The SPOT VEGETATION program was developed
jointly by France, the European Commission, Belgium,
Italy, and Sweden. Since April 1998, this large field of view
sensor has been operational on board the SPOT-4 earth
observation satellite system (Archard et al., 1994). We
obtained 4 years (1998 to 2001) of NDVI data free from theVEGETATION products website (http://www.free.vgt.
vito.be/).
SPOT has four spectral bands (Band 1: 430–470 nm;
Band 2: 610–680 nm; Band 3: 780–890 nm; and Band 4:
1.58–1.7 Am). The wavelength ranges of both bands used to
compute NDVI are narrower than those of AVHRR. There is
at least one observation daily acquired at 10:30 local solar
time for latitudes above 328. The objectives of the
VEGETATION system are to provide accurate measurements
of basic characteristics of vegetation canopies on an
operational basis, either for scientific studies involving both
regional and global scale experiments over long time
periods, or for systems designed to monitor important
vegetation resources. Its large field of view (up to F608
cross-track) results in a strong dependency on surface
reflectance on the sun-target-sensor geometry. The common
Maximum Value Compositing (MVC) method was used to
improve the NDVI data, despite some limitations of the
method.