I've started lighting an exterior scene, and I'm pretty much happy with that. I will present images for a lighting and texturing competition (no real prizes, only badges or icons on the forum.. and then there's the kick in the butt for those who use 3Ds Max to take a peak over the fence - the grass is greener on this side, eh?

) and in one of the shots I'm placing the camera so that you can get a peak inside one of the buildings. See screenshot provided.
Even though I have Physky activated to light the exterior scene, the interior is dark and dull. I've thought about luma planes, but I'm struggling a little bit. Even though I check the "Unseen by camera", it still renders the plane itself. Any way to fix that, or are there other ways to make it look good, if not better ?