Calibration and validation data for cropland classification over two sites in 2013

The data are for two sites located in Belgium (top left: 51.00°N, 4.50°E and bottom right: 49.60°N, 5.80°E) and South Africa (top left: 26.85°S, 24.55°E and bottom right: 30.74°S, 29.77°E).. They each cover an area of 60 km x 60 km and are dominated by cropland. For both sites, a 20-m multi-sensor time series consisting of SPOT-4 (Take 5) data and Landsat-8 data spanning from February to December 2013 were at hand. For Landsat, only reflectances in the green, red, near infra-red and short wave infrared wavelengths were considered. The SPOT-4 and Landsat-8 images were processed with the Multi-sensor Atmospheric Correction and Cloud Screening processor. The time series were gap filled using linear interpolation and three spectral-temporal features were extracted. These spectral-temporal features correspond to reflectance composites at the minimum and the maximum of normalized difference vegetation index as well as the mean reflectance over the season. Such features were shown to provide high discrimination power between cropland and non-cropland areas.<br>Ground truth observations from the corresponding growing season supplemented the satellite image time series. In Belgium, field polygons were sourced from the Land Parcel Identification System and non-cropland polygons were digitized based on very high resolution imagery. In South Africa, both cropland and non-cropland objects were both digitized based on very high resolution data. These reference data sets were evenly split at the polygon level into two independent sets to be used for calibration and validation, respectively.