A scale-space aproach to nonlocal optical flow calculations

[EN] This paper presents an interpretation of a classic optical flow method by Nagel and Enkelmann as a tensor-driven anisotropic diffusion approach in digital image analysis. We introduce an improvement into the model formulation, and we establish well-posedness results for the resulting system of parabolic partial differential equations. Our method avoids linearizations in the optical flow constraint, and it can recover displacement fields which are far beyond the typical one-pixel limits that are characteristic for many differential methods for optical flow recovery. A robust numerical scheme is presented in detail. We avoid convergence to irrelevant local minima by embedding our method into a linear scale-space framework and using a focusing strategy from coarse to fine scales. The high accuracy of the proposed method is demonstrated by means of a synthetic and a real-world image sequence.

Henry Melson Stommel : from pionner to clasic

[EN] Stommel has been the most important physicist oceanographer of the second half of the XX century. Builder, to a great extent, of the present Dynamical Oceanography. He contributed to the transformation of the Oceanography from a sort of appendix of the studies of the Atmosphere to a new specialty of Geophysics. After graduating in Astronomy in Yale in 1942 he started his research participating in the WWII effort, collaborating together with many other future oceanographers, in support of the USA Navy. Research that was carried out in the Woods Hole Oceanographic Institution (WHOI). Between 1959 and 1978 he was professor of oceanography in Harvard U. first, and later in the Massachusetts Institute of Technology, returning to WHOI where he stayed until his death. Stommel established important and fundamental theories on the ocean global circulation and studied many other oceanographic phenomena. This theoretical activity he combined with not a less important observational one. He received many awards and hhonors, including the Craadford prize, equivalent to the Nobel in Geosciences.