Infrared ship signature prediction, model validation and sky radiance

The increased interest during the last decade in the infrared signature of (new) ships results in a clear need of validated infrared signature prediction codes. This paper presents the results of comparing an in-house developed signature prediction code with measurements made in the 3-5 um band in both clear-sky and overcast conditions. During...

Conspicuity and identifiability: efficient calibration tools for synthetic imagery

We argue that visual conspicuity and identifiability are two efficient task-related measures that can be deployed to calibrate synthetic imagery that is intended to be used for human visual search and detection tasks. The conspicuity of a target is operationally defined as the region around the center of the visual field where the target is...

Ship exhaust gas plume cooling

The exhaust gas plume is an important and sometimes dominating contributor to the infrared signature of ships. Suppression of the infrared ship signatures has been studied by TNO for the Royal Netherlands Navy over considerable time. This study deals with the suppression effects, which can be achieved using a spray of cold water in the inner...

Electro-optical missile plume detection

Detection of dim point targets in cluttered maritime backgrounds through multisensor image fusion

Multispectral IR imaging techniques are frequently deployed in maritime operations, for instance to detect floating mines or to find small dinghies and swimmers during search and rescue operations. However, maritime backgrounds usually contain a large amount of clutter that severely hampers the detection of dim point targets. Here we present a...

Human search with a limited Field of View: the effect of scanning parameters and scene content

In order to find an optimal scanning strategy we determined the relationship between search performance and several scanning- and scene parameters in human observer experiments. The observers searched with a limited field of view (FOV) through a large search sector for a target (a camouflaged person) on a heath. From trial to trial the target...

Aerosol plumes in a coastal environment revealed by lidar

A scanning backscatter lidar, operating at a wavelength of 1.06 um, was used to measure the volume backscatter coefficient of coastal aerosol at the Mace Head Research Station on the west coast of Ireland during the PARFORCE experiments in September 1998 and June 1999. Lidar measurements under a fixed elevation angle at fixed time intervals...

ARTEAM - Advanced ray tracing with earth atmospheric models

The Advanced Ray Tracing with Earth Atmospheric Models (ARTEAM) aims at a description of the electro-optical propagation environment in the marine atmospheric surface layer. For given meteorological conditions, the model evaluates height- and range-resolved transmission losses, refraction and turbulence effects. These results are subsequently...

Infrared polarisation measurements of targets and backgrounds in a marine environment

The infrared (IR) radiation emitted or reflected in an off-normal direction from a smooth surface is partially polarised. This principle can be used for enhanced discrimination of targets from backgrounds in a marine environment. It has been shown that (man-made) targets do not demonstrate a pronounced polarisation effect when observed from near...

From hyperspectral imaging to dedicated sensors

Hyper spectral imaging is a technique that obtains a two-dimensional image of a scene, while for each pixel a spectrum is recorded. Hyper spectral imaging systems can be very powerful at extracting information by using the spectral information in addition to the more conventional information extraction algorithms based on the spatial information...

Modeling multi-spectral imagery data with NIRATAM v3.1 and NPLUME v1.6

Spectral imagery data (2.0 to 5.4 micrometer) was collected of plumes of ships by the NATO Special Working Group 4. It provides the means to study the signature of a target spectrally, spatially, and temporally. This experimental data has been used to validate the infrared signature of the plume of a ship as computed by NATO's flow-field program...

Maritime Infrared Background Clutter

The detection of small targets in maritime infrared surveillance is hampered by the presence of clutter. Sea surface structure, reflection and emission changes related to incident angle variations and surface effects are standard features governing the clutter behavior. Also special effects as sun glint an horizon effects play an important role...

Multispectral maritime background and clutter effects on small surface target detection

This paper concerns multispectral backgrounds and clutter as they hamper the detection process of small surface targets. The variability of target contrast is shown for a number of meteorological conditions in the various spectral bands, for which new types of sensors have become available. It is shown that simultaneous framing with pixel co...

Evaluation of infrared signature suppression of ships

Reduction of the infrared signature of warships helps to increase their survivability. Two methods to reduce the infrared signature are discussed: the cooling of exhaust gases and the application of low emissivity paint. The infrared signature of a generic frigate has been calculated with and without signature reduction. The signature values are...

Experimental evaluation of thermal camouflage effectiveness

The detectability of a target in the infrared spectral region is determined by differences between the radiative signatures of the target and the local background. This implies that both, the difference in surface temperature and emissivity ΔT resp. Δε and the distribution of these differences over the target area and the background, are of...

Infrared clutter measurements of marine backgrounds

Observations in the infrared wavelength band between 8 and 12 μm of sea backgrounds have been recorded with a CCIR compatible imager for a large number of sea states (0 - 6). Recordings took place in coastal areas as well as on open seas. The behavior of clutter in the infrared data was analyzed in space and in time. Clutter values are analyzed...