Daytime visibility range monitoring through use of a roadside camera

Tra le innumerevoli opere digitalizzate disponibili sul sito della Biblioteca digitale francese Gallica merita una menzione speciale la collezione dei dizionari biografici: si tratta di opere enciclopediche di dimensioni talvolta monumentali, sicuramente ben note ai frequentatori delle sale di consultazione delle biblioteche. Elenco dei dizionari biografici digitalizzati attualmente disponibili su Gallica in formato immagine (riproduzione facsimilare): Biographie des 750 représentants à l'As..

Daytime visibility range monitoring through use of a roadside camera

Based on a road meteorology standard, we present a roadside camera-based system able to detect daytime fog and to estimate the visibility range. Two detection algorithms, both based on a daytime fog model, are presented along with a process to combine their outputs. Unlike previous methods, the system takes into account the 3-D scene structure and filters the moving objects from the region of interest through use of a background modelling approach and detects the cause of the visibility reduction. The study of the system accuracy with respect to the camera characteristics leads to a specification of the characteristics of the camera required for the system. Some results obtained using a reduced-scale prototyping of the system are presented. Finally, an outlook to future works is given

Un détecteur de points caractéristiques sur des images multispectrales. Extension vers un détecteur sub-pixellique

· Nous proposons dans cet article un détecteur de coins pour des images multispectrales. L'information multispectrale est réellement prise en compte puisque nous considérons ces images comme des champs de vecteurs, ce qui nous permet d'utiliser la géométrie différentielle. De bons résultats sont obtenus comme le montre une étude comparative entre ce détecteur et celui de Harris [HAR88]. Cependant, des délocalisations de coins apparaissent pour des images fortement lissées (ce qui est vrai pour une grande partie des détecteurs). C'est pourquoi nous avons implémenté une détection sub-pixellique à même de retrouver la position exacte du coin

Vers un système de détection et caractérisation par caméra de conditions météo critiques pour la sécurité routière

La présence d'une distance de visibilité réduite sur un réseau routier (épais brouillard, pluie forte, etc.) affecte la sécurité de celui-ci. Nous avons conçu un système de bord de voies qui vise à détecter des situations critiques telles que le brouillard dense ou les fortes chutes de pluie à l'aide d'une caméra vidéo. Les différents traitements d'image sont présentés, en particulier l'estimation de la distance de visibilité, la détection de brouillard, ainsi que la détection de pluie. En se fondant sur les principes sous-jacents de ces algorithmes, une caméra est ensuite spécifiée pour répondre aux besoins exprimés par la norme NF P 99-320 sur la météorologie routière. Des résultats expérimentaux sont présentés ainsi que des perspectives de validation à plus grande échelle.The presence ofa reduced visibility distance on a road network (thick fog, heavy rain, etc.) affects its safety. We designed a roadside system on which aims to detect critical situations such as dense fog or heavy rain with a simple CCTV camera. Different image processing are presented, particularly the estimation of visibility distance, the detection of fog, and the detection of rain. Based on the principles underlying these algorithms, a camera is specified to meet the needs expressed by the standard NF P 99-320 on highway meteorology. Experimental results are presented as well as prospective validation at a bigger scale

Backward Segmentation and Region Fitting for Geometrical Visibility Range Estimation

Abstract. We present a new application of computer vision: continuous measurement of the geometrical visibility range on inter-urban roads, solely based on a monocular image acquisition system. To tackle this problem, we propose first a road segmentation scheme based on a Parzenwindowing of a color feature space with an original update that allows us to cope with heterogeneously paved-roads, shadows and reflections, observed under various and changing lighting conditions. Second, we address the under-constrained problem of retrieving the depth information along the road based on the flat word assumption. This is performed by a new region-fitting iterative least squares algorithm, derived from half-quadratic theory, able to cope with vanishing-point estimation, and allowing us to estimate the geometrical visibility range.

Détection et caractérisation de points singuliers pour l' appariement et l' indexation d' images couleurs

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Local Zernike moment vector for content based queries in image database

International audienc

Meteorological Conditions Processing for Vision-based Traffic Monitoring

To monitor their networks, road operators equip them with cameras. Degraded meteorological conditions alter the transportation system operation by modifying the behavior of drivers and by reducing the operation range of the sensors. A vision-based traffic monitoring system is proposed to take fog and rain into account and react accordingly. A background modeling approach, based on a mixture of gaussians, is used to separate the foreground from the background. Since fog is steady weather, the background image is used to detect and quantify it and to restore the images. Since rain is a dynamic phenomenon, the foreground is used to detect it and rain streaks are removed from the images accordingly. The different detection algorithms are described and illustrated using actual images to show their potential benefits. The algorithms may be implemented in existing video-based traffic monitoring systems and allow the multiplication of applications running on roadside cameras