站长说的很对，补充一下： g:g>;" B
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Normal Vector "e"`Or
The Normal Vector is a vector in 3D space that is used to orient the projection ^ytd~iK8
plane for the irradiance map. The plane is defined to be perpendicular to the N_0O"" d
Normal Vector, and the irradiance incident on the selected surface is projected 2~)]E#9
onto this plane. When the map is displayed, the normal vector is pointing toward I}=}S"v
you. = Dg D&_
Up Vector {~"=6iyj
The Up Vector is a vector in 3D space that is used to orient the projection plane a lR}|ez
for the irradiance map. The plane is defined so that the Up Vector is parallel to the JoYzC8/r
vertical side of the plane. The irradiance incident on the selected surface is fomkwN
projected onto this plane. When the map is displayed, the up vector will point 9maw+ c!~
toward the top of the screen.
