站长说的很对，补充一下： |2<y
Normal Vector Y~E
8z
The Normal Vector is a vector in 3D space that is used to orient the projection J,iS<lV_
plane for the irradiance map. The plane is defined to be perpendicular to the tx` Z?K[
Normal Vector, and the irradiance incident on the selected surface is projected Y -yozt
onto this plane. When the map is displayed, the normal vector is pointing toward {KQ-QKxxS
you. m*bTELb
Up Vector (G1KMy
The Up Vector is a vector in 3D space that is used to orient the projection plane dC'8orFG+
for the irradiance map. The plane is defined so that the Up Vector is parallel to the EM2=g9y
vertical side of the plane. The irradiance incident on the selected surface is k^VL{z:EWB
projected onto this plane. When the map is displayed, the up vector will point >H r&F
nh+
toward the top of the screen.
