OK, so what is this?
This is a proof-of-concept render using the camera obscura technique. The scene is a closed room except for a very small hole in the back wall. Light rays travel in a straight line but because the hole is so small it will actually project an upside-down image on the wall. Wikipedia article.
The cool thing is that you can actually do this in real life.
This render was just a test to see if LuxRender could do it and it worked nicely. Idea originally by user pnn32 on DeviantArt.
Rendering: LuxRender 1.51
Modeling: Blender 2.75
Hdr image from openfootage.net