In the making of they show how they were using front projection for the SFX, however I am at a loss to understand how this would actually work. I understand they are combining live action with a still plate in camera, but what I don't get is how all the negative space that is to be replaced by the plate image does so without affecting the foreground image. Today, they would use blue/green screen for these effects and do them in post production. They shoot the models, and anything blue is replaced by the new background. I could also see rear projection being used, since they are photographing a foreground object against a static background, so what you see would be what you'd get. For Star Wars, they had an elaborate optical process for the space scenes, creating mattes for each ship and burning them into the underlying composite scenes. This is all done after the fact. For front projection, how do they avoid getting the background image mixed in with the foreground? Does anyone have a pointer to a web site that explains this in detail? Curious minds want to know!