Yohay Swirski (EE, Technion)
Tuesday, 23.7.2013, 11:30
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.