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<field name="value">Vélez Martín, Sergio</field>
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<field name="value">Poblete Echeverría, Carlos</field>
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<field name="value">Rubio Cano, José Antonio</field>
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<field name="value">Barajas, Enrique</field>
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<field name="value">2025-01-29T09:10:11Z</field>
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<field name="value">10.20870/oeno-one.2021.55.4.4639</field>
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<field name="value">A few decades ago, farmers could precisely monitor their croplands just by walking over the fields, but this task becomes more difficult as farm size increases. Precision viticulture can help better understand the vineyard and measure some key structural parameters, such as the Leaf Area Index (LAI). Remote Sensing is a typical approach to monitoring vegetation which measures the spectral information directly emitted and reflected from vegetation. This study explores a new method for estimating LAI which measures the projected shadows of plants using UAV (unmanned aerial vehicle) imagery. A flight mission over a vineyard was scheduled in the afternoon (15:30 to 16:00 solar time), which is the optimal time for the projection of vine shadows on the ground. Real LAI was measured destructively by removing all the vegetation from the area. Then, the projected shadows in the image were detected using machine learning methods (k-means and random forest) and analysed at pixel level using a customised R code. A strong linear relationship (R² = 0.76, RMSE = 0.160 m² m-2 and MAE = 0.139 m² m-2) was found between the shaded area and the LAI per vine. This is a quick and simple method, which is non-destructive and gives accurate results; moreover, flights can be scheduled during other periods of the day than solar noon, such as in the morning or afternoon, thus enabling pilots to extend their working day. Therefore, it may be a viable option for determining LAI in vineyards trained on Vertical Shoot Positioned (VSP) systems.</field>
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<field name="value">This study was possible thanks to the financial support of Junta de Castilla y León (Spain), the project INIA RTA2014- 00077-C02, FPI-INIA2016-017 and FEDER funding.</field>
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<field name="value">International Viticulture and Enology Society</field>
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<field name="value">OENO One. 2021, V. 55, n. 4, p. 159-180</field>
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<field name="value">Leaf area index</field>
<field name="value">Shadow detection</field>
<field name="value">Image analysis</field>
<field name="value">Precision agriculture</field>
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<field name="value">Spatial variability</field>
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<field name="value">Estimation of Leaf Area Index in vineyards by analysing projected shadows using UAV imagery</field>
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