In fxguideTV ep #131 John Knoll talked about having to wing it with a Canon 5d when shooting lighting info and reflections for a CG car. He mentioned attaching the 5d to the target vehicle in several different places (roof, hood, windows) in order to capture footage for lighting and reflections.

Was wondering how that process works...are those 5d movies then being mapped into hold-out mattes for the reflections in compositing? Also, are those movies actually used (in theory, whether he did or not) for the image based lighting itself, or simply as reference for the lighting setup? (He mentioned shooting straight up gave him pretty close to a 180 degree dome.)

Hope my question was clear, and thanks for any insight.