站长说的很对，补充一下： t>GLZzO
Normal Vector f9XO9N,hE:
The Normal Vector is a vector in 3D space that is used to orient the projection h9w^7MbO
plane for the irradiance map. The plane is defined to be perpendicular to the )7 "DR+;:
Normal Vector, and the irradiance incident on the selected surface is projected &R FM
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onto this plane. When the map is displayed, the normal vector is pointing toward us,,W(q
you. ~K#_'Ldrd
Up Vector \3(| c#c
The Up Vector is a vector in 3D space that is used to orient the projection plane ? CW^*S o
for the irradiance map. The plane is defined so that the Up Vector is parallel to the q MdtJ(gq
vertical side of the plane. The irradiance incident on the selected surface is t2%@py*bU
projected onto this plane. When the map is displayed, the up vector will point _ KhEwd
toward the top of the screen.
