Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2014. / Made available in DSpace on 2014-08-06T18:11:32Z (GMT). No. of bitstreams: 1 326967.pdf: 12320050 bytes, checksum: af4147753d0f51ce7a4d52613b9b1fa1 (MD5) Previous issue date: 2014 / Visão estereoscópica é o processo de estimação da informação de profundidade de uma cena, ou de um objeto em particular, por meio da análise de duas imagens capturadas em diferentes pontos de vista, usando um modelo apropriado de câmera. As câmeras permitem uma rica representação da cena quando comparadas a outros sistemas, como laser, radar e sonar, sendo cada vez mais usadas em aplicações de robótica móvel e do setor automotivo, tais como navegação autônoma e detecção de objetos e obstáculos. Sistemas de visão estereoscópica são também utilizados em aplicações de metrologia e de sensoriamento remoto, e são caracterizados por três etapas principais: calibração, registro de imagens e reconstrução. A reconstrução da informação de profundidade em sistemas de visão estereoscópica é influenciada pela distorção das lentes. Neste trabalho, estuda-se o comportamento do erro de reconstrução em função do aumento da ordem do modelo de correção da distorção e propõe-se um novo método de correção da distorção de lentes, baseado na estimação de um conjunto de coeficientes de correção da distorção para cada região da imagem. A avaliação do sistema, feita por simulação com imagens sintéticas, indica que a aplicação do método proposto possibilita obter erro de reconstrução menor que o obtido pela aplicação do método convencional.<br> / Abstract : Stereo Vision is the process of recovery of three-dimensional information of a scene, or an object of scene, from the analysis of two bi-dimensional images by using an appropriate camera model. The cameras allow for a rich representation of the scene when compared to others types of sensors, such as laser and sonar, being used more and more in applications for mobile robotics and assistance driving, such as object and obstacle detection and localization. Stereo Vision is also used in remote sensing and Metrology, and is composed of three main steps: camera calibration, pixel correspondence and 3-D reconstruction. Lens distortion is one of the main factors that limits the accuracy of stereo vision system reconstruction. We propose a new method for correction of the lens distortion by applying compensation to each region of an image. Our method splits the image into smaller regions and compensates for each region for a fixed lenses model order. When compared to the conventional method, which models the entire image with only one model, our approach provides better compensation and reduce the depth error as show in the experiments with synthetic data.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-13T13:11:33Z No. of bitstreams: 1 DissCAG.pdf: 1588922 bytes, checksum: a5934cedb789c0456c3051fcde155acb (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T20:29:41Z (GMT) No. of bitstreams: 1 DissCAG.pdf: 1588922 bytes, checksum: a5934cedb789c0456c3051fcde155acb (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T20:29:51Z (GMT) No. of bitstreams: 1 DissCAG.pdf: 1588922 bytes, checksum: a5934cedb789c0456c3051fcde155acb (MD5) / Made available in DSpace on 2016-09-13T20:30:12Z (GMT). No. of bitstreams: 1 DissCAG.pdf: 1588922 bytes, checksum: a5934cedb789c0456c3051fcde155acb (MD5) Previous issue date: 2015-03-18 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The nest predation is an event that adversely affects the reproductive success of birds. One of the main theories explaining their population decline is the "Theory mesopredator release", especially in fragmented areas, where the chain of top predators are the first to go extinct, causing an increase in mesopredators in place, leading to an growth in nest predation and reduction of the bird population. In this context, estimate the nest predation, through the use of artificial nests is of paramount importance both in preserved areas, as fragmented, present in the vicinity of protected areas in order to know which are the natural predators of nests, estimates predation intensity, quickly, in different landscapes present in the Atlantic Forest biome. Thus, the artificial nests was sampled through the use of nests (artificial), each containing two nest eggs of domestic fowl Quail (Coturnix cotunix), and camera traps. In all study areas the cameras and the nests were placed together in the field (both at the top, as on the ground), so that predation records were provided by recording 30-second videos filmed by the cameras. In Carlos Botelho State Park (CBSP) gave a sampling effort 2100 cameras/night. It’s surrounding area analyzed, corresponding to the Agroforestry System (AS) provided 7200 cameras/hours sampling. As for the territorial portion of the Capão Bonito National Forest (NF) and its surroundings were sampled together, making an effort 1155 cameras/night. Several species of birds (10), reptiles (1) and mammals (7) were recorded preying on the eggs, accounting for an overall predation rate, for all fields of study, 42.6%. The CBSP obtained a 28.6% predation rate, corresponding to the rates in other areas as well preserved. Not so for NF he presented such a high rate (45.8%) as found in disturbed environments analyzed, AS and surrounding National Forest (100% and 65.5%, respectively). Among birds, the main predators were “Arapaçu de bico preto” (Dendrocolaptes platyrostris), “Falcão Relógio” (Micrastur semitorquatus) and “Macuco” (Tinamus solitarius), in Carlos Botelho State Park. In NF, the “Gralha-decrista- negra” (Cyanocorax chrysops), stood out as the main predator bird, and the “Gralha-Azul” (Cyanocorax caeruleus) for the AS. Among mammals, the CBSP the “Cuíca-de-quatro-olhos” (Philander frenatus) and the “Irara” (Eira barbara) were the most prominent. In NF, the "Javaporco" (Sus sp) became the dominant predator. In AS, the “Gambá-de-orelha-preta” (Didelphis aurita) was the only mammal predator. And for the group of reptiles, only the “Teiú” (Tupinambis merinae) did prey the nest in Carlos Botelho. In addition, depredations on the ground were the most abundant in all areas of study, corresponding 65% of predation compared to 35% of depredations on top, and during the daytime, corresponding to 77%. Thus, we can conclude that nests on the ground, depredations during the day, for bird species, corresponds to the profile of nest predators in the Atlantic Forest in the State of São Paulo. Nevertheless, the NF proved to be very close in terms of species composition and predation rate your anthropic environment. And the alternative of sustainable production, AS, resembled much of the damage also caused by conventional production of agricultural products (NF surroundings), in this case, the fauna of birds present in the Atlantic Forest. / A predação de ninhos é um evento que afeta negativamente o sucesso reprodutivo das aves. Uma das principais teorias que explicam seu declínio populacional é a “Teoria de Liberação de Mesopredadores”, principalmente em áreas fragmentadas, onde os predadores de topo de cadeia são os primeiros a se extinguirem, causando um aumento dos mesopredadores no local, levando a um crescimento na predação de ninhos e na redução da população de aves. Neste contexto, estimar a predação de ninhos, através do uso de ninhos artificiais é de suma importância, tanto em áreas preservadas, como fragmentadas presentes no entorno de Unidades de Conservação, a fim de conhecer quais são os predadores naturais de ninhos, as estimativas de intensidade de predação, de maneira rápida, nas diferentes paisagens presentes no Bioma Mata Atlântica. Desse modo, a predação de ninhos artificiais foi amostrada por meio do uso de ninhos (artificiais), contendo cada ninho dois ovos da ave doméstica Codorna (Coturnix cotunix), e armadilhas fotográficas (Câmeras traps). Em todas as áreas de estudo as câmeras e os ninhos foram dispostos juntos no campo (tanto no alto, como no chão), a fim de que registros de predações fossem proporcionados pela gravação de vídeos de 30 segundos filmados pelas câmeras. No Parque Estadual Carlos Botelho (PECB) obteve-se um esforço amostral de 2100 câmeras/noite. Sua área de entorno analisada, correspondendo ao Sistema Agroflorestal (SAF) proporcionou 7200 horas/câmera de amostragem. Já para a porção territorial da Floresta Nacional (FLONA) de Capão Bonito e seu entorno foram amostradas juntas, perfazendo um esforço de 1155 câmeras/noite. Diversas espécies de aves (10), répteis (1) e mamíferos (7) foram registradas predando os ovos, contabilizando uma taxa de predação geral, para todas as áreas de estudo, de 42,6%. O PECB obteve uma taxa de predação de 28,6%, correspondendo ás taxas em outras áreas também preservadas. O mesmo não aconteceu para a FLONA em que apresentou uma taxa tão alta (45,8%) quanto a encontrada nos ambientes perturbados analisados, SAF e entorno FLONA (100% e 65,5%, respectivamente). Entre as aves, os principais predadores foram: Arapaçu de bico preto (Dendrocolaptes platyrostris), Falcão Relógio (Micrastur semitorquatus) e Macuco (Tinamus solitarius), no Parque Estadual Carlos Botelho. Na FLONA, a Gralha-decrista- negra (Cyanocorax chrysops), destacou-se como principal ave predadora, assim como a Gralha azul (Cyanocorax caeruleus) para o SAF. Entre os mamíferos, no PECB a Cuíca de quatro olhos (Philander frenatus) e a Irara (Eira barbara) foram os de maior destaque. Na FLONA, o “Javaporco” (Sus sp) tornou-se o predador dominante. No SAF, o Gambá de orelha preta (Didelphis aurita), foi o único predador mamífero. E para o grupo dos répteis, somente o Teiú (Tupinambis merinae) predou o ninho, em Carlos Botelho. Além disso, predações no chão foram as mais abundantes em todas as áreas de estudo, correspondendo 65% das predações em relação a 35% de predações no alto, e durante o período diurno, correspondendo a 77%. Desse modo, pode-se concluir que ninhos no chão, predações durante o dia, por espécies de aves, corresponde ao perfil de predadores de ninhos na Mata Atlântica no Estado de São Paulo. Não obstante, a FLONA mostrou-se muito próxima a nível de composição de espécies e taxa de predação a seu entorno antropizado. E, a alternativa de produção sustentável, o SAF, se assemelhou muito aos prejuízos também causados pela produção convencional de produtos agrícolas (entorno FLONA), no caso, à fauna de aves presentes na Mata Atlântica.

Thesis (Master Diploma (Electrical Engineering))-- Cape Technikon, Cape Town, 1988 / This thesis describes the control system developed to improve the efficiency of star acquisition on a ground-based optical telescope. "Star Acquisition" refers to the process of identifying the star of interest in a field of stars and centering it on the optical axis of the telescope , as well as setting an autoguider detector on a suitable star so the autoguider can improve the tracking performance of the telescope. Efficiency is improved by making all functions remote controlled , so the astronomer does not have to move between the control room and the telescope to operate the instrument.

Orientador: Antonio Maria Tommaselli / Resumo: Com o aumento do uso das câmaras digitais não métricas em aplicações fotogramétricas, tem crescido a necessidade pela calibração destas câmaras e pela freqüência de realização desta. Com o objetivo de tornar mais simples a utilização e a automação desta etapa, foi desenvolvido um modelo matemático para calibração que usa feições retas, baseado no modelo dos planos equivalentes, com estimação dos parâmetros pelo método combinado. O modelo foi implementado em linguagem C++ em conjunto com o método convencional que usa as equações de colinearidade, de modo a permitir tanto a calibração com pontos quanto com retas. O método foi testado com dados simulados e dados reais e apresentou resultados satisfatórios, compatíveis com o modelo convencional. Para os experimentos com dados reais, foi ainda implementado um programa de extração de bordas com precisão subpixel. / Abstract: Nowadays, digital cameras have been more and more employed in photogrammetric applications. However, the geometric of common camera is not rigid as metric cameras. Therefore, the need for camera calibration has been increasing; moreover it is important to be frequent. The use of straight lines can lead to an easy and fast camera calibration process due to the promising possibility of automation in the line extraction process. Following this thought, a mathematical model, based on the model of equivalent planes, was developed to include inner orientation parameters, using straight lines. This model was implemented using the unified method of adjustment with weight constraint to the parameters. The implemented program was tested using simulate and real data. The results have shown the developed model is comparable to the conventional one using control points. A feature extraction method aiming sub-pixel precision was implemented as well. / Mestre

Segundo relatório disponibilizado pela World Health Organization (WHO) (WHO, 2015), 1,3 milhões de pessoas morrem todos os anos no mundo devido à acidentes de trânsito. Veículos inteligentes se mostram como uma proeminente solução para reduzir esse drástico número. Por isso, diversos grupos de pesquisa no mundo têm concentrado esforços para o desenvolvimento de pesquisa que viabilize o desenvolvimento desse tipo de tecnologia. Diversos são os requisitos necessários para que um veículo possa circular de forma completamente autônoma. Localização, mapeamento, reconhecimento de semáforos e placas de trânsito são apenas alguns dentre tantos. Para que um veículo trafegue nas vias de forma segura, ele precisa saber onde estão os agentes que coabitam o mesmo espaço. Depois que esses agentes são detectados é necessário predizer suas movimentações de forma a reduzir os riscos de colisão. Neste projeto propôs-se a construção de um sistema que visa detectar agentes (obstáculos) e realizar o rastreamento deles para estimar suas velocidades e localizações enquanto estiverem no campo de visão do veículo autônomo, assim possibilitando realizar o cálculo da chance de colisão de cada um desses obstáculos com o veículo autônomo. O sistema utiliza unicamente a informação provida por uma câmera estereoscópica. Os pontos da cena são agrupados utilizando a informação da 24-vizinhança, disparidade e um valor que corresponde a chance de fazerem parte de um obstáculo. Após o agrupamento, cada grupo é dado como um possível obstáculo, após checar a consistência desses obstáculos por dois frames consecutivos, o grupo, agora considerado um obstáculo passa a ser rastreado utilizando filtro de Kalman (WELCH; BISHOP, 1995) e para checar a correspondência de obstáculos ao longo de toda a sequência é utilizado o algoritmo de Munkres (MUNKRES, 1957). A detecção e o rastreamento foram avaliados quantitativamente e qualitativamente utilizando dados coletados no Campus II da USP de São Carlos, bem como o conjunto de dados KITTI (GEIGER; LENZ; URTASUN, 2012). Os resultados demonstram a eficiência do algoritmo tanto na detecção dos obstáculos como no rastreamento dos mesmos. / According to a report provided by the WHO (World Health Organization) in 2015 (WHO, 2015), 1.3 million people die every year worldwide due to traffic accidents. Intelligent vehicles appear as a prominent solution to reduce this number. Many research groups in the world have been focussing efforts on the development of research in order to enable the development of such technology. There are several requirements for a vehicle be completely autonomous on the roads. Location, mapping, recognition of traffic lights and traffic signs are just a few among many. For safety the vehicle needs to detect all the other elements that are present in the same environment and to estimate their velocity in order to know where they are planning to go to avoid any kind of collision. This project proposes a system to detect obstacles and perform their tracking to estimate their speeds and locations enabling the calculation of the chance of collision of each of these obstacles with the autonomous vehicle. The system only uses the information provided by a stereoscopic camera. The points in the scene are clustered using the 24-neighborhood information, disparity and a value related to the chance of it being part of an obstacle. After the clustering, each cluster is considered a possible obstacle, when the consistence is checked in two frames the cluster becames an obstacle and starts being tracked using Kalman filter (WELCH; BISHOP, 1995), to match obstacles being tracked in the whole sequence the Munkres algorithm (MUNKRES, 1957) is used. The detection and tracking were evaluated qualitatively and quantitatively using data collected in the Campus II of USP in São Carlos and data from KITTI dataset (GEIGER; LENZ; URTASUN, 2012). The results show the algorithms efficiency in obstacle detection and tracking.

Previous red light camera (RLC) studies have shown reductions in violations and overall and right angle collisions, however, they may also result in increases in rear-end crashes (Retting & Kyrychenko, 2002; Retting & Ferguson, 2003). Despite their apparent effectiveness, many RLC studies have produced imprecise findings due to inappropriate study designs and/or statistical techniques to control for biases (Retting & Kyrychenko, 2002), therefore, a more comprehensive approach is needed to accurately assess whether they reduce motor vehicle injury collisions. The objective of this proposal is to assess whether RLC’s improve safety at signalized intersections within Miami-Dade County, Florida. Twenty signalized intersections with RLC’s initiating enforcement on January 1st, 2011 were matched to two comparison sites located at least two miles from camera sites to minimize spillover effect. An Empirical Bayes analysis was used to account for regression to the mean. Incidences of all injury, red light running related injury, right-angle/turning, and rear-end collisions were examined. An index of effectiveness along with 95% CI’s were calculated. During the first year of camera enforcement, RLC sites experienced a marginal decrease in right-angle/turn collisions, a significant increase in rear-end collisions, and significant decreases in all-injury and red light running-related injury collisions. An increase in right-angle/turning and rear-end collisions at the RLC sites was observed after two years despite camera enforcement. A significant reduction in red light running-related injury crashes, however, was still observed after two years. A non-significant decline in all injury collisions was also noted. Findings of this research indicate RLC’s reduced red light running-related injury collisions at camera sites, yet its tradeoff was a large increase in rear-end collisions. Further, there was inconclusive evidence whether RLC’s affected right-angle/turning and all injury collisions. Statutory changes in crash reporting during the second year of camera enforcement affected the incidence of right-angle and rear-end collisions, nevertheless, a novelty effect could not be ruled out. A limitation of this study was the small number of injury crashes at each site. In conclusion, future research should consider events such as low frequencies of severe injury/fatal collisions and changes in crash reporting requirements when conducting RLC analyses.

Northwestern Arctic Canada is one of the most rapidly warming regions in the Arctic (Serreze et al., 2009). Retrogressive thaw slumps (RTS) are one of the most dramatic thermokarst features in permafrost terrain (Kokelj et al., 2013). Many studies have focused on describing the distribution of thermokarst landscapes (i.e., Olefeldt et al., 2016), as well as change in thermokarst terrain over the historical record (i.e., Kokelj and Jorgenson, 2013). However, improved high temporal and spatial resolution monitoring of thaw slump activity is required to enhance our understanding of factors governing their growth. Recent advances in aerial and ground-based Structure from Motion (SfM), a photogrammetry application, allow for temporal and spatial high-resolution characterization of landscape changes. This thesis explores two methods in SfM photogrammetry: 1) aerial imaging using an unmanned aerial vehicle (UAV) and 2) ground-based imaging using stationary multi-camera time-lapse installations, to derive high-resolution temporal and spatial data for change detection. A trend in mean elevation change was produced, and agrees with the RTS behaviour over the study period, which supports the viability of the proposed capture method. The lack of congruency in data range suggests need for further development in terms of analyses and differencing algorithms employed. The proposed method may be feasible for employment in other fields of science in which high temporal resolution change detection is desired. This proof of concept study was conducted at a small slump on the Peel Plateau, NWT, Canada, and aims to enhance understanding of the development and perpetuation of thaw slumps, to better anticipate landscape and ecosystem responses to future climate change.

Navigation and mapping in unknown environments is an important building block for increased autonomy of unmanned vehicles, since external positioning systems can be susceptible to interference or simply being inaccessible. Navigation and mapping require signal processing of vehicle sensor data to estimate motion relative to the surrounding environment and to simultaneously estimate various properties of the surrounding environment. Physical models of sensors, vehicle motion and external influences are used in conjunction with statistically motivated methods to solve these problems. This thesis mainly addresses three navigation and mapping problems which are described below. We study how a vessel with known magnetic signature and a sensor network with magnetometers can be used to determine the sensor positions and simultaneously determine the vessel's route in an extended Kalman filter (EKF). This is a so-called simultaneous localisation and mapping (SLAM) problem with a reversed measurement relationship. Previously determined hydrodynamic models for a remotely operated vehicle (ROV) are used together with the vessel's sensors to improve the navigation performance using an EKF. Data from sea trials is used to evaluate the system and the results show that especially the linear velocity relative to the water can be accurately determined. The third problem addressed is SLAM with inertial sensors, accelerometers and gyroscopes, and an optical camera contained in a single sensor unit. This problem spans over three publications. We study how a SLAM estimate, consisting of a point cloud map, the sensor unit's three dimensional trajectory and speed as well as its orientation, can be improved by solving a nonlinear least-squares (NLS) problem. NLS minimisation of the predicted motion error and the predicted point cloud coordinates given all camera measurements is initialised using EKF-SLAM. We show how NLS-SLAM can be initialised as a sequence of almost uncoupled problems with simple and often linear solutions. It also scales much better to larger data sets than EKF-SLAM. The results obtained using NLS-SLAM are significantly better using the proposed initialisation method than if started from arbitrary points. A SLAM formulation using the expectation maximisation (EM) algorithm is proposed. EM splits the original problem into two simpler problems and solves them iteratively. Here the platform motion is one problem and the landmark map is the other. The first problem is solved using an extended Rauch-Tung-Striebel smoother while the second problem is solved with a quasi-Newton method. The results using EM-SLAM are better than NLS-SLAM both in terms of accuracy and complexity. / LINK-SIC

abstract: Police departments have perceived improved citizen behavior to be a benefit of body-worn cameras (BWC) since their implementation. Often referred to as a civilizing effect, the idea that citizens will become calmer when they know that they are being recorded by an officer is rooted in deterrence theory and self-awareness theory. Deterrence theory states that people will behave properly when they believe punishment will be swift, certain, and severe, while self-awareness theory states that individuals cognizant of their place in society model their actions based on social norms. The presence of a BWC, though, does not guarantee that the citizen is aware they are being recorded. Citizen awareness of the BWC and activation of the BWC are necessary pre-conditions to improved behavior. Current evidence is mixed regarding if BWCs are a catalyst for improved citizen behavior, which is typically measured through reductions in use of force by police and citizen complaints. Using data collected through systematic social observation during police ride-alongs, the author will seek to determine: 1) How often BWCs are activated in police-citizen encounters, 2) How often citizens are aware of BWCs in these encounters, 3) How often citizen behavior changes positively following BWC awareness, and 4) How often citizen behavior changes independent of BWC awareness. This study expands on current research by examining the civilizing effect of BWCs from a transactional standpoint and how citizen behavior changes within an officer-citizen encounter, rather than using a post-interaction metric such as use of force. Despite high BWC activation compliance among the officers within this study, no evidence was found for BWCs having a civilizing effect as the pre-condition of citizen awareness was rarely satisfied. These results could shape policies within departments implementing BWCs hoping to improve officer safety and community relations. Mandatory notification would satisfy the pre-condition of citizen awareness, allowing for the BWC to potentially have a civilizing effect. / Dissertation/Thesis / Masters Thesis Criminology and Criminal Justice 2020

As spacecraft today become increasingly smaller, the demand for smaller components and sensors rises as well. The smartphone, a cutting edge consumer technology, has impressive collections of both sensors and processing capabilities and may have the potential to fill this demand in the spacecraft market. If the technologies of a smartphone can be used in space, the cost of building miniature satellites would drop significantly and give a boost to the aerospace and scientific communities.Concentrating on the problem of spacecraft orientation, this study sets ground to determine the capabilities of a smartphone camera when acting as a star camera. Orientations determined from star images taken from a smartphone camera are compared to those of higher quality cameras in order to determine the associated accuracies. The results of the study reveal the abilities of low-cost off-the-shelf imagers in space and give a starting point for future research in the field.The study began with a complete geometric calibration of each analyzed imager such that all comparisons start from the same base. After the cameras were calibrated, image processing techniques were introduced to correct for atmospheric, lens, and image sensor effects. Orientations for each test image are calculated through methods of identifying the stars exposed on each image. Analyses of these orientations allow the overall errors of each camera to be defined and provide insight into the abilities of low-cost imagers.