Publications

Vaudour, E.; Noirot-Cosson, P. E.; Membrive, O. (2015). Early-season mapping of crops and cultural operations using very high spatial resolution Pleiades images. INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION, 42, 128-141.

Abstract
The aim of this study was to assess the contribution of very high spatial resolution (VHSR) Pleiades images to both early season crop identification and the mapping of bare soil surface characteristics due to cultural operations. The study region covering 21 km(2) is located west of the pen-urban territory of the Versailles plain and the Alluets plateau (Yvelines, France). About 100 cropped fields were observed on the ground synchronously with two Pleiades images of 3 and 24 April 2013 and one SPOT4 image of 2 April 2013. The GIS structuring of these field data along with vector information about field boundaries was used for delimitating both training and test zones for the support vector machine classifier with polynomial function kernel (pSVM). The pSVM was computed on the spectral bands and NDVI for both single-date Pleiades and the bi-temporal Pleiades pair. For the single-date classifications of crops, the overall per-pixel accuracy reached 87% for the SPOT4 image of 2 April (6 classes), 79% for the Pleiades image of 3 April (6 classes) and 82% for that of 24 April (7 classes). At the earlier date (2-3 April), the Pleiades image very well discriminated cultural operations (>77%, user's or producer's accuracies) as well as fallows and grasslands, while winter cereals and rapeseed were better discriminated by the SPOT4 image winter cereals (>70%, user's or producer's accuracies). As Pleiades images revealed within-field spatial variations of early phenological stages of winter cereals that could be critical for adjusting management of zones with delayed development during the growing season, they brought information complementary to multispectral images with high spatial resolution. For the bi-temporal Pleiades image, the overall per-pixel accuracy was about 80% (7 classes), winter crops, grasslands and fallows being very well detected while confusions occurred between spring barley at initial stages (2-3 leaves) and bare soils prepared for other spring crops. Using an additional validation field set covering similar to 1/3 of the study area croplands, the crop map resulting from the bi-temporal Pleiades pair achieved correct crop prediction for about 89.7% of the validation fields when considering composite classes for winter cereals and for spring crops. Early-season Pleiades images therefore show a considerable potential for anticipating regional crop patterns and detecting soil tillage operations in spring. (C) 2015 Elsevier B.V. All rights

DOI:
10.1016/j.jag.2015.06.003

ISSN:
0303-2434