It had occurred to me dimly some time ago that "mapping" might be a new word for an old concept. Recently, I was asked to speak on a panel discussion about projection design held at the Theater Resources Unlimited in New York City. I was asked by a member of the audience about projection design and how the mapping on Newsies worked. I replied somewhat cryptically by saying "the same way it has always worked. You match the physical reality of the set and projector to the virtual reality on the playback side." Of course, that is easily said, but it does not really explain anything. In my defense, I did not mean to be mysterious about the subject—I had merely just realized the very thing I had uttered.
Richard Pilbrow told me how he had figured out how to make the projections on One Over The Eight work by using what he refers to as a "jig." He knew that in order for the projected image to appear on the surface as intended, the artwork had to be pre-distorted. That means distorted to compensate for the position (and lens) of the projector relative to the scenery and set. His jig (built by Richard Orbo), was a little set-up (well a 1/2"=1' scale model) with a camera set into a scale model of the set design. He took a picture of the projection surface in the model from the same spot he could have a projector rigged. He also tried to match the lenses between the projector and the camera. This way the camera would "see" the surface exactly as the projector would (if it was a camera).
To judge the amount and type of distortion, I imagine he put a grid with horizontal and vertical lines and possibly a circle on the surface of the "jig." The resulting camera picture could be used as a template to distort all the artwork. That was in 1961. In effect, he had mapped the imagery to the surface. The story is described in Richard's book entitled A Theatre Project.
I first learned about pre-distortion when I started dabbling with projection back in 2000. I was realizing a fake product launch at college with the aid of five Kodak carousel projectors. It had not occurred to me until then that there a crafty bit of work that projection professionals did to make the slides appear with the right angles and proportions of the original artwork on the projection surface. My slides certainly did not look as intended, because the projectors where hung high up in the ceiling and pointed down at about 30 degrees with a wide-angle lens. The projected images were some ugly trapezoid shapes which did not particularly aid the large text in the artwork, but at that time I was more concerned about triggering and fading the slides at the right time and in the right sequence. I asked the chap I had borrowed the projectors and dataton trax gear (which I used to control the projectors) from about the little artwork problem I has encountered and he just smiled and said; "well, you need to pre-distort the slides if you know you have to rig your projectors at funny angles and in strange places." That person was Dick Straker whom I met whilst helping out on a corporate event somewhere out by Heathrow airport.
Fast forward to 2004. Dick and I were entrusted by William Dudley to design a system that would show his artwork for The Woman in White as intended on all the revolving, moving and concave surfaces of the set he had designed. This required a whole new approach to mapping, particularly because the screens moved and the imagery was supposed to move with the physical pieces. To be continued.