站长说的很对，补充一下： GrF4*I` q
Normal Vector }n)0}U5;0
The Normal Vector is a vector in 3D space that is used to orient the projection &X4anH>O
plane for the irradiance map. The plane is defined to be perpendicular to the 2H%9l@}u
Normal Vector, and the irradiance incident on the selected surface is projected Ir;JYY!0?
onto this plane. When the map is displayed, the normal vector is pointing toward ^}
{r@F
you. IIk_! VzT
Up Vector s .M39W?
The Up Vector is a vector in 3D space that is used to orient the projection plane +!).'
for the irradiance map. The plane is defined so that the Up Vector is parallel to the A}fm).W p@
vertical side of the plane. The irradiance incident on the selected surface is SQMl5d1d:
projected onto this plane. When the map is displayed, the up vector will point txEN7!
toward the top of the screen.
