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Pinty, B., Widlowski, J., Gobron, N., Verstraete, M.M., Diner, D.J., Davis, A B. (2003). Towards Land Structure Parameters from Multi-angular Remote Sensing Data. Eos Trans. AGU, 84(46), Fall Meet. Suppl. 2003, Abstract # B12G-04

Recent studies have highlighted the importance of vegetation structure, both in the context of landscape dynamics and with regard to ecosystem productivity. Quasi-simultaneous multi-spectral and multi-directional remote sensing measurements from space, as provided by the Multi-angle Imaging SpectroRadiometer (MISR), offer new and unique opportunities to document the angular variations of land surface reflectances. The geophysical interpretation of such reflectance anisotropy patterns over terrestrial surfaces has only recently permitted to relate these signatures in a quantified manner to the structure and heterogeneity of the underlying surface. This contribution outlines simple physical principles supporting the interpretation of the anisotropy of spectral radiances exiting terrestrial surfaces in terms of a signature of surface heterogeneity. The shape of the anisotropy function is represented with two model parameter values which may be mapped and interpreted in their own right. Beyond the information about the heterogeneity of the surface, the value of one of these parameters also permits identifying geophysical conditions where the surface heterogeneity becomes significant. Structure functions and singularity measures can be employed to describe the non-stationary and intermittent behaviour of geophysical fields. This approach is applied on synthetic height field measurements of a large variety of vegetation canopies. The joint analysis of the shape of the anisotropy function together with the height fields yields remarkable patterns of organization: It is possible for multiangular instruments, like MISR, to deliver information about the type of surface heterogeneity at the subpixel scale, that is in agreement with canopy structure characterizations obtained by other means.

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Updated: 14-Jan-2005