View Full Version : Creating Selective motion blur

04 April 2007, 11:51 AM
Hi all, I've been asked to create one of those scenes where all the action except the central character is motion blurring. It's a fairly common effect. I'm just trying to think of different ways to accomplish it.

My original plan was to lock off the camera, shoot a clean background, shoot the central character and then roll for several minutes on people walking around in shot. I could then use the clean background and the central character to create a difference matte, apply RSMB to the shot of people moving around and then layer this outside the difference matte. I'm curious if this would work.

But it now appears that the client wants to shoot in public and I won't be able to get a clean background. They may also want to dolly in on the central character.

So I'm now wondering if I can shoot all the elements at once and apply motion blur to the whole thing. I might create a blurred garbage matte to stop my central character from blurring. But I'm hoping that because his motion is minimal he simply won't blur much.

Has anyone had any experience with this sort of thing. Or care to add some suggestions?

Any thoughts are appreciated.



04 April 2007, 12:45 AM
I did some things like this where we had a moving camera crash zoom on an actor and it had to time warp and blur. I ended up using a retime to slow everything down, then found if you stabilize the plate using the actor as the 'lock-off' point, then speed up the footage using Blend as the retime mode. Everything smears except the actor (as long as they don't move much)

may not help much for waht you are doing but it's an idea

04 April 2007, 02:42 PM
Thanks. Your idea to slow down and then speed up with blend may come in very handy. Am I right in thinking this would give you a sort of frame averaging?


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04 April 2007, 02:42 PM
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