If there is no horizontal area (or the area with the 
known slope) on the photos , the value of brightness for it 
can be obtained by calculations. 
from the angles of incidence we can come to the matrix 
of heights from which the map of relief in isolines can be 
made. Fig.1 shows the geometry of radiation of an elemen - 
tary section of surface under two positions of the Sun. 
i t , ¿2 are the angles of incidence on inclined section of 
surface, A o i > A=>2 are the azimuthes of the Sun, A is the 
azimuth of the normal to the section of surface relative to 
the Sun vertical plane on the first photo, S is the incli - 
nation of the section of surface to the horizontal plane, 
From consideration of the spherical A JIB C and A JfBD 
the following relationships can be obtained 
Fig.1 Geometry of radiation of elementary 
section of surface. 
H Q is the normal to horizontal plane; tl is the normal to 
inclined section of surface, t 01 , l 02 are angles of in 
cidence of sunrays falling on horizontal section of surface 
COS i Q2 - Cos j 01 • cos JIB 
cos JIB= Cos i 0l ■ cos i n + sin v, Sin L o Z Cos ( 
where