This paper describes the principles and methodology to express bidirectional reflection （BDR） properties of ground targets by using direct radiative remotely sensed image under the support of GIS. The principles and theoretical basis is that the difference of slope and its orientation changes the relative position of pixel ground

sun

and satellite remote sensor and results in the variety of solar direct radiance of similar pixels. The difference reflect the bidirectional reflectance. The bidirectional reflectance could be studied through the analysis of the difference and its relation with sun position and satellite position under the support of GIS

using satellite remotely sensed direct radiance digital images.