I noticed strange issues with double sided objects, in my case, fences. It's related to normal & specular maps and night illumination. If surface normal is facing in the same direction as light source then normal maps and specular maps effect aren't visible and plane doesn't react on night lighting. And if surface normal is directed opposite to the light source then specular & normal maps effects are visible from both sides and plane react on night lighting on both sides. link_a1 link_b1 ----- link_a2 link_a3 link_a4 link_b2
