title: Determining scale and sea state from water video.
abstract: In most image processing and computer vision applications, real-world scale can only be determined when calibration information is available. Dynamic scenes further complicate most situations. However, some types of dynamic scenes provide useful information that can be used to recover real-world scale. In this paper, we focus on ocean scenes and propose a method for finding sizes in real-world units and the sea state from an uncalibrated camera. Fourier transforms in the space and time dimensions yield spatial and temporal frequency spectra. For water waves, the dispersion relation defines a square relationship between the wavelength and period of a wave. Our method applies this dispersion relation to recover the real-world scale of an ocean sequence. The sea state--including the peak wavelength and period, the wind speed that generated the waves, and the wave heights--is also determined from the frequency spectrum of the sequence combined with stochastic oceanography models. The process is demonstrated on synthetic and real sequences, validating the results with known scene geometry. This has wide applications in port monitoring and coastal surveillance.
authors.affiliation: College of Engineering and Computer Science, University of Central Florida, Orlando 32816-2450, USA. lspencer@cs.ucf.edu
authors.forename: Lisa
authors.initials: L
authors.lastname: Spencer
authors.forename: Mubarak
authors.initials: M
authors.lastname: Shah
authors.forename: Ratan K
authors.initials: RK
authors.lastname: Guha
mesh_terms: D000465:Algorithms; D016000:Cluster Analysis; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D009792:Oceans and Seas; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014741:Video Recording / Q000379:methods*; D014867:Water; D014872:Water Movements
chemical_list: D014867:Water