  Precision agriculture is considered to be a fundamental approach in pursuing
a low-input, high-efficiency, and sustainable kind of agriculture when
performing site-specific management practices. To achieve this objective, a
reliable and updated description of the local status of crops is required.
Remote sensing, and in particular satellite-based imagery, proved to be a
valuable tool in crop mapping, monitoring, and diseases assessment. However,
freely available satellite imagery with low or moderate resolutions showed some
limits in specific agricultural applications, e.g., where crops are grown by
rows. Indeed, in this framework, the satellite's output could be biased by
intra-row covering, giving inaccurate information about crop status. This paper
presents a novel satellite imagery refinement framework, based on a deep
learning technique which exploits information properly derived from high
resolution images acquired by unmanned aerial vehicle (UAV) airborne
multispectral sensors. To train the convolutional neural network, only a single
UAV-driven dataset is required, making the proposed approach simple and
cost-effective. A vineyard in Serralunga d'Alba (Northern Italy) was chosen as
a case study for validation purposes. Refined satellite-driven normalized
difference vegetation index (NDVI) maps, acquired in four different periods
during the vine growing season, were shown to better describe crop status with
respect to raw datasets by correlation analysis and ANOVA. In addition, using a
K-means based classifier, 3-class vineyard vigor maps were profitably derived
from the NDVI maps, which are a valuable tool for growers.
