A method to extract the Quaternion Ship Domain parameters from AIS data

The ship domain concept is of great interest for ship traffic modelling, risk assessment and intelligent collision avoidance. The paper proposes and applies a method to define AIS data-based empirical polygonal ship domains, based on traffic density matrices that are derived around each reference ship from an AIS dataset. A modified Quaternion Ship Domain allowing for different shapes for each quadrant is proposed, which results in a better fitting to the empirical domain. The parameters of Quaternion Ship Domains that best fit the empirical polygonal domains are determined for cargo ships and tankers of different lengths. Violations of the Quaternion Ship Domain are then used as an indicator of collision risk that is graphically represented in the study area, providing important information to support maritime traffic monitoring and control tasks. • Extraction of empirical ship safety domains from AIS data. • Fitting Quaternion Ship Domain to polygonal ship domain. • Quaternion Ship Domain with different quadrant shape parameters. • Collision risk perception related to the number of violations of a ship domain.