title: Assessment of Unmanned Aerial Vehicles Imagery for Quantitative Monitoring of Wheat Crop in Small Plots.
abstract: This paper outlines how light Unmanned Aerial Vehicles (UAV) can be used in remote sensing for precision farming. It focuses on the combination of simple digital photographic cameras with spectral filters, designed to provide multispectral images in the visible and near-infrared domains. In 2005, these instruments were fitted to powered glider and parachute, and flown at six dates staggered over the crop season. We monitored ten varieties of wheat, grown in trial micro-plots in the South-West of France. For each date, we acquired multiple views in four spectral bands corresponding to blue, green, red, and near-infrared. We then performed accurate corrections of image vignetting, geometric distortions, and radiometric bidirectional effects. Afterwards, we derived for each experimental micro-plot several vegetation indexes relevant for vegetation analyses. Finally, we sought relationships between these indexes and field-measured biophysical parameters, both generic and date-specific. Therefore, we established a robust and stable generic relationship between, in one hand, leaf area index and NDVI and, in the other hand, nitrogen uptake and GNDVI. Due to a high amount of noise in the data, it was not possible to obtain a more accurate model for each date independently. A validation protocol showed that we could expect a precision level of 15% in the biophysical parameters estimation while using these relationships.
authors.affiliation: CIRAD, UMR TETIS, 500 Rue J.-F. Breton, 34093 Montpellier Cedex 5, France. camille.lelong@cirad.fr.
authors.forename: Camille C D
authors.initials: CC
authors.lastname: Lelong
authors.affiliation: INRA, UMR 1248 AGIR, Chemin de Borde Rouge, BP52627, 31326 Castanet Tolosan Cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Burger
authors.affiliation: Nev@ntropic, 16 bis Avenue du Quatorze Juillet, 97300 Cayenne, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Jubelin
authors.affiliation: L'Avion Jaune, Minéa Incubation, 361 Rue J.-F. Breton, BP5095, 34196 Montpellier Cedex 5, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Roux
authors.affiliation: Cemagref, UMR TETIS, 500 Rue J.-F. Breton, 34093 Montpellier Cedex 5, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Labbé
authors.affiliation: INRA, UMR 1114 EMMAH, Domaine St Paul, Site Agroparc, 84914 Avignon Cedex 9, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Baret
keywords: Imagery; Multispectral; Precision Farming; UAV