This PDF file contains the front matter associated with SPIE Proceedings Volume 6615, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Over the past year an index has been defined which quantifies the surf zone with respect to an electro-optical (EO) system's ability to find targets. The purpose of this index is to both normalize the EO Mine Counter Measure (MCM) systems performance expectations to the environment in which it is tested and to assess the value of its performance in an operational environment. For example, if a given system has a Probability of Detection (P-D) requirement of 90% in a clear water surf zone and is tested in murky waters the surf zone index of the murky water is used to determine what PD is required in the murky water to yield the 90% PD clear water requirement. The surf zone index is defined in this paper and expanded from the deterministic contrast transmittance as reported in earlier papers((1)) to a probabilistic approach. Examples of how to measure the index using readily available low cost spectral imagers such as PAR Government Systems Corporation's Mission Adaptable Narrowband Tunable Imaging Spectrometer (MANTIS) system are given. Finally, the surf zone index usage is discussed and demonstrated.

Airborne multispectral imagery was collected over various targets on the beach and in the water in an attempt to characterize the surf zone environment with respect to electro-optical system capabilities and to assess the utility of very low cost, small multispectral systems in mine counter measures (MCM) and intelligence, surveillance and reconnaissance applications. The data was collected by PAR Government Systems Corporation (PGSC) at the Army Corps of Engineers Field Research Facility at Duck North Carolina and on the beaches of Camp Pendleton Marine Corps Base in Southern California. PGSC flew the first two of its MANTIS (Mission Adaptable Narrowband Tunable Imaging Sensor) systems. Both MANTIS systems were flown in an IR-red-green-blue (700, 600, 550, 480 nm) configuration from altitudes ranging from 200 to 700 meters. Data collected has been lightly analyzed and a surf zone index (SZI) defined and calculated. This index allows mine hunting system performance measurements in the surf zone to be normalized by environmental conditions. The SZI takes into account water clarity, wave energy, and foam persistence.

Multispectral and hyperspectral sensors are being used for remote sensing and imaging of ocean waters. Many applications require the compression of hyperspectral data to achieve real-time transmission or exploitation. Hyperspectral data compression or reduction has been accomplished using techniques based upon principal component analysis or linear unmixing, Alternatively, data compression (reduction) may be performed by band selection, or band selection may be preliminary to either of the other compression techniques. Band selection also has implications for sensor design and the stability of estimates of processing parameters. In this study, we address the question of which bands are the most efficacious for imaging submerged objects, such as whales, using an anomaly detector, or a matched filter. Bands are selected by optimizing a detection criterion subject to a constraint on the number of bands. The technique is applied to five hyperspectral data sets, and the optimum bandwidths and centers are determined. The loss in performance from selecting reduced numbers of bands is tabulated and the need for adaptively selecting reduced numbers of bands is demonstrated.

Abstract : A method based on a theory of experimental Optimal Design (OD) was developed in Russia to select the best combination of wavelengths so an optically remote spectral sensor may optimally estimate oceanic chlorophyll concentration. It gives the number of spectral bands, their center wavelength, and each band's spectral width to make the best estimate of chlorophyll concentration in a fixed observation time. A hyperspectral sensor is convenient because it eliminates the need for variable optical filters. An ideal sensor would have an infinite number of infinitesimally narrow spectral bands. Optimal designs are given for both ideal and real sensors. The designs were computed using ocean radiance spectra simulated by a Monte Carlo model for a range of chlorophyll concentrations. The computed OD was tested for robustness over a wide range of experimental conditions. The methods of color index and principal component analysis were also applied. The optimal design method gives more accurate chlorophyll estimates.

In this paper, we describe an experiment to measure the point spread function (PSF) of Arctic ice that was conducted by personnel of the Naval Ocean Systems Center in 1985. SRI International designed and developed the instrumentation. In April, data were collected on refrozen leads in pack ice concentrated near the Beaufort Gyre. The location was about 200 miles from the North Pole at approximately 86 degrees north and 88 degrees west. PSF measurements were made with a Hasselblad camera and a pulsed Lambertian (cosine) source gated to the camera. Recently, SRI digitized the film data with a charge-coupled device (CCD) camera and performed a digital analysis of the images. Results from two sites of new and first- year ice, 0.66 m and 2.1 m thick, respectively, are presented. Because of the strong multiple scattering by sea ice, and the limited area of the ice surface that could be imaged by the camera, the data obtained only partially characterize the PSF of the ice. The paper concludes with suggestions for improving future sea ice PSF measurements.

The airborne lidar detection and cross-sectional mapping of submerged oceanic scattering layers are reported. The field experiment was conducted in the Atlantic Ocean southeast of Assateague Island, VA. NASA's Airborne Oceanographic Lidar was operated in the bathymetric mode to acquire on-wavelength 532-nm depth-resolved backscatter signals from shelf/slope waters. Unwanted laser pulse reflection from the airwater interface was minimized by spatial filtering and off-nadir operation. The presence of thermal stratification over the shelf was verified by the deployment of airborne expendable bathythermographs. Optical beam transmission measurements acquired from a surface truthing vessel indicated the presence of a layer of turbid water near the sea floor over the inner portion of the shelf.

Recent interest in the Arctic has led to the application of underwater irradiance measurement techniques to the determination of sea ice optical properties. Both a theoretical model of the bulk optical properties and in-situ instrumentation for the measurement of these properties was developed at the University of Washington in support of field measurements in the Marginal Ice Zone (MIZ). In order to extend the existing data base to higher latitudes and evaluate the technique for making optical measurements in this environment, the authors participated in a short exercise in the Arctic during April 1985, using University of Washington developed instruments. During a period of three weeks, numerous measurements of the spectral attenuation coefficient, kice, and albedo, rice, were made in refrozen leads of first year ice and new sea ice near the coordinates 86 degrees north and 88 degrees west. Ice thicknesses ranged from 30 to 300 cm. In addition to the optical properties, cores were taken to photograph ice crystal structure and measure the temperature profile. A description of the ice optical property measurement techniques and instrumentation is given. In addition to field measurements of the bulk optical properties of young ice at very low temperatures, data was obtained on the optical properties of the near surface water found in the higher Arctic latitudes during April. Recommendations are made for further field measurements and the use of models in data interpretation.

The continuous measurement of underwater light attenuation was investigated as a means of estimating chlorophyll distributions in Southern California coastal waters. In contrast to previous studies at other locales, depth profiles showed that the volume attenuation coefficient (a) covaried nonlinearly with chlorophyll a fluorescence. However, when measured over time at a fixed depth a and chlorophyll a fluorescence were observed to be linearly related. Results are consistent with a model that considers contributions to a from nonfluorescing particles whose distributions are influenced by thermal stratification of the water column.

By "optical turbulence" is meant small inhomogeneities in the index of refraction of seawater, their origins, and the effects they have on underwater optical systems. For most conventional underwater photographic and TV imaging systems as normally used, these effects are negligible most of the time-only under exceptional circumstances do they make an appreciable difference. However, they become a more significant factor as more sophisticated imaging systems are constructed that must function over longer ranges with high resolution.

A study involving polarization phenonema conducted at Lake Winni-pesaukee, New Hampshire, during the summer of 1965 caused one of the authors to think of the possible application of polarization techniques to underwater visibility range and contrast improvement. As a result, a series of tests was conducted at the U. S. Naval Ordnance Test Station (NOTS) Pasadena Annex Morris Dam facility in April 1966.