站长说的很对，补充一下： G0%},Q/
Normal Vector uH{o JSrK
The Normal Vector is a vector in 3D space that is used to orient the projection 52,[d P,g
plane for the irradiance map. The plane is defined to be perpendicular to the iW%~>`tT
Normal Vector, and the irradiance incident on the selected surface is projected HPryq )z
onto this plane. When the map is displayed, the normal vector is pointing toward &9Kni/
you. T
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Up Vector =;Q:z^S
The Up Vector is a vector in 3D space that is used to orient the projection plane gpw,b V
for the irradiance map. The plane is defined so that the Up Vector is parallel to the Xb<> AzEM
vertical side of the plane. The irradiance incident on the selected surface is
/\. [@]
projected onto this plane. When the map is displayed, the up vector will point .Gt_~x
toward the top of the screen.
