@Article{GalvaoBreuSantMour:2013:ViEfHy,
               author = "Galvao, Lenio Soares and Breunig, F{\'a}bio Marcelo and Santos, 
                         Joao Roberto and Moura, Yhasmin Mendes de",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Federal de Santa Maria (UFSM)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)}",
                title = "View-illumination effects on hyperspectral vegetation indices in 
                         the Amazonian tropical forest",
              journal = "International Journal of Applied Earth Observation and 
                         Geoinformation",
                 year = "2013",
               volume = "21",
                pages = "291--300",
                 note = "Setores de Atividade: Outras atividades profissionais, 
                         cient{\'{\i}}ficas e t{\'e}cnicas.",
             keywords = "hyperspectral remote sensing, hyperion, vegetation indices, 
                         PROSAIL, tropical forest, view angle, directional effects, dry 
                         season.",
             abstract = "Because of the pointing capability of the Hyperion/Earth 
                         Observing-One (EO-1) to improve the revisit time of the scene, 
                         temporal series of narrowband vegetation indices (VIs) can be 
                         generated to study the phenology of the Amazonian tropical 
                         forests. In this study, 10 selected narrowband VIs calculated from 
                         Hyperion nadir and off-nadir data and from different view 
                         directions (forward scattering and backscattering) were analyzed 
                         for their sensitivity to view-illumination effects along the dry 
                         season on the Seasonal Semi-deciduous Forest. Data analysis was 
                         also supported by PROSAIL modeling to simulate the spectral 
                         response of this forest type in both directions. Hyperion and 
                         PROSAIL results showed that the Enhanced Vegetation Index (EVI) 
                         and Photochemical Reflectance Index (PRI) were the two more 
                         anisotropic VIs, whereas the Normalized Difference Vegetation 
                         Index (NDVI), Structure Insensitive Pigment Index (SIPI) and the 
                         Vogelmann Red Edge Index (VOG) were comparatively less sensitive 
                         to view-illumination effects. When compared to the other VIs and 
                         because of the greater dependence on the near-infrared (NIR) 
                         reflectance, EVI showed a different spectral behavior. EVI 
                         increased from forward scattering to backscattering and with 
                         decreasing solar zenith angle (SZA) towards the end of the local 
                         dry season, due to reduction in shading and enhancement of the 
                         illumination effects. On the other hand, PRI was higher with 
                         increasing shading in the forward scattering direction, as deduced 
                         from the PROSAIL simulation. Results emphasized the importance of 
                         taking into account bidirectional effects when analyzing temporal 
                         series of VIs collected over tropical forests by imaging 
                         spectrometers with pointing capability or even by multispectral 
                         sensors with large field-of-view (FOV).",
                  doi = "10.1016/j.jag.2012.07.005",
                  url = "http://dx.doi.org/10.1016/j.jag.2012.07.005",
                 issn = "0303-2434",
                label = "lattes: 1646956319628219 3 Galv{\~a}oBreuSantMour:2013:ViEfHy",
             language = "en",
           targetfile = "1-s2.0-S0303243412001432-main-1.pdf",
        urlaccessdate = "02 maio 2024"
}