracking systems. To validate and demonstrate the benefits of the proposed approach, simulations are conducted and discussed.