Depth Estimation Analysis of Orthogonally Divergent Fisheye Cameras with Distortion Removal

Stereo vision systems have become popular in computer vision applications, such as 3D reconstruction, object tracking, and autonomous navigation. However, traditional stereo vision systems that use rectilinear lenses may not be suitable for certain scenarios due to their limited field of view. This has led to the popularity of vision systems based on one or multiple fisheye cameras in different orientations, which can provide a field of view of 180x180 degrees or more. However, fisheye cameras introduce significant distortion at the edges that affects the accuracy of stereo matching and depth estimation. To overcome these limitations, this paper proposes a method for distortion-removal and depth estimation analysis for stereovision system using orthogonally divergent fisheye cameras (ODFC). The proposed method uses two virtual pinhole cameras (VPC), each VPC captures a small portion of the original view and presents it without any lens distortions, emulating the behavior of a pinhole camera. By carefully selecting the captured regions, it is possible to create a stereo pair using two VPCs. The performance of the proposed method is evaluated in both simulation using virtual environment and experiments using real cameras and their results compared to stereo cameras with parallel optical axes. The results demonstrate the effectiveness of the proposed method in terms of distortion removal and depth estimation accuracy

Un indicateur de fausses couleurs pour évaluer le traitement des images couleurs

National audienceDans le cas particulier du filtrage (lissage, rehaussement, etc.) d'images couleurs, les approches proposées peuvent faire apparaître dans l'image résultat des distorsions colorimétriques appelées alors "fausses couleurs", c'est-à-dire des couleurs indésirables non présentes dans l'image initiale. Parmi les nombreux indicateurs permettant d'évaluer les performances d'un filtrage, il n'existe pas actuellement de solution pour évaluer la quantité de fausses couleurs introduites dans l'image résultat. Le travail présenté propose un nouvel indicateur numérique, noté IFC pour Indicateur de Fausses Couleurs, capable de quantifier l'apparition de ces fausses couleurs. Cet indicateur peut être vu comme une mesure de performance du traitement au même titre que le rapport signal sur bruit. Les résultats proposés montrent que l'indicateur construit rend bien compte de la quantité de fausses couleurs introduites dans le résultat d'un filtrage

La Société algérienne de chimie

IntroductionLa chimie est une discipline-phare par ses applications industrielles. Elle est devenue une des composantes majeures des activités humaines. Selon le chimiste français Jean-Marie Lehn – prix Nobel de chimie en 1987 –, elle permet « à l’homme de connaître la matière et ses transformations, d’agir sur elle, de la modifier et d’en inventer de nouvelles manifestations ». Aussi joue t-elle un rôle central par son importance économique et son omniprésence dans notre vie quotidienne. Auj..

Introduction

Les circulations scientifiques internationales ont connu un développement important, en même temps que la communauté savante, depuis la Deuxième Guerre mondiale, et exponentiel au cours des dernières décennies. Pourtant, cette question, contrairement à celle des étudiants internationaux, n’a pas encore suscité beaucoup de travaux en sciences humaines et sociales. Ce mouvement de grande ampleur, qui n’épargne plus aucune région du globe, est volontiers observé et commenté, parfois à grand renf..

PDE Based Enhancement of Color Images in RGB Space

International audienceA novel method for color image enhancement is proposed as an extension of scalar diffusion-shock filter coupling model, where noisy and blurred images are denoised and sharpened. The proposed model is based on using single vectors of the gradient magnitude and the second derivatives as a technique to relate different color components of the image. This model can be viewed as a generalization of Bettahar-Stambouli filter to multi-valued images. The proposed algorithm is more efficient than the mentioned filter and some previous works on color image denoising and deblurring without creating false colors

The Analysis of Poverty Dynamics in Algeria: A Multidimensional Approach

The study of poverty is often oversimplified and, its manifestation, perceived as dichotomous. This conventional analysis is merely based upon the splitting of the population into two groups: poor and non-poor according to some hypothetical poverty line. This is called the one-dimensional approach of poverty. In addition there is no consensus regarding the poverty threshold, as Cerioli and Zani (1990) point out that a strict division of the population into poor and non-poor is unrealistic. To avoid this shortcoming, recent studies are increasingly using multidimensional analysis which will constitutes the first objective of this study that is concerned primarily with the application of this new methodology to the west part of Algeria with the emphasizing of two types of approaches: The Logit-Probit and the fuzzy set. The second objective is to comprehend the phenomenon of poverty within a systemic and dynamic approach. Our results show that the fuzzy set approach is more pertinent than the others in capturing different graded attributes of poverty. Therefore, the study reveals that income is not the sole indicator of well-being and should be supplemented by other attributes, mainly, housing, level of comfort and social capital. Moreover, the main finding highlights that rural areas are the most hit by deprivation and poverty. This analysis serves as a basis for a better targeting as far as policy options for poverty reduction are concerned

La géologie en Algérie (1880-1940)

Au début du XIXe siècle, comparée aux autres disciplines émergentes au moment de la conquête coloniale, la géologie occupe très tôt une place privilégiée et à part dans le dispositif académique qui se met en place progressivement en Algérie. Rappel historique de Yamina Bettahar.At the beginning of the XIXth century, geology became one of the major disciplines in Algeria, during the colonial conquest. A come back by Yamina Bettahar

Measurement of granular flow in a vertical column using pulse induction (PI)

Gravity flow of granular materials in vertical columns can generate pressure and density fluctuations which are difficult to quantify. Examination of prior research led us to propose a new measurement technique based on the principle of pulse induction (PI) for metal detection. An experimental device using 8 mm diameter spherical particles flowing through a polyvinylchloride (PVC) pipe of 75 mm diameter and 1000 mm height was developed to demonstrate the feasibility of PI. Ten PI coils were used to quantify tracer movement through the column with time. Average and instantaneous velocities were determined for five diameters of outlet orifices: 68.0, 62.5, 54.5, 44.0 and 36.5 mm. Flow rate was calculated and modelled. When compared to prior research, PI proved to be a reliable method for flow measurement in opaque ducts