AfSIS has produced large-area mosaics of radiometrically calibrated, orthorectified LandsatMSS,TM and ETM+ images. We have also developed SRTM terrain model derivatives (e.g. terrain units, slopes, curvatures, contributing areas, compound topographic and erosion/deposition indices and watershed delineations).

View and download processed SRTM data here.

Substantial effort has been devoted to assembling and harmonizing satellite images, satellite image time series and digital terrain models. The resulting base maps are needed as spatial covariates for soil mapping, but can also be used for other mapping and modeling purposes. For example, Landsat images can be used for land cover change detection and estimation of ecosystem carbon stocks.

The figure to the right shows the locations of 663 Landsat scenes that are needed to map the entire project area at a resolution of 28.5 by 28.5 meters. While a complete archive of Landsat images for the study area is freely available from landsat.org, the data need to be radiometrically calibrated, orthorectified and mosaiced to be useful for large-area soil mapping. Similarly, Shuttle Radar Topography (SRTM, v.3) data at 90 by 90 m resolution are currently available for all of Africa (http://srtm.csi.cgiar.org), but has been processed further to derive terrain models suitable for soil mapping.

Read review of 30 m ASTER data here.

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