站长说的很对，补充一下： -PNi^
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Normal Vector QWrIa1.JC
The Normal Vector is a vector in 3D space that is used to orient the projection LHs- &
plane for the irradiance map. The plane is defined to be perpendicular to the 2 \^G['9
Normal Vector, and the irradiance incident on the selected surface is projected c |>=S)|
onto this plane. When the map is displayed, the normal vector is pointing toward di~]HUZh)
you. K)\(wxv
Up Vector e]lJqC
The Up Vector is a vector in 3D space that is used to orient the projection plane |u@+`4o
for the irradiance map. The plane is defined so that the Up Vector is parallel to the >Bc> IO
vertical side of the plane. The irradiance incident on the selected surface is O^5U B~
projected onto this plane. When the map is displayed, the up vector will point ;{|X,;s
toward the top of the screen.
