Edge detection applied to satellite imagery of the oceans

A computer edge-detection algorithm for automatic delineation of mesoscale structure in digital satellite IR (infrared) images of the ocean is developed. The popular derivative-based edge operators are shown to be too sensitive to edge fine-structure and to weak gradients to be useful in this application. The edge-detection algorithm is based on the gray level cooccurrence matrix (GLC), which is commonly used in image texture analysis. The cluster shade texture measure derived from the GLC matrix is found to be an excellent edge detector that exhibits the characteristic of fine-structure rejection while retaining edge sharpness. This characteristic is highly desirable for analyzing oceanographic satellite images     

Comparative study of two recent edge-detection algorithms designedto process sea-surface temperature fields

Two algorithms used for the detection of fronts in satellite-derived sea-surface temperature fields are compared. The two algorithms produced surprisingly comparable results considering the substantial differences in the two approaches: multilevel (Algorithm 1) versus locally based (Algorithm 2). Algorithm 1 offers the advantage of shorter run times. Algorithm 2 can be made faster if one is willing to accept less reliable edge detection. Algorithm 1 also offers the advantage of being adaptive and therefore automatic in its application to different data sets. However, when direct control with regard to detection of the edges is demanded, Algorithm 2 contains two tunable parameters to select the smoothness and the strength of edges, while Algorithm 1 as presently coded does not     

A longitudinal study of Mycoplasma pneumoniae: infections in Navy recruits by isolation and seroepidemiology

A longitudinal serologic study of M. pneumoniae infections in two recruit training centers with grossly different climates showed that the frequency of this infection peaks in the late summer-early fall and to a lesser degree in the spring at both training centers. Seroconversions (four-fold or greater increase in titer) were as high as 45-57% in some recruit companies during the late summer peak. M. pneumoniae isolations from men admitted to the dispensary or hospital with pneumonia during the major peak season were as high as 32%. While M. pneumoniae infections are not generally life-threatening, the high incidence of infections observed in personnel during recruit training is of major concern and warrants consideration of effective control measures.     

Circle detection for extracting eddy size and position fromsatellite imagery of the ocean

Evaluates the ability of several circle detectors to define the size and position of warm and cold eddies in oceanographic satellite imagery. The Advanced Very High Resolution Radiometer channel 4 (10.3-11.3 μm) or sea surface temperature test images are reduced to binary edge images. Six different circle detectors are then applied to the edge images. The automated results are compared to eddies defined by a trained analyst