The brown lines that you can see on the layout are fire doors - big heavy wooden doors with three small square glass panels in each one. The Lumedyne flash unit with a Pocket Wizard receiver on was placed outside the door and the door was closed. The subject was lit entirely by the hard, un-modified flash coming through those three glass panels. Lining up exactly where the light will fall is very easy - if the subject can see the flash head, then it can see them. After that it is just a question of shooting a couple of frames and judging on the camera's LCD screen where the light is falling and then raising, lowering or moving the flash accordingly.
In this case the flash is about ten degrees above the subject's eye line and he is looking almost directly at it. This allowed me to get the nice hard shadow behind his head and still have a reasnably flattering light on his face. I also tried to do a few rames where the ambient light in the corridor (a very warm golden tungsten) was making the shadows softer but I much preffered this hard treatment.