Assessment of vegetational indices applied to sugarcane monitoring using Rapideye images
Rapideye sensor have been operating since 2009 and was one of the first multispectral (5 bands) sensors to operate as part of a satellite constellation (5 satellites), able to provide a massive stock of images with singular synoptic (~5 days) and spatial capabilities (5m). However, so far the Rapideye unique characteristic is still underused, precisely, its Red Edge band (690-730) and possible applications to agricultural mapping considering crop biophysical compounds. The Red Edge band is spectrally located between the Red band, where chlorophyll presence causes strong absorption of light, and the Near Infrared (NIR) band, which has a strong reflection associated with the leaf cell structure. In order to explore the spectral characteristics of the Rapideye images we evaluated the sensor performance at the sugarcane crop over five different crop management (i.e. irrigated, non-irrigated, meiosi, conventional management and Coopercitrus management), by comparison between two band ratios: NDVI (Normalized Difference Vegetation Index), that uses Red and NIR bands; and NDRE (Normalized Difference Red Edge Index), which uses the Red and Red Edge bands. Through the use of NDRE index was possible to map discreet and important spatial variations of chlorophyll content in the intra experimental fields.