Motion Control Process
Published : 8th December 2004
>I'm planning to make a short in which I need to do a camera movement, a dolly back, while objects in the frame (furniture, people, even sources of light) disappear. I know motion control would be a good but very expensive solution. I'd like to know where I can search to learn about this technique and if anyone can imagine an alternate solution from this shooting.
>Sebastien Lemaistre wrote :
>I know motion control would be a good but very expensive solution.
>Define "very expensive."
>The simple fact is that the shot you described can only be done one of 2 ways: using live action with motion control or using CGI.
>Take your pick.
IATSE Local 600
>I'll offer another solution in addition to Michael's suggestions
>If it's a straight dolly back, you could time the dolly move with something like a metronome and marks on the floor and pace the shot so that each take is close to being the same. You should probably shoot the objects that are to disappear on blue screen, because you will probably have to move them around a little bit to compensate for their slip against the background and floor, since you will never match the moves exactly. This might work.
>But, as Michael points out, what's "very expensive"? The process I describe is cheap to shoot, but will involve many hours in compositing and repositioning. CGI is an expense unto itself that I can't begin to describe. Motion control passes could likely be assembled with simple split-screens and/or dissolves.
>Which one is really the most expensive???
Gear+Rose Motion Control
>>I'd like to know where I can search to learn about this technique and if >anyone can imagine an alternate solution from this shooting.
Here's one approach.. If you are doing a simple dolly back you might be able to achieve this effect without a motion control rig. The camera must be locked off so that it doesn't tilt or pan (and the shot must be designed so that you don't need to tilt, and this could be a drawback).
>The only movement can be the dolly moving the camera. It should be a real dolly, one that has some weight. Extra caution should be taken with people walking around the tracks- this area should be off limits. Just do multiple passes and remove the items from the set for each pass in the order in which you want them removed in the final shot. Then, blend together in post.
>I think that if your dolly grip has a fairly steady hand, you could get away with this with some speed matching in post.
Director of Photography
class="style7">>The simple fact is that the shot you described can only be done one of 2 >ways: using live action with motion control or using CGI.
>What about stop-motion? Objects could easily be moved in and out of shot. Use a geared head and mark the dolly track for a smoother move. Keeping the human talent stable and smooth would be the biggest problem, but you could spin it into a low budget stylised jittery look.
>Thanks for your reply.
>I did yesterday some tests using almost the same technique you described and it worked pretty good. By dividing the dolly movement in as many fractions as objects disappearing I could even manage to do some panning and tilts between each camera cut. The dolly grip made a really precious work by maintaining in each fraction the same speed. We made the test in video and edited it in final cut pro. The cuts are imperceptible.
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