站长说的很对，补充一下： -,{-bi
Normal Vector CZt \JW+"
The Normal Vector is a vector in 3D space that is used to orient the projection m7GR[MR
plane for the irradiance map. The plane is defined to be perpendicular to the JS>Gd/Jd
Normal Vector, and the irradiance incident on the selected surface is projected +@K09ge
onto this plane. When the map is displayed, the normal vector is pointing toward &gE 75B
you. #I3$3^0i#
Up Vector <P;}unq.kw
The Up Vector is a vector in 3D space that is used to orient the projection plane BEgV^\u
for the irradiance map. The plane is defined so that the Up Vector is parallel to the aCxE5$~$
vertical side of the plane. The irradiance incident on the selected surface is (%:>T Q(
projected onto this plane. When the map is displayed, the up vector will point T,OwM\`.X{
toward the top of the screen.
