Retrieval of short ocean wave slope using polarimetric imaging

Abstract

We present a passive optical remote sensing technique for recovering shape information about a water surface, in the form of a two-dimensional slope map. The method, known as polarimetric slope sensing (PSS), uses the relationship between surface orientation and the change in polarization of reflected light to infer the instantaneous two-dimensional slope across the field-of-view of an imaging polarimeter. For unpolarized skylight, the polarization orientation and degree of linear polarization of the reflected skylight provide sufficient information to determine the local surface slope vectors. A controlled laboratory experiment was carried out in a wave tank with mechanically generated gravity waves. A second study was performed from a pier on the Hudson River, near Lamont-Doherty Earth Observatory. We demonstrated that the two-dimensional slope field of short gravity waves could be recovered accurately without interfering with the fluid dynamics of the air or water, and water surface features appear remarkably realistic. The combined field and laboratory results demonstrate that the polarimetric camera gives a robust characterization of the fine-scale surface wave features that are intrinsic to wind-driven air-sea interaction processes.

Polarized 3D: High-Quality Depth Sensing with Polarization Cues

“…Polarization cues are also widely used in computational imaging applications, such as separation of diffuse and specular reflections [30,49], dehazing of images [38], image mosaicing and panoramic stitching [39], illumination multiplexing [6] and camera [23,18] or display hardware [21]. In addition, polarization cues can be used to recover shape of translucent objects [5], shape of the ocean surface [46], or address scattering underwater [41].…”

Characterization of Sun Glitter Statistics in Ocean Video

“…Other forms of still imagery have been used to study glitter, including stereo photos [78][79][80][81][82][83][84][85][86] (as discussed by Jähne, Klinke, and Waas [87] and Monaldo and Kasevich [25]), polarimetric imagery [88], infrared imagery [89][90][91], satellite imagery [92][93][94][95], and other imagery types [96].…”

Method to reduce motion artifacts of sequential imaging polarimetry: long enough exposures minimize polarization blurs of wavy water surfaces

“…They used a fast-motorized rotating-analyser SeqIP, which minimized motion artefacts. Determination of ocean wave shapes [31] or oil detection on water [32] are further interesting water-surface-related applications of imaging polarimetry, although the latter utilizes SimIP.…”