Multispectral observations of the surf zone

Abstract

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 measurements in the surf zone

“…The surf zone index (SZI) is discussed in detail in Gilbert (2003) and is summarized in Schoonmaker et al (2003). The basis of the index is the concept of contrast and, in general, the SZI is the contrast transmittance of the surf zone from the depth of a potential target.…”

“…where Y(z) is the SZI for a target at depth z, and C z is the apparent contrast of the target at depth z as seen by the sensor and C 0 is the inherent contrast of the target against the expected background. In Schoonmaker et al (2003) the SZI is measured using the apparent and inherent contrasts of targets deployed in the surf at Duck, NC. In this paper the analysis is expanded to predict the probability that the SZI exceeds a given critical value (Y c ) throughout the surf zone or P |Y>Yc|.…”

Environmental factors impacting the performance of airborne lidar sensors in the surf zone

“…The Navy is developing sensors for optical detection of mines in the surf zone [1,2,3,4,5]. The performance of these sensors is expected to be largely determined by environmental factors.…”

“…In September 2002 several tests [2,3,4,6] relevant to the performance of optical sensors in the surf zone, beach zone, and very shallow water were conducted at the Army Corp of Engineers Field Research Facility (FRF) in Duck, North Carolina. These tests were sponsored by ONR.…”