This article presents a method of calculating spatial object’cahracteristic.The solar irradiation and earth background radiation are calculated with a simplified model.The bidirectional reflectance distribution function(BRDF) links the solar irradiation and light scattering from the object and effectively describes the scattering characteristics and the spectral characteristics.A model on spatial target’s scattering characteristics invisible is built by choosing appropriate models of BRDF and using the radi...