Design of a training tool for improving the use of hand-held detectors in humanitarian demining

Purpose - The purpose of this paper is to introduce the design of a training tool intended to improve deminers' technique during close-in detection tasks. Design/methodology/approach - Following an introduction that highlights the impact of mines and improvised explosive devices (IEDs), and the importance of training for enhancing the safety and the efficiency of the deminers, this paper considers the utilization of a sensory tracking system to study the skill of the hand-held detector expert operators. With the compiled information, some critical performance variables can be extracted, assessed, and quantified, so that they can be used afterwards as reference values for the training task. In a second stage, the sensory tracking system is used for analysing the trainee skills. The experimentation phase aims to test the effectiveness of the elements that compose the sensory system to track the hand-held detector during the training sessions. Findings - The proposed training tool will be able to evaluate the deminers' efficiency during the scanning tasks and will provide important information for improving their competences. Originality/value - This paper highlights the need of introducing emerging technologies for enhancing the current training techniques for deminers and proposes a sensory tracking system that can be successfully utilised for evaluating trainees' performance with hand-held detectors. © Emerald Group Publishing Limited.The authors acknowledge funding from the European Community's Seventh Framework Programme (FP7/2007‐2013 TIRAMISU) under Grant Agreement No. 284747 and partial funding under Robocity2030 S‐0505/DPI‐0176 and FORTUNA A1/039883/11 (Agencia Española de Cooperación Internacional para el Desarrollo – AECID). Dr Roemi Fernández acknowledges support from CSIC under grant JAE‐DOC. Dr Héctor Montes acknowledges support from Universidad Tecnológica de Panamá and from CSIC under grant JAE‐DOC.Peer Reviewe

Design of a training tool for improving the use of hand-held detectors in humanitarian demining

Purpose – The purpose of this paper is to introduce the design of a training tool intended to improve deminers' technique during close-in detection tasks. Design/methodology/approach – Following an introduction that highlights the impact of mines and improvised explosive devices (IEDs), and the importance of training for enhancing the safety and the efficiency of the deminers, this paper considers the utilization of a sensory tracking system to study the skill of the hand-held detector expert operators. With the compiled information, some critical performance variables can be extracted, assessed, and quantified, so that they can be used afterwards as reference values for the training task. In a second stage, the sensory tracking system is used for analysing the trainee skills. The experimentation phase aims to test the effectiveness of the elements that compose the sensory system to track the hand-held detector during the training sessions. Findings – The proposed training tool will be able to evaluate the deminers' efficiency during the scanning tasks and will provide important information for improving their competences. Originality/value – This paper highlights the need of introducing emerging technologies for enhancing the current training techniques for deminers and proposes a sensory tracking system that can be successfully utilised for evaluating trainees' performance with hand-held detectors

Modeling the environment with egocentric vision systems

Cada vez más sistemas autónomos, ya sean robots o sistemas de asistencia, están presentes en nuestro día a día. Este tipo de sistemas interactúan y se relacionan con su entorno y para ello necesitan un modelo de dicho entorno. En función de las tareas que deben realizar, la información o el detalle necesario del modelo varía. Desde detallados modelos 3D para sistemas de navegación autónomos, a modelos semánticos que incluyen información importante para el usuario como el tipo de área o qué objetos están presentes. La creación de estos modelos se realiza a través de las lecturas de los distintos sensores disponibles en el sistema. Actualmente, gracias a su pequeño tamaño, bajo precio y la gran información que son capaces de capturar, las cámaras son sensores incluidos en todos los sistemas autónomos. El objetivo de esta tesis es el desarrollar y estudiar nuevos métodos para la creación de modelos del entorno a distintos niveles semánticos y con distintos niveles de precisión. Dos puntos importantes caracterizan el trabajo desarrollado en esta tesis: - El uso de cámaras con punto de vista egocéntrico o en primera persona ya sea en un robot o en un sistema portado por el usuario (wearable). En este tipo de sistemas, las cámaras son solidarias al sistema móvil sobre el que van montadas. En los últimos años han aparecido muchos sistemas de visión wearables, utilizados para multitud de aplicaciones, desde ocio hasta asistencia de personas. - El uso de sistemas de visión omnidireccional, que se distinguen por su gran campo de visión, incluyendo mucha más información en cada imagen que las cámara convencionales. Sin embargo plantean nuevas dificultades debido a distorsiones y modelos de proyección más complejos. Esta tesis estudia distintos tipos de modelos del entorno: - Modelos métricos: el objetivo de estos modelos es crear representaciones detalladas del entorno en las que localizar con precisión el sistema autónomo. Ésta tesis se centra en la adaptación de estos modelos al uso de visión omnidireccional, lo que permite capturar más información en cada imagen y mejorar los resultados en la localización. - Modelos topológicos: estos modelos estructuran el entorno en nodos conectados por arcos. Esta representación tiene menos precisión que la métrica, sin embargo, presenta un nivel de abstracción mayor y puede modelar el entorno con más riqueza. %, por ejemplo incluyendo el tipo de área de cada nodo, la localización de objetos importantes o el tipo de conexión entre los distintos nodos. Esta tesis se centra en la creación de modelos topológicos con información adicional sobre el tipo de área de cada nodo y conexión (pasillo, habitación, puertas, escaleras...). - Modelos semánticos: este trabajo también contribuye en la creación de nuevos modelos semánticos, más enfocados a la creación de modelos para aplicaciones en las que el sistema interactúa o asiste a una persona. Este tipo de modelos representan el entorno a través de conceptos cercanos a los usados por las personas. En particular, esta tesis desarrolla técnicas para obtener y propagar información semántica del entorno en secuencias de imágen

Enhancing 3D Visual Odometry with Single-Camera Stereo Omnidirectional Systems

We explore low-cost solutions for efficiently improving the 3D pose estimation problem of a single camera moving in an unfamiliar environment. The visual odometry (VO) task -- as it is called when using computer vision to estimate egomotion -- is of particular interest to mobile robots as well as humans with visual impairments. The payload capacity of small robots like micro-aerial vehicles (drones) requires the use of portable perception equipment, which is constrained by size, weight, energy consumption, and processing power. Using a single camera as the passive sensor for the VO task satisfies these requirements, and it motivates the proposed solutions presented in this thesis. To deliver the portability goal with a single off-the-shelf camera, we have taken two approaches: The first one, and the most extensively studied here, revolves around an unorthodox camera-mirrors configuration (catadioptrics) achieving a stereo omnidirectional system (SOS). The second approach relies on expanding the visual features from the scene into higher dimensionalities to track the pose of a conventional camera in a photogrammetric fashion. The first goal has many interdependent challenges, which we address as part of this thesis: SOS design, projection model, adequate calibration procedure, and application to VO. We show several practical advantages for the single-camera SOS due to its complete 360-degree stereo views, that other conventional 3D sensors lack due to their limited field of view. Since our omnidirectional stereo (omnistereo) views are captured by a single camera, a truly instantaneous pair of panoramic images is possible for 3D perception tasks. Finally, we address the VO problem as a direct multichannel tracking approach, which increases the pose estimation accuracy of the baseline method (i.e., using only grayscale or color information) under the photometric error minimization as the heart of the “direct” tracking algorithm. Currently, this solution has been tested on standard monocular cameras, but it could also be applied to an SOS. We believe the challenges that we attempted to solve have not been considered previously with the level of detail needed for successfully performing VO with a single camera as the ultimate goal in both real-life and simulated scenes

Combining omnidirectional vision with polarization vision for robot navigation

La polarisation est le phénomène qui décrit les orientations des oscillations des ondes lumineuses qui sont limitées en direction. La lumière polarisée est largement utilisée dans le règne animal,à partir de la recherche de nourriture, la défense et la communication et la navigation. Le chapitre (1) aborde brièvement certains aspects importants de la polarisation et explique notre problématique de recherche. Nous visons à utiliser un capteur polarimétrique-catadioptrique car il existe de nombreuses applications qui peuvent bénéficier d'une telle combinaison en vision par ordinateur et en robotique, en particulier pour l'estimation d'attitude et les applications de navigation. Le chapitre (2) couvre essentiellement l'état de l'art de l'estimation d'attitude basée sur la vision.Quand la lumière non-polarisée du soleil pénètre dans l'atmosphère, l'air entraine une diffusion de Rayleigh, et la lumière devient partiellement linéairement polarisée. Le chapitre (3) présente les motifs de polarisation de la lumière naturelle et couvre l'état de l'art des méthodes d'acquisition des motifs de polarisation de la lumière naturelle utilisant des capteurs omnidirectionnels (par exemple fisheye et capteurs catadioptriques). Nous expliquons également les caractéristiques de polarisation de la lumière naturelle et donnons une nouvelle dérivation théorique de son angle de polarisation.Notre objectif est d'obtenir une vue omnidirectionnelle à 360 associée aux caractéristiques de polarisation. Pour ce faire, ce travail est basé sur des capteurs catadioptriques qui sont composées de surfaces réfléchissantes et de lentilles. Généralement, la surface réfléchissante est métallique et donc l'état de polarisation de la lumière incidente, qui est le plus souvent partiellement linéairement polarisée, est modifiée pour être polarisée elliptiquement après réflexion. A partir de la mesure de l'état de polarisation de la lumière réfléchie, nous voulons obtenir l'état de polarisation incident. Le chapitre (4) propose une nouvelle méthode pour mesurer les paramètres de polarisation de la lumière en utilisant un capteur catadioptrique. La possibilité de mesurer le vecteur de Stokes du rayon incident est démontré à partir de trois composants du vecteur de Stokes du rayon réfléchi sur les quatre existants.Lorsque les motifs de polarisation incidents sont disponibles, les angles zénithal et azimutal du soleil peuvent être directement estimés à l'aide de ces modèles. Le chapitre (5) traite de l'orientation et de la navigation de robot basées sur la polarisation et différents algorithmes sont proposés pour estimer ces angles dans ce chapitre. A notre connaissance, l'angle zénithal du soleil est pour la première fois estimé dans ce travail à partir des schémas de polarisation incidents. Nous proposons également d'estimer l'orientation d'un véhicule à partir de ces motifs de polarisation.Enfin, le travail est conclu et les possibles perspectives de recherche sont discutées dans le chapitre (6). D'autres exemples de schémas de polarisation de la lumière naturelle, leur calibrage et des applications sont proposées en annexe (B).Notre travail pourrait ouvrir un accès au monde de la vision polarimétrique omnidirectionnelle en plus des approches conventionnelles. Cela inclut l'orientation bio-inspirée des robots, des applications de navigation, ou bien la localisation en plein air pour laquelle les motifs de polarisation de la lumière naturelle associés à l'orientation du soleil à une heure précise peuvent aboutir à la localisation géographique d'un véhiculePolarization is the phenomenon that describes the oscillations orientations of the light waves which are restricted in direction. Polarized light has multiple uses in the animal kingdom ranging from foraging, defense and communication to orientation and navigation. Chapter (1) briefly covers some important aspects of polarization and explains our research problem. We are aiming to use a polarimetric-catadioptric sensor since there are many applications which can benefit from such combination in computer vision and robotics specially robot orientation (attitude estimation) and navigation applications. Chapter (2) mainly covers the state of art of visual based attitude estimation.As the unpolarized sunlight enters the Earth s atmosphere, it is Rayleigh-scattered by air, and it becomes partially linearly polarized. This skylight polarization provides a signi cant clue to understanding the environment. Its state conveys the information for obtaining the sun orientation. Robot navigation, sensor planning, and many other applications may bene t from using this navigation clue. Chapter (3) covers the state of art in capturing the skylight polarization patterns using omnidirectional sensors (e.g fisheye and catadioptric sensors). It also explains the skylight polarization characteristics and gives a new theoretical derivation of the skylight angle of polarization pattern. Our aim is to obtain an omnidirectional 360 view combined with polarization characteristics. Hence, this work is based on catadioptric sensors which are composed of reflective surfaces and lenses. Usually the reflective surface is metallic and hence the incident skylight polarization state, which is mostly partially linearly polarized, is changed to be elliptically polarized after reflection. Given the measured reflected polarization state, we want to obtain the incident polarization state. Chapter (4) proposes a method to measure the light polarization parameters using a catadioptric sensor. The possibility to measure the incident Stokes is proved given three Stokes out of the four reflected Stokes. Once the incident polarization patterns are available, the solar angles can be directly estimated using these patterns. Chapter (5) discusses polarization based robot orientation and navigation and proposes new algorithms to estimate these solar angles where, to the best of our knowledge, the sun zenith angle is firstly estimated in this work given these incident polarization patterns. We also propose to estimate any vehicle orientation given these polarization patterns. Finally the work is concluded and possible future research directions are discussed in chapter (6). More examples of skylight polarization patterns, their calibration, and the proposed applications are given in appendix (B). Our work may pave the way to move from the conventional polarization vision world to the omnidirectional one. It enables bio-inspired robot orientation and navigation applications and possible outdoor localization based on the skylight polarization patterns where given the solar angles at a certain date and instant of time may infer the current vehicle geographical location.DIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Vision Sensors and Edge Detection

Vision Sensors and Edge Detection book reflects a selection of recent developments within the area of vision sensors and edge detection. There are two sections in this book. The first section presents vision sensors with applications to panoramic vision sensors, wireless vision sensors, and automated vision sensor inspection, and the second one shows image processing techniques, such as, image measurements, image transformations, filtering, and parallel computing

Omnidirectional Light Field Analysis and Reconstruction

Digital photography exists since 1975, when Steven Sasson attempted to build the first digital camera. Since then the concept of digital camera did not evolve much: an optical lens concentrates light rays onto a focal plane where a planar photosensitive array transforms the light intensity into an electric signal. During the last decade a new way of conceiving digital photography emerged: a photography is the acquisition of the entire light ray field in a confined region of space. The main implication of this new concept is that a digital camera does not acquire a 2-D signal anymore, but a 5-D signal in general. Acquiring an image becomes more demanding in terms of memory and processing power; at the same time, it offers the users a new set of possibilities, like choosing dynamically the focal plane and the depth of field of the final digital photo. In this thesis we develop a complete mathematical framework to acquire and then reconstruct the omnidirectional light field around an observer. We also propose the design of a digital light field camera system, which is composed by several pinhole cameras distributed around a sphere. The choice is not casual, as we take inspiration from something already seen in nature: the compound eyes of common terrestrial and flying insects like the house fly. In the first part of the thesis we analyze the optimal sampling conditions that permit an efficient discrete representation of the continuous light field. In other words, we will give an answer to the question: how many cameras and what resolution are needed to have a good representation of the 4-D light field? Since we are dealing with an omnidirectional light field we use a spherical parametrization. The results of our analysis is that we need an irregular (i.e., not rectangular) sampling scheme to represent efficiently the light field. Then, to store the samples we use a graph structure, where each node represents a light ray and the edges encode the topology of the light field. When compared to other existing approaches our scheme has the favorable property of having a number of samples that scales smoothly for a given output resolution. The next step after the acquisition of the light field is to reconstruct a digital picture, which can be seen as a 2-D slice of the 4-D acquired light field. We interpret the reconstruction as a regularized inverse problem defined on the light field graph and obtain a solution based on a diffusion process. The proposed scheme has three main advantages when compared to the classic linear interpolation: it is robust to noise, it is computationally efficient and can be implemented in a distributed fashion. In the second part of the thesis we investigate the problem of extracting geometric information about the scene in the form of a depth map. We show that the depth information is encoded inside the light field derivatives and set up a TV-regularized inverse problem, which efficiently calculates a dense depth map of the scene while respecting the discontinuities at the boundaries of objects. The extracted depth map is used to remove visual and geometrical artifacts from the reconstruction when the light field is under-sampled. In other words, it can be used to help the reconstruction process in challenging situations. Furthermore, when the light field camera is moving temporally, we show how the depth map can be used to estimate the motion parameters between two consecutive acquisitions with a simple and effective algorithm, which does not require the computation nor the matching of features and performs only simple arithmetic operations directly in the pixel space. In the last part of the thesis, we introduce a novel omnidirectional light field camera that we call Panoptic. We obtain it by layering miniature CMOS imagers onto an hemispherical surface, which are then connected to a network of FPGAs. We show that the proposed mathematical framework is well suited to be embedded in hardware by demonstrating a real time reconstruction of an omnidirectional video stream at 25 frames per second

Applications de la vision omnidirectionnelle à la perception de scènes pour des systèmes mobiles

Ce mémoire présente une synthèse des travaux que j’ai menés à l’ESIGELEC au sein de son institut de recherche l’IRSEEM. Mes activités de recherche ont porté dans un premier temps sur la conception et l’évaluation de dispositifs de mesure de la dynamique de la marche de personnes atteintes de pathologies de la hanche, dans le cadre de ma thèse effectuée à l’université de Rouen en lien le Centre Hospitalo-Universitaire de Rouen. En 2003, j’ai rejoint les équipes de recherche qui se constituaient avec la mise sur pieds de l’IRSEEM, Institut de Recherche en Systèmes Electroniques Embarqués, créé en 2001. Dans ce laboratoire, j’ai structuré et développé une activité de recherche dans le domaine de la vision par ordinateur appliquée au véhicule intelligent et à la robotique mobile autonome. Dans un premier temps, j’ai concentré mes travaux à l’étude de systèmes de vision omnidirectionnelle tels que les capteurs catadioptriques centraux et leur utilisation pour des applications mobiles embarquées ou débarquées : modélisation et calibrage, reconstruction tridimensionnelle de scènes par stéréovision et déplacement du capteur. Dans un second temps, je me suis intéressé à la conception et la mise en œuvre de systèmes de vision à projection non centrale (capteurs catadioptriques à miroirs composés, caméra plénoptique). Ces travaux ont été effectués au travers en collaboration avec le MIS de l‘Université Picardie Jules Verne et l’ISIR de l’Université Pierre et Marie Curie. Enfin, dans le cadre d’un programme de recherche en collaboration avec l’Université du Kent, j’ai consacré une partie de mes travaux à l’adaptation de méthodes de traitement d’images et de classification pour la détection de visages sur images omnidirectionnelles (adaptation du détecteur de Viola et Jones) et à la reconnaissance biométrique d’une personne par analyse de sa marche. Aujourd’hui, mon activité s’inscrit dans le prolongement du renforcement des projets de l’IRSEEM dans le domaine de la robotique mobile et du véhicule autonome : mise en place d’un plateau de mesures pour la navigation autonome, coordination de projets de recherche en prise avec les besoins industriels. Mes perspectives de recherche ont pour objet l’étude de nouvelles solutions pour la perception du mouvement et la localisation en environnement extérieur et sur les méthodes et moyens nécessaires pour objectiver la performance et la robustesse de ces solutions sur des scénarios réalistes