站长说的很对,补充一下: q2S!m6 !
Normal Vector \&\_>X.,
The Normal Vector is a vector in 3D space that is used to orient the projection 0U~;%N+lv
plane for the irradiance map. The plane is defined to be perpendicular to the d Y:|Ef|v(
Normal Vector, and the irradiance incident on the selected surface is projected 56bud3CVs
onto this plane. When the map is displayed, the normal vector is pointing toward {XDY:`vZ}
you. {w |dM#
Up Vector hr_9;,EPh
The Up Vector is a vector in 3D space that is used to orient the projection plane :~ZqB\>i
for the irradiance map. The plane is defined so that the Up Vector is parallel to the *gM,x4 Y
vertical side of the plane. The irradiance incident on the selected surface is j]!7B HC
projected onto this plane. When the map is displayed, the up vector will point 't0+:o">:
toward the top of the screen.