Ground truth roughness measurement for Sir-C/X-Sar images: a photogrammetric approach in the Montespertoli test site

Several ground truth measurement campaigns have been carried out on significant crop and hillslope portions of the Montespertoli X-SAX/SIR-C test site in order to gather data regarding vegetation cover, land-use, soil moisture and soil roughness. A new technique for the evaluation of the latter is presented, based on a completely automated terrestrial photogrammetric method. On chosen transects along meaningful directions on hillslopes of the area, a series of digital photographic stereopairs were taken with the help of a special double-camera instrument realized for the purpose. Afterwards a series of 1 by 1 meter DTMs were generated by the modeling software and then connected to each other. For the measurement and parameterization of the relative soil roughness the whole surveyed three-dimensional surface was considered and the classical statistical parameters were replaced with those generated by geostatistic methods in the framework of a self-similar surface characterization.