站长说的很对，补充一下： dKTAc":-}
Normal Vector W(4?#lA2W
The Normal Vector is a vector in 3D space that is used to orient the projection 1W <_5 j_
plane for the irradiance map. The plane is defined to be perpendicular to the r['C.S6
Normal Vector, and the irradiance incident on the selected surface is projected XqH<)B
]
onto this plane. When the map is displayed, the normal vector is pointing toward aW$nNUVD
you. lB~ '7r`
Up Vector :
X|7l?{xW
The Up Vector is a vector in 3D space that is used to orient the projection plane iZ\z !tH R
for the irradiance map. The plane is defined so that the Up Vector is parallel to the a\_,_psK
vertical side of the plane. The irradiance incident on the selected surface is lFY8^#@
projected onto this plane. When the map is displayed, the up vector will point j1+Y=@MA
toward the top of the screen.
