Abstract: By using transporting mechanism to correct topographic radiation, we can fully consider direct solar radiance, sky diffuse radiance and near surface reflectance radiance, and get a better result. The key factor that determines topographic correction result is accurate extraction of shadow factor. The article use DEM method and histogram threshold segmentation method to compute shadow factor of the same area of SPOT-5 panchromatic imagery, and then use the same radiation transmission model to correct topographic radiation. By contrast, the result that using the histogram threshold method is better than DEM method when DEM accuracy is not high enough, and these have fully proved its value and advantage.

Key words: radiative transfer, shadow factor, topographic correction