Extensions of the U.S. Night Vision Laboratory static performance model for thermal viewing systems on structural targets and backgrounds in cluttered scenes

摘要

Abstract: The search procedure and target acquisition in cluttered scenes are highly dependent on the contrast between target and background, and the scene content. The latter varies widely from uniform displays of sky or sea to highly complex displays of mixed landscapes or urban areas. Generally, contrast should be defined within the limit of the geometrical resolution of the sensor system. Both target and background will be structured in respect of optical radiance or thermal emittance. Lillesaeter has presented a contrast definition allowing for structured as well as plain targets and backgrounds. It consists of two parts, area contrast and edge contrast, both of which are logarithmic functions of target/background radiance ratios. This contrast definition has been implemented in the Night Vision Laboratory (NVL) model to simulate acquisition of thermally structured targets in complex backgrounds. As far as the effect of clutter makes the task of discriminating the target from background more difficult, videosimulations have been used to correlate the NVL model to different levels of scene complexity. This paper presents the NDRE modification of the NVL model and gives some examples related to the efficiency of thermal camouflage. !5