Analysis of Atmospheric and Topographic Effects on Landsat TM Imagery

摘要

By using digital terrain model, the topographic effects on the satellite Image are analysed. The radiative transfer code 6S reveals that the altitude effects of path radiancee is negligible for infrared bands, but it must be corrected in visible bands. The analysis of actual Landsat TM image supporte this finding. Next we examine the cosine law of solar Incident angle. The law is more apparent in infrared band than visible band. Based on these finding, we propose the effective correction algorithm for the satellite data with high sun elevation angle. In the case of low sun elevation anglewith wide shadowed region, we have to take sky light and irradiance from neigbor pixels into consideration. It is emphasized that accurate DEM is indispensable not only for ortho-rectification but also for cosine law correction.