站长说的很对,补充一下: <{NYD.
Normal Vector FSU%?PxO
The Normal Vector is a vector in 3D space that is used to orient the projection ^/ DII`A
plane for the irradiance map. The plane is defined to be perpendicular to the +r-dr>&H@
Normal Vector, and the irradiance incident on the selected surface is projected v :+8U[x
onto this plane. When the map is displayed, the normal vector is pointing toward #NN"(I
you. xjK_zO*dLq
Up Vector si^4<$Nr%j
The Up Vector is a vector in 3D space that is used to orient the projection plane $\,BpZ
}3
for the irradiance map. The plane is defined so that the Up Vector is parallel to the &vFqe,Z
vertical side of the plane. The irradiance incident on the selected surface is (3N"oE.b]
projected onto this plane. When the map is displayed, the up vector will point 'Uko^R)(
toward the top of the screen.