Agenda

Filippo Bergamasco, DAIS

Abstract:
Stereo 3D reconstruction is continuously increasing its popularity in the study of medium to small-scale sea waves. In the recent past, different approaches have been proposed to reconstruct the space-time spectrum of the sea surface from synchronized stereo frames. Usually, the reconstruction is performed by first recovering a dense point cloud from stereo pairs and then by interpolating it into a regular grid to transform the data in frequency domain. Even considering state-of-the-art methods, it's unlikely to perform the first step in less than dozens of seconds, that can easily exceed a minute if we include the subsequent interpolation step. This will limit the applicability of stereo based wave analysis for all the approaches (like data assimilation) in which the time between the raw acquisition and the output of processed data is critical.

In this seminar, we introduce a new method to directly estimate the sea surface spectrum over time from a sequence of stereo frames. We exploit the frequency dispersion relation of gravity waves and the Non-uniform Fast Fourier Transform to continuously update the spectrum estimation given a sparse set of matching features between the two frames. This effectively combines the two aforementioned steps in a fast and effective way. Preliminary results show a performance gain of more than an order of magnitude while still keeping a reconstruction accuracy close to the current state-of-the-art approaches.