站长说的很对,补充一下: .BuXg<`
Normal Vector WPPz/c|j
The Normal Vector is a vector in 3D space that is used to orient the projection sG!SSRL@
plane for the irradiance map. The plane is defined to be perpendicular to the c*sK| U7)
Normal Vector, and the irradiance incident on the selected surface is projected *G"L]Nq#
onto this plane. When the map is displayed, the normal vector is pointing toward mI_ ?hl?Pv
you. #T &z`
Up Vector 'Y Bz?l9
The Up Vector is a vector in 3D space that is used to orient the projection plane h&|q>M3
for the irradiance map. The plane is defined so that the Up Vector is parallel to the j-e/nZR@
vertical side of the plane. The irradiance incident on the selected surface is Z/n\Ak sE
projected onto this plane. When the map is displayed, the up vector will point r+r-[z D(
toward the top of the screen.