637 
1 soil surface, 
tal surface is 
il reflectance 
lunation and 
ification. The 
Hite scanners 
Royer at al., 
explained by 
ices, i.e., soil 
effects which 
1987; Cooper 
1985; Pechet 
f soil surface 
¡flective near- 
:rived version 
isotropic soil 
tduced by the 
r proportional 
ams on these 
ong the solar 
) and vertical 
he horizontal 
he azimuthal 
sses isotropic 
structure are 
changes with 
( 1 ) 
of the given 
Tg, Sg). The 
le linear sub- 
, and also the 
elation to the 
e about wave 
NADIR VIEWING 
( 2 ) 
solar azimuth 
s 0 when the 
do not reach 
»rtional to Epj 
f an isotropic 
d soil surface 
Figure 1. Geometry of the illuminated soil surface along the solar principal plane with sunlit (I) and shaded (S) 
sub-segments of the given spheroid (Is, Ss), the adjoining spheroids (la, Sa) and the ground between the 
spheroids (Ig, Sg), situated at angles pi. Symbols r f and r b describe the radii of the basic view distance.