Landsat ETM+ mosaic of northern Canada - Land Cover
This product resulted from a joint collaboration between the Climate Change and Groundwater Programs at the Earth Sciences Sector of Natural Resources Canada, and was supported by the Canadian Space Agency through the Government Related Initiatives Program (GRIP) proposal 'EO-based view of our landmass in support of northern development'. A mosaic of northern Canada above the tree line was produced from public domain Landsat ETM+ level L1G bands 3, 4 and 5 ortho-imagery available through the Centre for Topographic Information of Natural Resources Canada. Radiometric normalization was necessary due to different acquisition times among the 446 individual scenes in this mosaic. A highly automated radiometric normalization technique was performed to match scenes to a common radiometric reference consisting of a coarse (1km) apparent reflectance 2000 growing season composite image generated at CCRS from VGT-S01 data from SPOT's VEGETATION sensor. Normalization involved resampling individual Landsat scenes to 1 km resolution using the VGT point spread function and generating band-specific normalization coefficients between Landsat and VGT using a robust regression technique called Thiel-Sen. This technique has been shown to produce optimal consistency among Landsat scenes in Olthof et al., 2005, and is highly automated allowing production of a mosaic of this size. These data are available in geo-tiff format with 57173 columns and 32914 rows at 90 m resolution obtained by resampling 30 m Landsat data. More information on the processing chain used to generate these data are available in Olthof, Butson, Fernandes, Fraser, Latifovic and Orazietti (2005). Landsat ETM+ mosaic of northern Canada. Canadian Journal of Remote Sensing (accepted).