Wang Jianmin;Cao Xin;Chen Jin;Jia Xiuping

 

[Wang, Jianmin; Cao, Xin; Chen, Jin] Beijing Normal Univ, State Key Lab Earth Surface Proc & Resource Ecol, Beijing 100875, Peoples R China.

[Wang, Jianmin] Ohio State Univ, Dept Geog, Columbus, OH 43210 USA.

[Jia, Xiuping] Univ New S Wales, Sch Engn & Informat Technol, Canberra, ACT 2600, Australia.

 

ABSTRACT: Multiple scattering within a mixed pixel results in a nonlinear effect on the measured spectra in remotely sensed imagery. This study provides a quantitative assessment of multiple scattering in the reflectance of semiarid shrublands and explores its relationship to the characteristics of shrubs (density and height) and imaging parameters (wavelength and viewing angles). Field measurements were conducted at the southern fringe of the Otindag Sandy Land in China. A Monte Carlo ray tracing model, the Forest LIGHT interaction model (FLIGHT), was applied to simulate the multiple scattering results. FLIGHT simulation results were first evaluated against field measurements and then compared with a Landsat-8 OLI image. Results show that: 1) the contribution of multiple scattering to the spectra of a scene increases linearly with the fractional cover of vegetation and crown height; 2) in general, multiple scattering has a stronger effect on the near-infrared (NIR) domain than on the visible bands; 3) shadows significantly strengthen the multiple scattering effect, specifically within the visible bands; and 4) 80 to 100% of the total multiple scattering is caused by the second-order scattering within the visible bands and 60% to 90% within the NIR band. This study helps to improve our understanding of the multiple scattering effect and to select between linear and nonlinear spectral unmixing models to solve the abundances of shrubs and soil in mixed pixels.

Published in IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING. 2015,53(9):4910-4921, DOI: 10.1109/TGRS.2015.2413409