站长说的很对，补充一下： i @C].X
Normal Vector yg `j-9[8
The Normal Vector is a vector in 3D space that is used to orient the projection aEFJ;n7m
plane for the irradiance map. The plane is defined to be perpendicular to the X@'u y<tI-
Normal Vector, and the irradiance incident on the selected surface is projected Y#]+Tm (+
onto this plane. When the map is displayed, the normal vector is pointing toward 1A ?W:'N
you. ~xbe~$$Q@
Up Vector Gk.
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The Up Vector is a vector in 3D space that is used to orient the projection plane g%ndvdb m
for the irradiance map. The plane is defined so that the Up Vector is parallel to the ,MdV;j ~"'
vertical side of the plane. The irradiance incident on the selected surface is F <ZYh
projected onto this plane. When the map is displayed, the up vector will point c%^7!FSg
toward the top of the screen.
