Potencial de mosaicos mensais DNB-VIIRS para detecção de atividades humanas e áreas urbanizadas na Amazônia Brasileira - um estudo no Sudoeste do Pará.

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This paper explores nighttime Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) monthly composites product, from NOAA National Geophysical Data Center, to detect evolution of human activities and urbanized areas in Brazilian Amazon. DNBs from 2014 (Aug), 2015 (Sep) and 2016 (Aug) were first clipped to Brazilian limits, in order to encompass the study area: 16 municipalities in the southwestern of Para state. After a histogram matching between DNBs, the images were segmented to discriminate nighttime lights from the background. In a GIS, vectorization over the segmented images generated the polygons of nighttime lights with topology for each DNB. These polygons were then considered stable lights if they: a) presented any intersection with Urban Area class mapped for TerraClass 2014 Project; or b) presented any intersection with one of the others DNBs nighttime polygons. The results showed an unexpected general downward trend in area and number of DNB stable nighttime lights polygons for the Para state. However, it was possible to verify local differences for the study area: municipalities where the urbanized area increased, and municipalities that were affected by construction of Belo Monte Hydroelectric power plant. The best analysis was performed considering specific nighttime lights polygons, detecting of small villages, communities and mining, and the false-positive detections related to savanna and forest in Novo Progresso region. DNB VIIRS presented a high potential to monitor human activities and urbanization processes, although it requires specific and automated methods for image inter-calibration and stable lights extraction.