站长说的很对,补充一下: #3
E"Ame
Normal Vector z{OL+-OY
The Normal Vector is a vector in 3D space that is used to orient the projection w~Q\:<x&~Z
plane for the irradiance map. The plane is defined to be perpendicular to the wp1O*)/q
Normal Vector, and the irradiance incident on the selected surface is projected QDY uJ&!h
onto this plane. When the map is displayed, the normal vector is pointing toward j;}-x1R
you. aMe&4Q
Up Vector wry`2_c
The Up Vector is a vector in 3D space that is used to orient the projection plane 9U<WR*H
for the irradiance map. The plane is defined so that the Up Vector is parallel to the ,X_3#!y
vertical side of the plane. The irradiance incident on the selected surface is DDmC3
projected onto this plane. When the map is displayed, the up vector will point KB~[nZs7
toward the top of the screen.