站长说的很对,补充一下: Ku$:.
Normal Vector Qa>t$`o`
The Normal Vector is a vector in 3D space that is used to orient the projection |$
plane for the irradiance map. The plane is defined to be perpendicular to the ~)vq0]MRg
Normal Vector, and the irradiance incident on the selected surface is projected Klrd|;C
onto this plane. When the map is displayed, the normal vector is pointing toward (J}tCqP
you. F}MjZZj(U=
Up Vector ^Q,-4\ec
The Up Vector is a vector in 3D space that is used to orient the projection plane %1h%#/#[
for the irradiance map. The plane is defined so that the Up Vector is parallel to the J@$KF GUs
vertical side of the plane. The irradiance incident on the selected surface is As"%
u
projected onto this plane. When the map is displayed, the up vector will point &Zy%Zz
toward the top of the screen.