站长说的很对,补充一下: :@BAiKa[wa
Normal Vector h(q,-')l_
The Normal Vector is a vector in 3D space that is used to orient the projection eI?|Ps{S
plane for the irradiance map. The plane is defined to be perpendicular to the #2`ST=#
Normal Vector, and the irradiance incident on the selected surface is projected F1m 1%
onto this plane. When the map is displayed, the normal vector is pointing toward `/W6,]
you. ,t"?~Hl".
Up Vector :<t%Sf
The Up Vector is a vector in 3D space that is used to orient the projection plane Z>0a?=1[
for the irradiance map. The plane is defined so that the Up Vector is parallel to the v:2*<;
vertical side of the plane. The irradiance incident on the selected surface is Un[olp
projected onto this plane. When the map is displayed, the up vector will point >3{#S:
toward the top of the screen.