Advanced techniques for generating infrared (IR) scenes of a maritime environment for use in an imaging infrared (IIR) Anti-Ship Cruise Missile (ASCM) are discussed. The enhancements include the incorporation of a cluttered sea surface using an improved version of the Mermelstein sea-surface model. The US Naval Research Laboratory has implemented this capability for generating uncorrelated clutter into IR scenes for use in the CRUISE_Missiles ASCM model. These techniques for capturing the more complex features of the environment will become increasingly important as more low-observable (LO) ships, advanced imaging ASCMs and new IR decoy techniques are designed and deployed. This paper presents the design and implementation of a static clutter model, as well as a qualitative validation of the synthesized scenes based on field data.
A technique is developed for synthesizing a high spectral resolution IR ship signature image, for use in an imaging IR Anti-Ship Cruise Missile (ASCM) model, from an IR scene database provided by the ship signature model NTCS/ShipIR. This synthesized IR ship image is generated for use over ranges representative of an ASCM engagement. The technique presented focuses on the application of in-band averaged transmittance to the source ship signature as a means of reducing the spectral calculations required by the cruise missile model. In order to achieve this reduction in computation, while preserving the fidelity of the apparent ship signature, the idea of sub-banding is introduced. Sub-banding describes the manner in which the IR band is partitioned into smaller bandwidths, such that the error produced in the ship's average contrast radiance due to the use of in-band averaged transmittance is minimized over range. The difference between the average contrast radiance of an IR ship image generated using in-band averaging and the average contrast radiance of a spectrally generated IR ship image is the metric for this minimization. This choice is based on measured data collected from the recent NATO SIMVEX trial, which used high quality IR measurements of the CFAV Quest in an effort to refine the NTCS/ShipIR model. The technique is general and applicable to any band(s) of interest. Results are presented which verify that the use of in-band averaged transmittance over an IR band (3.5-5.0 μm), partitioned using three optimal sub-bands, produces an IR ship image with an average contrast radiance within the desired error bar of a spectrally generated ship image's average contrast radiance.