站长说的很对,补充一下: ^b=] =w
Normal Vector FT'_{e!M
The Normal Vector is a vector in 3D space that is used to orient the projection :|/bEP]p/
plane for the irradiance map. The plane is defined to be perpendicular to the Cw1Jl5OVZ
Normal Vector, and the irradiance incident on the selected surface is projected c(jF^
0~
onto this plane. When the map is displayed, the normal vector is pointing toward *gRg--PY%
you. Erz{{kf]1V
Up Vector &>kklP
The Up Vector is a vector in 3D space that is used to orient the projection plane ]37k\O?vd
for the irradiance map. The plane is defined so that the Up Vector is parallel to the W!B4~L
vertical side of the plane. The irradiance incident on the selected surface is j.O7-t%C
projected onto this plane. When the map is displayed, the up vector will point
5|2v6W!e
toward the top of the screen.