Validation of a CFAR vessel detection algorithm using known vessel locations

Abstract

The National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite, Data, and Information Service (NESDIS) is in the second year of a two-year demonstration of Synthetic Aperture Radar (SAR) derived products called the Alaska SAR Demonstration (AKDEMO). This demonstration provides near real-time SAR data and derived products, including wind images and vectors, hard target locations, along with ancillary data, to specific users in the government community. One of the derived products are vessel positions obtained from a constant false alarm rate (CFAR) vessel detection algorithm developed by Veridian ERIM. This algorithm has been tested and validated to maximize the number of ships found while minimizing the number or false alarms on one SAR image of the Red King Crab fishery in Bristol Bay on October 18, 1999. This resulted in using a detection statistic threshold of about 5.5, depending on image resolution used. Until now, this validation has been done with only general knowledge of fishing fleet size and location, but no in situ vessel information. During the Red King Crab Fishery in Bristol Bay in October 2000, twenty-one Alaska Department of Fish and Game fishery observers recorded the position of the vessels they occupied (and sometimes the wind speed), during two ScanSAR overpasses on October 18 and 19, 2000. These ScanSAR passes, with a width of 480 km, cover the region of the fishery and many of the vessels with recorded positions. This paper presents the results of a validation of the SAR vessel detection algorithm using these observer reported vessel positions along with information on vessel size and local wind speed.