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The Taub Faculty of Computer Science Events and Talks

Pixel Club: 3D Shape from Underwater Flickering Illumination
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Yohay Swirski (EE, Technion)
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Tuesday, 23.07.2013, 11:30
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EE Meyer Building 1061
The underwater environment is challenging for computer vision tasks. Poor visibility, geometrical distortions and spatio-temporal varying illumination are some of the physical sources of these challenges. Spatio-temporal varying illumination is created by refraction of light through the wavy water surface and is known as underwater flicker. In past studies, flicker has often been considered to be an undesired effect, which degrades the quality of images. In contrast, this research shows that flicker can actually be useful for underwater stereo vision. The temporal radiance variations due to flicker are unique to each object point, thus disambiguating the correspondence, using simple temporal calculations. This process is enhanced by compounding the spatial variability and a smoothness constraint. This is done using a variational formulation for multi-frame stereo.

Furthermore, we generalize this approach for a free-moving stereo camera rig. This derives dense 3D structure, estimation of the rig motion, deflickering and descattering of underwater scenes, in addition to estimation of the water attenuation coefficients. The entire research is demonstrated by underwater in-situ field experiments and in a lab.

A PhD research under the supervision of Prof. Yoav Y. Schechner.