Abstract
The modified cosine correction of topographical effects, which subtracts an offset component before applying the cosine law of solar incidence angle, seems to work well for satellite images with high sun elevation and with high geometric accuracy. The adequate offset component for the correction, however, tend to be bigger than we expect from the radiative transfer simulation, in particular for infrared bands. In this paper, we improve the modified cosine correction by introducing C factor which corresponds to the amount of diffuse sky irradiance and reflected irradiance from adjacent slopes. Although the C factor is assumed to be a constant in conventional C correction, we calculate the diffuse sky irradiance and reflected irradiance for each pixel using digital elevation model. We apply this method to the actual Landsat image (Band 5) to show its effectiveness.
