站长说的很对，补充一下： 2uJNc!&
Normal Vector BCj`WF@8l{
The Normal Vector is a vector in 3D space that is used to orient the projection N$=(1`zM=
plane for the irradiance map. The plane is defined to be perpendicular to the ,Z zB#\
Normal Vector, and the irradiance incident on the selected surface is projected STFQ";z$
onto this plane. When the map is displayed, the normal vector is pointing toward +
d+ hvwEM
you. =!pu+&I 9
Up Vector
l0:e=q2Ax
The Up Vector is a vector in 3D space that is used to orient the projection plane Z1)jRE2dl
for the irradiance map. The plane is defined so that the Up Vector is parallel to the :{TmR3.
vertical side of the plane. The irradiance incident on the selected surface is 3<e(@W}n-M
projected onto this plane. When the map is displayed, the up vector will point i -:8TfI,
toward the top of the screen.
