Small flying robots can perform landing maneuvers using bio-inspired optical flow by maintaining a constant divergence. However, optical flow is typically estimated from frame sequences recorded by standard miniature cameras. This requires processing full images on-board, limiting the update rate of divergence measurements, and thus the speed of the control loop and the robot. Event-based camer...

This paper describes procedures for obtaining a reliable and dense optical flow from image sequences taken by a television (TV) camera mounted on a car moving in usual outdoor scenarios. The optical flow can be computed from these image sequences by using several techniques. Differential techniques to compute the optical flow do not provide adequate results, because of a poor texture in images ...

In this paper we propose a variational model for joint optical flow and occlusion estimation. Our work stems from the optical flow method based on a TV-L approach and incorporates information that allows to detect occlusions. This information is based on the divergence of the flow and the proposed energy favors the location of occlusions on regions where this divergence is negative. Assuming th...

In this paper, we propose an original approach for content-based video indexing and retrieval. It relies on the tracking of entities of interest and the analysis of their apparent motion. To characterize the dynamic information attached to these objects, we consider a probabilistic modeling of the spatio-temporal distribution of the optic flow field computed within the tracked area after cancel...

[1] The influence of mixed‐phase stratiform clouds on the surface shortwave irradiance is examined using unique spectral shortwave irradiance measurements made during the Indirect and Semi‐Direct Aerosol Campaign (ISDAC), supported by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. An Analytical Spectral Devices (ASD, Inc.) spectroradiometer measured downwelling s...

Changes in cardiac deformation patterns are correlated with cardiac pathologies. Deformation can be extracted from tagging Magnetic Resonance Imaging (tMRI) using Optical Flow (OF) techniques. For applications of OF in a clinical setting it is important to assess to what extent the performance of a particular OF method is stable across different clinical acquisition artifacts. This paper presen...

In this paper, we presen t an observation model based on the Lucas and Kanade algorithm for computing optical ow, to trac k objects using particle lter algorithms. Although optical ow information enables us to know the displacement of objects present in a scene, it cannot be used directly to displace an object model since ow calculation techniques lack the necessary precision. In view of the fa...

We consider the problem of obtaining the 3D trajectory of a ball from a sequence of images taken with a camera which is possibly rotating and zooming (but not translating). Techniques are developed to compute the component of image motion of the ball due to camera rotation and zoom, using optic flow. The 3D location of the ball in each frame of the sequence is then determined using a novel geom...

Light-light switching typically requires strong nonlinearity where intense laser fields route and direct data flows of weak power, leading to a high power consumption that limits its practical use. Here we report an experimental demonstration of a metawaveguide that operates exactly in the opposite way in a linear regime, where an intense laser field is interferometrically manipulated on demand...

In this paper, we present a technique for object tracking in image sequences, which includes a novel velocity field estimation for vertex locations of a polygon. In this approach, after capturing boundaries of an object by a polygon from the first few frames of the image sequence, both the spatial segmentation and motion segmentation of a polygonal object can be achieved quickly by involving on...