Search results for "rection"
showing 10 items of 965 documents
Atmospheric correction for land surface temperature using NOAA-11 AVHRR channels 4 and 5
1991
Abstract In this work, a theoretical model that permits relating the land surface temperature with the temperatures measured by thermal infrared sensors has been developed. The model has been derived by linearization of Planck's function and atmospheric trasmittance. In this way a split-window equation is obtained, which depends on atmospheric water vapor, viewing angle, and channel surface emissivities. Simulations of satellite measurements of land surface temperatures are made using the atmospheric transmittance-radiance model LOWTRAN-7 for NOAA-11 AVHRR Channels 4 and 5. From these simulations the accuracies of linearizations have been checked. The dependence of the split-window coeffici…
IV-Curves of tunnel junction arrays at lowered temperature by numerical simulation
1996
We have numerically investigated the effect of lowered T on the performance of the Coulomb blockade thermometer, which has been demostrated to yield primary thermometry in the high T limit where thermal excitations compete with the Coulomb blockade. The thermometer is formed by an array of tunnel junctions whose differentiated IV—curve is used to determine the temperature. The IV—curves were calculated by computer simulations and we have obtained corrections to the analytic high T behaviour due to the lowered temperature.
High-end colorimetric display characterization using an adaptive training set
2011
A new, accurate, and technology-independent display color-characterization model is introduced. It is based on polyharmonic spline interpolation and on an optimized adaptive training data set. The establishment of this model is fully automatic and requires only a few minutes, making it efficient in a practical situation. The experimental results are very good for both the forward and inverse models. Typically, the proposed model yields an average model prediction error of about 1 ∆Eab* unit or below for several displays. The maximum error is shown to be low as well. freedom given to the model considering the choice of a tar- get color space and of the kernel and smoothing factor for the int…
Parameters analysis influencing 3D measurement without contact by laser scanner to establish a local correction procedure
2007
International audience; The techniques of measuring without contact by laser scanning allows acquisition of a large number of points, at a very high rate speed ; nevertheless with less precision than the one obtained by classical techniques of measuring with contact. We present in this article the research and the experimental analysis of the influential parameters on the precision of the measure by laser sensor without contact. Firstly, a methodology of correction of the relative uncertainties in the conditions of the measuring laser is presented. Then, we apply it to a typical part and compare the results to those obtained by a classical procedure of measuring with a contact sensor. We fi…
Mélange de Gaussiennes Photométriques pour l'Asservissement Visuel Virtuel Direct d'une Caméra Omnidirectionnelle
2021
International audience; Cet article traite du suivi de pose direct basé modèle 3D. Nous considérons la transformation d’images omnidirectionnelles en Mélange de Gaussiennes Photométriquesn (MGP) comme primitives directes. Les contributions sont d’adapter l’optimisation de pose aux caméras omnidirectionnelles et de repenser les règles d’initialisation et d’optimisation du paramètre d’extension du MGP. Plusieurs évaluations montrent que cette approche augmente la taille du domaine de convergence. L’application à des images acquises avec un robot mobile placé dans un environnement urbain, représenté par un grand nuage de points 3D coloré, montre une robustesse significative aux grands mouvemen…
Estimation des Cartes du Temps de Collision (TTC) en Vision Para-catadioptrique
2013
National audience; Le temps de contact ou le temps de collision (TTC) est une information importante pour la navigation et l'évitement d'obtacles. Son estimation a largement été étudiée dans le cas des caméras perspectives. Par contre, très peu de travaux ont été effectués sur ce sujet pour les caméras catadioptriques, alors qu'elles sont très utiles, notamment, en navigation des robots mobiles. L'objectif de cet article, est de proposer un nouveau modèle d'estimation du TTC pour les caméras paracatadioptriques basé sur le flot optique, en adaptant celui développé pour les caméras perspectives. Le calcul du TTC en chaque pixel permet d'obtenir la carte des temps de collision. Nous avons val…
Presentations of constrained systems with unconstrained positions
2005
International audience; We give a polynomial-time construction of the set of sequences that satisfy a finite-memory constraint defined by a finite list of forbidden blocks, with a specified set of bit positions unconstrained. Such a construction can be used to build modulation/error-correction codes (ECC codes) like the ones defined by the Immink-Wijngaarden scheme in which certain bit positions are reserved for ECC parity. We give a lineartime construction of a finite-state presentation of a constrained system defined by a periodic list of forbidden blocks. These systems, called periodic-finite-type systems, were introduced by Moision and Siegel. Finally, we present a linear-time algorithm for con…
Multiple Structured Light-Based Depth Sensors for Human Motion Analysis: A Review
2012
Human motion analysis is an increasingly important active research domain with various applications in surveillance, human-machine interaction and human posture analysis. The recent developments in depth sensor technology, especially with the release of the Kinect device, have attracted significant attention to the question of how to take advantage of this technology in order to achieve accurate motion tracking and action detection in marker-less approaches. In this paper, we review the benefits and limitations deriving from the adoption of structured light-based depth sensors in human motion analysis applications. Surveying the relevant literature, we have identified in calibration, interf…
Mise en correspondance de lignes à partir de deux vues, estimation du mouvement et reconstruction pour les systèmes centraux
2011
The primary goal of this thesis is to develop generic motion and structure algorithms for images taken from constructed scenes by various types of central imaging systems including perspective, fish-eye and catadioptric systems. As-suming that the mapping between the image pixels and their 3D rays in space is known, instead of image planes, we work on image spheres (projection of the images on a unit sphere) which enable us to present points over the entire viewsphere suitable for presenting omnidirectional images. In the first part of this thesis, we develop a generic and simple line matching approach for images taken from constructed scenes under a short baseline motion as well as a fast …
Search for signatures of magnetically-induced alignment in the arrival directions measured by the Pierre Auger Observatory
2011
We present the results of an analysis of data recorded at the Pierre Auger Observatory in which we search for groups of directionally-aligned events (or ‘multiplets’) which exhibit a correlation between arrival direc- tion and the inverse of the energy. These signatures are expected from sets of events coming from the same source after having been deflected by intervening coherent magnetic fields. The observation of several events from the same source would open the possibility to accurately reconstruct the position of the source and also measure the integral of the component of the magnetic field orthogonal to the trajectory of the cos- mic rays. We describe the largest multiplets found an…