站长说的很对，补充一下： T+z ZOI
Normal Vector CeoK@y=o
The Normal Vector is a vector in 3D space that is used to orient the projection 6+A<_r`#Q
plane for the irradiance map. The plane is defined to be perpendicular to the i2A>T/? {
Normal Vector, and the irradiance incident on the selected surface is projected "?hEGJ; m"
onto this plane. When the map is displayed, the normal vector is pointing toward &!vJ3:
you. xWD=",0+
Up Vector (Sr& Y1D
The Up Vector is a vector in 3D space that is used to orient the projection plane qi_[@da f?
for the irradiance map. The plane is defined so that the Up Vector is parallel to the ~xpU<Pd*
vertical side of the plane. The irradiance incident on the selected surface is 8P0XY
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projected onto this plane. When the map is displayed, the up vector will point 2j` x^
toward the top of the screen.
