The visual detection of vehicles and personnel depend upon a number of factors: reflected/emitted color (photometry) contrast (spectral resolution), shapes and motion. Optical polarization has not been used although its relative radar has been readily been accepted and applied. There are clear analogs between radar optics and light optics.
Walter G. Egan, Walter G. Egan,
"Detection of vehicles and personnel using polarization", Proc. SPIE 4133, Polarization Analysis, Measurement, and Remote Sensing III, (15 November 2000); doi: 10.1117/12.406630; https://doi.org/10.1117/12.406630