Its really cool. The effect of a portal door window would probably help you assemble the painting as a level. I think orthographic mode, and then fading into a perspective camera would be pretty awesome effect. As if u were staring at a wall in ortho and blinked then it became perspective. A long time ago i was at a wax museum and they had a orthographic projection box with the eyehole next to a wax action display and when u looked through it was like a photo of the painting.