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Percorrer por autor "Pinto, Luis"

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  • Asymmetric 3D video coding using regions of perceptual relevance
    Publication . Pinto, Luis; Assunção, Pedro
    This paper proposes an extension of the concept of asymmetric coding by introducing region-based asymmetry in the spatial dimension of stereoscopic video. The method relies on stereo image regions with different relevance for 3D perception defined by spatial binary masks. It is demonstrated that to a certain extent, regions with lower perceptual relevance can be encoded with lower quality than the remaining ones without harming the perceived quality. 3D video streams with different asymmetric quality combinations were produced and then evaluated through subjective testing. The results show that it is possible to further exploit traditional asymmetric coding while maintaining the same perceptual quality. Depending on the sequence content, this work leads to the conclusion that it is possible to reduce the bitrate of the auxiliary view up to 20 percent without being perceived by users.
    2012-12Comunicação em conferência Acesso restrito Ver mais
  • Drones for litter mapping: An inter-operator concordance test in marking beached items on aerial images
    Publication . Andriolo, Umberto; Gonçalves, Gil; Rangel-Buitrago, Nelson; Paterni, Marco; Bessa, Filipa; Gonçalves, Luisa M. S.; Sobral, Paula; Bini, Monica; Duarte, Diogo; Fontán-Bouzas, Ángela; Gonçalves, Diogo; Kataoka, Tomoya; Luppichini, Marco; Pinto, Luis; Topouzelis,Konstantinos; Vélez-Mendoza, Anubis; Merlino, Silvia
    Unmanned aerial systems (UAS, aka drones) are being used to map macro-litter on the environment. Sixteen qualified researchers (operators), with different expertise and nationalities, were invited to identify, mark and categorize the litter items (manual image screening, MS) on three UAS images collected at two beaches. The coefficient of concordance (W) among operators varied between 0.5 and 0.7, depending on the litter parameter (type, material and colour) considered. Highest agreement was obtained for the type of items marked on the highest resolution image, among experts in litter surveys (W = 0.86), and within territorial subgroups (W = 0.85). Therefore, for a detailed categorization of litter on the environment, the MS should be performed by experienced and local operators, familiar with the most common type of litter present in the target area. This work provides insights for future operational improvements and optimizations of UAS-based images analysis to survey environmental pollution.
    2021-08Artigo científico Acesso aberto Ver mais