Nonlinear Temperature Mapping for Infrared-Based Landing Site Detection

This paper proposes a novel nonlinear temperature mapping algorithm for infrared sensors for landing field detection and relative positioning for integrity monitoring of an INS/SBAS navigation solution during landing approach. Traditional linear temperature mapping algorithms, which clip the temperature range to increase contrast, come at the cost of losing details at the remote ends of the temperature scale. The proposed algorithm does not clip the temperature range but uses parametrized nonlinear S-shaped mapping curves to increase contrast while also retaining details at the remote ends of the temperature range. The influence of the maximum curve gradient and inflection point temperature are investigated. The performance of the proposed algorithm is discussed using recorded flight-test data of landing approaches by fixed-wing as well as VTOL aircraft.