February 08, 2012, 08:37:00 pm
The polygons in this room were single-sided in the 3D modelling application. Just create a new room with double-sided polygons in your 3D modelling appliation, and import it in Lumion.
You currently can't force materials to appear double-sided in Lumion (although the Glass material in 2.1.1 now includes a Double-sided setting).