站长说的很对，补充一下： f(EO|d^u
Normal Vector a!j{A?7Kw.
The Normal Vector is a vector in 3D space that is used to orient the projection ^= kr`5
plane for the irradiance map. The plane is defined to be perpendicular to the _GoFwVO
Normal Vector, and the irradiance incident on the selected surface is projected
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onto this plane. When the map is displayed, the normal vector is pointing toward }? CKE<#%
you. QqC-ztz
Up Vector !@h)3f]`1G
The Up Vector is a vector in 3D space that is used to orient the projection plane $}H,g}@0
for the irradiance map. The plane is defined so that the Up Vector is parallel to the \Jwc[R&x
vertical side of the plane. The irradiance incident on the selected surface is (V}?y:)
projected onto this plane. When the map is displayed, the up vector will point (F#2z\$;
toward the top of the screen.
