ESTCB - Escola Superior de Tecnologia
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Browsing ESTCB - Escola Superior de Tecnologia by Author "Afonso, João M.S."
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- Detecting wear and tear in pedestrian crossings using computer vision techniques: approaches, challenges, and opportunitiesPublication . Rosa, Gonçalo J.M.; Afonso, João M.S.; Gaspar, Pedro Dinis; Soares, V.N.G.J.; Caldeira, J.M.L.P.Pedestrian crossings are an essential part of the urban landscape, providing safe passage for pedestrians to cross busy streets. While some are regulated by timed signals and are marked with signs and lights, others are simply marked on the road and do not have additional infrastructure. Nevertheless, the markings undergo wear and tear due to traffic, weather, and road maintenance activities. If pedestrian crossing markings are excessively worn, drivers may not be able to see them, which creates road safety issues. This paper presents a study of computer vision techniques that can be used to identify and classify pedestrian crossings. It first introduces the related concepts. Then, it surveys related work and categorizes existing solutions, highlighting their key features, strengths, and limitations. The most promising techniques are identified and described: Convolutional Neural Networks, Histogram of Oriented Gradients, Maximally Stable Extremal Regions, Canny Edge, and thresholding methods. Their performance is evaluated and compared on a custom dataset developed for this work. Insights on open issues and research opportunities in the field are also provided. It is shown that managers responsible for road safety, in the context of a smart city, can benefit from computer vision approaches to automate the process of determining the wear and tear of pedestrian crossings.
- Técnicas de visão computacional para deteção de passadeiras pedonais em mau estado de conservaçãoPublication . Rosa, Gonçalo J.M.; Afonso, João M.S.; Soares, Vasco N.G.J.; Caldeira, J.M.L.P.Este estudo visa validar, avaliar e comparar diferentes técnicas de visão computacional para detetar passadeiras pedonais em mau estado de conservação, muitas vezes quase imperceptíveis tanto para automobilistas como para peões. Apresenta os conceitos relacionados com a temática e as soluções apontadas na literatura, discute os pontos fortes e limitações das mesmas e identifica pontos em aberto. Após esta análise, apresenta uma avaliação de desempenho das técnicas mais promissoras para solução deste problema.
- The development of a prototype solution for detecting wear and tear in pedestrian crossingsPublication . Rosa, Gonçalo J.M.; Afonso, João M.S.; Gaspar, Pedro Dinis; Soares, Vasco N.G.J.; Caldeira, J.M.L.P.Crosswalks play a fundamental role in road safety. However, over time, many suffer wear and tear that makes them difficult to see. This project presents a solution based on the use of computer vision techniques for identifying and classifying the level of wear on crosswalks. The proposed system uses a convolutional neural network (CNN) to analyze images of crosswalks, determining their wear status. The design includes a prototype system mounted on a vehicle, equipped with cameras and processing units to collect and analyze data in real time as the vehicle traverses traffic routes. The collected data are then transmitted to a web application for further analysis and reporting. The prototype was validated through extensive tests in a real urban environment, comparing its assessments with manual inspections conducted by experts. Results from these tests showed that the system could accurately classify crosswalk wear with a high degree of accuracy, demonstrating its potential for aiding maintenance authorities in efficiently prioritizing interventions.