Low-textured regions detection for improving stereoscopy algorithms

The main goal of stereoscopy algorithms is the calculation of the disparity map between two frames corresponding to the same scene, and captured simultaneously by two different cameras. The different position (disparity) where common scene points are projected in both camera sensors can be used to calculate the depth of the scene point. Many algorithms calculate the disparity of corresponding points in both frames relying on the existence of similar textured areas around the pixels to be analyzed. Unfortunately, real images present large areas with low texture, which hinder the calculation of the disparity map. In this paper we present a method that employs a set of local textures to build a classifier that is able to select reliable pixels where the disparity can be accurately calculated, improving the precision of the scene map obtained by the stereoscopic technique.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministry of Education and Science of Spain under contract TIN2010-16144 and Junta de Andalucía under contract TIC-1692

Multistep Explicit Stereo Camera Calibration Approach to Improve Euclidean Accuracy of Large-Scale 3D Reconstruction

The spatial accuracy of point clouds generated by stereo image-based 3D reconstruction algorithms is very sensitive to the intrinsic and extrinsic camera parameters determined during camera calibration. The existing camera calibration algorithms induce a significant amount of error due to poor estimation accuracies in camera parameters when they are used for large-scale scenes such as mapping civil infrastructure. This leads to higher uncertainties in the location of 3D points, and may result in the failure of the whole reconstruction process. This paper proposes a novel procedure to address this problem. It hypothesizes that a set of multiple calibrations created by videotaping a moving calibration pattern along a specific path can increase overall calibration accuracy. This is achieved by using conventional camera calibration algorithms to perform separate estimations for some predefined distance values. The result, which includes multiple sets of camera parameters, is then used in the Structure from Motion process to improve the Euclidean accuracy of the reconstruction. The proposed method has been tested on infrastructure scenes and experimental analyses indicate more than 25% improvement in the spatial accuracy of 3D points.This is the accepted manuscript. The final version is available from ASCE at http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.000045

An Improved Image Segmentation System: A Cooperative Multi-agent Strategy for 2D/3D Medical Images

In this paper, we present a solution-based cooperation approach for strengthening the image segmentation.This paper proposes a cooperative method relying on Multi-Agent System. The main contribution of this work is to highlight the importance of cooperation between the contour and region growing based on Multi-Agent System (MAS). Consequently, agents’ interactions form the main part of the whole process for image segmentation. Similar works were proposed to evaluate the effectiveness of the proposed solution. The main difference is that our Multi-Agent System can perform the segmentation process ensuring efficiency. Our results show that the performance indices in the system were higher. Furthermore, the integration of thecooperation paradigm allows to speed up the segmentation process. Besides, the tests reveal the robustness of our method by proving competitive results. Our proposal achieved an accuracy of 93,51%± 0,8, a sensitivity of 93,53%± 5,08 and a specificity rate of 92,64%± 4,01

Real Time UAV Altitude, Attitude and Motion Estimation form Hybrid Stereovision

International audienceKnowledge of altitude, attitude and motion is essential for an Unmanned Aerial Vehicle during crit- ical maneuvers such as landing and take-off. In this paper we present a hybrid stereoscopic rig composed of a fisheye and a perspective camera for vision-based navigation. In contrast to classical stereoscopic systems based on feature matching, we propose methods which avoid matching between hybrid views. A plane-sweeping approach is proposed for estimating altitude and de- tecting the ground plane. Rotation and translation are then estimated by decoupling: the fisheye camera con- tributes to evaluating attitude, while the perspective camera contributes to estimating the scale of the trans- lation. The motion can be estimated robustly at the scale, thanks to the knowledge of the altitude. We propose a robust, real-time, accurate, exclusively vision-based approach with an embedded C++ implementation. Although this approach removes the need for any non-visual sensors, it can also be coupled with an Inertial Measurement Unit

Large-scale industrial company alarm receiving centre modernization design

Particular functional blocks of Large-Scale Alarm receiving Centre modernization Design creates core contribution of this research paper. In the introductory chapter the valid legislation and the resulting requirements for the design, location, construction, technical equipment, operations and personnel are described. Moreover, the methodology of evaluation of the Alarm receiving Centre quality is proposed and applied to the particular company. The particular modernization related to selected areas such as communication or ergonomic layout of the workplace is then specified on the basis of the evaluation results. Moreover, the design of particular renovations is provided, including appropriately chosen technology and manufacturer, respectively provider

Cross-Spectral Face Recognition Between Near-Infrared and Visible Light Modalities.

In this thesis, improvement of face recognition performance with the use of images from the visible (VIS) and near-infrared (NIR) spectrum is attempted. Face recognition systems can be adversely affected by scenarios which encounter a significant amount of illumination variation across images of the same subject. Cross-spectral face recognition systems using images collected across the VIS and NIR spectrum can counter the ill-effects of illumination variation by standardising both sets of images. A novel preprocessing technique is proposed, which attempts the transformation of faces across both modalities to a feature space with enhanced correlation. Direct matching across the modalities is not possible due to the inherent spectral differences between NIR and VIS face images. Compared to a VIS light source, NIR radiation has a greater penetrative depth when incident on human skin. This fact, in addition to the greater number of scattering interactions within the skin by rays from the NIR spectrum can alter the morphology of the human face enough to disable a direct match with the corresponding VIS face. Several ways to bridge the gap between NIR-VIS faces have been proposed previously. Mostly of a data-driven approach, these techniques include standardised photometric normalisation techniques and subspace projections. A generative approach driven by a true physical model has not been investigated till now. In this thesis, it is proposed that a large proportion of the scattering interactions present in the NIR spectrum can be accounted for using a model for subsurface scattering. A novel subsurface scattering inversion (SSI) algorithm is developed that implements an inversion approach based on translucent surface rendering by the computer graphics field, whereby the reversal of the first order effects of subsurface scattering is attempted. The SSI algorithm is then evaluated against several preprocessing techniques, and using various permutations of feature extraction and subspace projection algorithms. The results of this evaluation show an improvement in cross spectral face recognition performance using SSI over existing Retinex-based approaches. The top performing combination of an existing photometric normalisation technique, Sequential Chain, is seen to be the best performing with a Rank 1 recognition rate of 92. 5%. In addition, the improvement in performance using non-linear projection models shows an element of non-linearity exists in the relationship between NIR and VIS

Recent Advances in Indoor Localization: A Survey on Theoretical Approaches and Applications

Nowadays, the availability of the location information becomes a key factor in today’s communications systems for allowing location based services. In outdoor scenarios, the Mobile Terminal (MT) position is obtained with high accuracy thanks to the Global Positioning System (GPS) or to the standalone cellular systems. However, the main problem of GPS or cellular systems resides in the indoor environment and in scenarios with deep shadowing effect where the satellite or cellular signals are broken. In this paper, we will present a review over different technologies and concepts used to improve indoor localization. Additionally, we will discuss different applications based on different localization approaches. Finally, comprehensive challenges in terms of accuracy, cost, complexity, security, scalability, etc. are presente

Detecção e seguimento de objectos em imagens termográficas: análise experimental de modelos de descrição

A instalação de sistemas de videovigilância, no interior ou exterior, em locais como aeroportos, centros comerciais, escritórios, edifícios estatais, bases militares ou casas privadas tem o intuito de auxiliar na tarefa de monitorização do local contra eventuais intrusos. Com estes sistemas é possível realizar a detecção e o seguimento das pessoas que se encontram no ambiente local, tornando a monitorização mais eficiente. Neste contexto, as imagens típicas (imagem natural e imagem infravermelha) são utilizadas para extrair informação dos objectos detectados e que irão ser seguidos. Contudo, as imagens convencionais são afectadas por condições ambientais adversas como o nível de luminosidade existente no local (luzes muito fortes ou escuridão total), a presença de chuva, de nevoeiro ou de fumo que dificultam a tarefa de monitorização das pessoas. Deste modo, tornou‐se necessário realizar estudos e apresentar soluções que aumentem a eficácia dos sistemas de videovigilância quando sujeitos a condições ambientais adversas, ou seja, em ambientes não controlados, sendo uma das soluções a utilização de imagens termográficas nos sistemas de videovigilância. Neste documento são apresentadas algumas das características das câmaras e imagens termográficas, assim como uma caracterização de cenários de vigilância. Em seguida, são apresentados resultados provenientes de um algoritmo que permite realizar a segmentação de pessoas utilizando imagens termográficas. O maior foco desta dissertação foi na análise dos modelos de descrição (Histograma de Cor, HOG, SIFT, SURF) para determinar o desempenho dos modelos em três casos: distinguir entre uma pessoa e um carro; distinguir entre duas pessoas distintas e determinar que é a mesma pessoa ao longo de uma sequência. De uma forma sucinta pretendeu‐se, com este estudo, contribuir para uma melhoria dos algoritmos de detecção e seguimento de objectos em sequências de vídeo de imagens termográficas. No final, através de uma análise dos resultados provenientes dos modelos de descrição, serão retiradas conclusões que servirão de indicação sobre qual o modelo que melhor permite discriminar entre objectos nas imagens termográficas.This report presents the work accomplished for the Thesis/Dissertation module of the Masters Degree in Electrical and Computer Engineering – within the Telecommunications area of expertise. Currently, automatic monitoring in video surveillance systems in environments such as airports, shopping malls, government buildings, office buildings, and private home is done through the use of detection and object tracking techniques. Natural images and near‐infrared images are mainly accessed through video surveillance in order to extract information on the object detected and subsequently being tracking. However, due to variations in environmental conditions within surveillance scenarios, severe drawbacks are exhibited when used for night‐time surveillance and/or in scenes with harsh environmental conditions such as strong light, total darkness, smoke, rain and fog. Therefore, it became more and more important to present a solution that could overcome those disadvantages. A possible solution is to make use of thermal images. This dissertation aims to analyze descriptors models such as Color Histograms, HOG, SIFT and SURF, to conclude if they are able or not to be used to distinguish between an object representing a non‐person and a person and between two different persons due to their similarity. In addition, a study of a set of scenarios with harsh environmental conditions and also results of a segmentation algorithm are presented. In short, the entire study intends to contribute for a better performance of video object detection and tracking algorithms. At the end, through the analysis of the set of results from the descriptors models, conclusions are drawn in order to indicate which of the models can better distinguish the detected objects in thermal images

Teolliset älykamerat ja tuotantolinjan laaduntarkastussovelluksen rakentaminen

The technologies for continuous monitoring, diagnostics, prognostics, and control of assets have been developing tremendously in recent years. The new technologies provide tools to achieve greater predictability of plant behaviour and visibility, reduced safety risks, enhanced security and cost efficiency. eSonia project is researching a possibility to create an asset-aware and self recovery plant. In this thesis is implemented quality inspection part of eSonia project. The implementation includes choosing the camera and the components, building the inspection and the user interfaces, and also creating robust communication between the camera and the plant by using mixture of old industrial standards (like Modbus) and new technologies (like web services). The roadmap for building a machine vision application was tailored to suit smart cameras, and all the steps for building the inspection has been presented in detail. The implementation was done by using National Instrument’s NI1774C smart camera, and National Instruments Vision Builder AI software, and the web service was build on Inico’s remote terminal unit S1000. The hardware and software composition proved to be suitable to perform all the tasks, and to be well suited to the asset-aware factory environment. In this thesis is also presented the state of arts of smart cameras, for off-the-shelf solutions as well as for research projects. The market for smart cameras is increasing rapidly, and the market situation is presented together with the direction for future technological development