站长说的很对,补充一下: htM5Nm[g
Normal Vector B'yN &3
The Normal Vector is a vector in 3D space that is used to orient the projection OMKEn!Wq
plane for the irradiance map. The plane is defined to be perpendicular to the UY}lJHp0
Normal Vector, and the irradiance incident on the selected surface is projected hJFQ/(
onto this plane. When the map is displayed, the normal vector is pointing toward O(&EnNm[2
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Up Vector g^B6NF
The Up Vector is a vector in 3D space that is used to orient the projection plane 71K6] ~<
for the irradiance map. The plane is defined so that the Up Vector is parallel to the $|(roC(
vertical side of the plane. The irradiance incident on the selected surface is .]r[0U
projected onto this plane. When the map is displayed, the up vector will point {zVJlJKxs
toward the top of the screen.