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Concept

Secteur sphérique

Publications associées (21)

Two-dimensional modelling of transient capillary driven damped micro-oscillations and self-alignment of objects in microassembly

François Gallaire

In the fields of microgripping and microassembly, the self-alignment motion of a solid micro-object linked by a liquid meniscus to a substrate or a tool is an inexpensive way to overcome the current limitations of the assembly processes at microscale by ge ...

Cambridge University Press2021

Spherical cap harmonic analysis (SCHA) for characterising the morphology of rough surface patches

Katrin Beyer, Mahmoud S. M. Shaqfa

We use spherical cap harmonic (SCH) basis functions to analyse and reconstruct the morphology of scanned genus-0 rough surface patches with open edges. We first develop a novel one-to-one conformal mapping algorithm with minimal area distortion for paramet ...

2021

Infinitesimal asphericity changes the universality of the jamming transition

Matthieu Wyart

The jamming transition of non-spherical particles is fundamentally different from the spherical case. Non-spherical particles are hypostatic at their jamming points, while isostaticity is ensured in the case of the jamming of spherical particles. This stru ...

IOP PUBLISHING LTD2020

Graph-based regularization of inverse problems in imaging

Mattia Rossi

As of today, the extension of the human visual capabilities to machines remains both a cornerstone and an open challenge in the attempt to develop intelligent systems. On the one hand, the development of more and more sophisticated imaging devices, capable ...

EPFL2020

Spherical Clustering of Users Navigating 360° Content

Pascal Frossard, Laura Toni, Francesca De Simone

In Virtual Reality (VR) applications, understanding how users explore the omnidirectional content is important to optimize content creation, to develop user-centric services, or even to detect disorders in medical applications. Clustering users based on th ...

IEEE2019

Specification of aspherical surfaces used as refractive elements in micro-optical systems

Toralf Scharf, Wilfried Noell, Jeremy Béguelin

The optical performance of refractive plano-convex microlenses is mainly related to the quality of their (a)spherical surface. An efficient tolerancing of this surface is a key step towards the manufacturing of high quality microlenses. However, we demonst ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Graph-Based Detection of Seams In 360-Degree Images

Pascal Frossard, Francesca De Simone, Roberto Gerson De Albuquerque Azevedo, Sohyeong Kim

In this paper, we propose an algorithm to detect a specific kind of distortions, referred to as seams, which commonly occur when a 360-degree image is represented in planar domain by projecting the sphere to a polyhedron, e.g, via the Cube Map (CM) project ...

2019

Rayleigh-Taylor instability under a spherical substrate

François Gallaire, Gioele Mariano Nicolò Balestra

We investigate the Rayleigh-Taylor instability of a thin viscous film coating the inside of a spherical substrate. The aim of this work is to find and characterize the instability pattern in this spherical geometry. In contrast to the Rayleigh-Taylor insta ...

2018

Rate Distortion Optimized Graph Partitioning for Omnidirectional Image Coding

Pascal Frossard, Francesca De Simone, Thomas Maugey

Omnidirectional images are spherical signals captured by cameras with 360-degree field of view. In order to be compressed using existing encoders, these signals are mapped to planar domain. A commonly used planar representation is the equirectangular one, ...

IEEE COMPUTER SOC2018

Deformable block based motion estimation in omnidirectional image sequences

Pascal Frossard, Francesca De Simone

This paper presents an extension of block-based motion estimation for omnidirectional videos, based on a camera and translational object motion model that accounts for the spherical geometry of the imaging system. We use this model to design a new algorith ...

2017

Sampling and Exact Reconstruction of Pulses with Variable Width

Martin Vetterli, Adam James Scholefield, Gilles Baechler, Loïc Arnaud Baboulaz

Recent sampling results enable the reconstruction of signals composed of streams of fixed-shaped pulses. These results have found applications in topics as varied as channel estimation, biomedical imaging and radio astronomy. However, in many real signals, ...

Institute of Electrical and Electronics Engineers2017

3D galaxy clustering with future wide-field surveys: Advantages of a spherical Fourier-Bessel analysis

Anaïs Marie Rassat

Context. Upcoming spectroscopic galaxy surveys are extremely promising to help in addressing the major challenges of cosmology, in particular in understanding the nature of the dark universe. The strength of these surveys, naturally described in spherical ...

EDP Sciences2015

Reconfigurable Forward Homography Estimation System for Real-Time Applications

Yusuf Leblebici, Vladan Popovic

Image processing and computer vision algorithms extensively use projections, such as homography, as one of the processing steps. Systems for homography calculation usually observe homography as an inverse problem and provide an exact solution. However, the ...

2014

Real-time Implementation of Gaussian Image Blending in a Spherical Light Field Camera

Yusuf Leblebici, Alexandre Schmid, Vladan Popovic, Hossein Afshari

Panoptic is a custom spherical light field camera used as a polydioptric system where imagers are distributed over a spherical geometry, each having its own vision of the surrounding and a distinct focal plane. The spherical light field camera records ligh ...

Ieee2013

Image Blending in a High Frame Rate FPGA-based Multi-Camera System

Yusuf Leblebici, Alexandre Schmid, Vladan Popovic, Hossein Afshari, Kerem Seyid, Abdulkadir Akin, Ömer Cogal

Panoptic is a custom spherical light field camera used as a polydioptric system where imagers are distributed over a hemispherical surface, each having its own vision of the surroundings and a distinct focal plane. The spherical light field camera records ...

2013

Real-time FPGA implementation of linear blending vision reconstruction algorithm using a spherical light field camera

Yusuf Leblebici, Alexandre Schmid, Vladan Popovic, Hossein Afshari, Abdulkadir Akin

A custom spherical light-field camera used as a polydioptric system where imagers are distributed over a spherical geometry, each having its own vision of the surrounding and distinct focal plane. The spherical light-field camera is also an omnidirectional ...

2012

3D Reconstruction Of Wave-Propagated Point Sources From Boundary Measurements Using Joint Sparsity And Finite Rate Of Innovation

Dimitri Nestor Alice Van De Ville, Thierry Blu, Ivana Jovanovic, Zafer Dogan

Reconstruction of point sources from boundary measurements is a challenging problem in many applications. Recently, we proposed a new sensing and non-iterative reconstruction scheme for systems governed by the three-dimensional wave equation. The points so ...

IEEE Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2012

Design and Implementation of Multi-camera Systems Distributed over a Spherical Geometry

Yusuf Leblebici, Alexandre Schmid, Hossein Afshari, Kerem Seyid

The current trend in constructing high-end computing systems consists of parallelizing large numbers of processors. A similar trend is observed in digital imaging where multiple camera inputs are utilized to obtain multiple images of a scene and thus enhan ...

2012

Bio Simulation of Brain Ventricle Dilation in Normal Pressure Hydrocephalus

Kamal Shahim

Hydrocephalus is a brain disease wherein the ventricles dilate and compress the parenchyma towards the skull. It is primarily characterized by the disruption of the cerebrospinal fluid (CSF) flow within the ventricular system. Normal pressure hydrocephalus ...

EPFL2011

Diversity-Multiplexing Tradeoff for the MIMO Static Half-Duplex Relay

Olivier Lévêque

In this paper, we investigate the diversity-multiplexing tradeoff (DMT) of the multiple-antenna (MIMO) static half-duplex relay channel. A general expression is derived for the DMT upper bound, which can be achieved by a compress-and-forward protocol at th ...

Institute of Electrical and Electronics Engineers2010