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View Full Version : Suggestions to solve a VFX problem


quinton84
03-20-2009, 05:55 PM
Hi guys,

This is the first time I'm posting something up here. I'm not quite sure if this is the correct place to ask my quuestions. Please forgive me if it's out of topic, but I need some help and advise on a vfx shot that has wasted many man hours of my time.

I'm working on a visual effects shot for my grad module that I can't quite get my mind to wrap around in the easiest way possible.

The effect is simply a girl lifting up a car.

here's a real quick animatic of the shot I'm trying to achieve.
http://www.youtube.com/watch?v=9amYM69AWYk&feature=channel_page

Due to the camera's movement, I'm having some problems.

Previously I have shot a live-action plate of a girl lifting up a blue car prop but there has been some problems.
http://www.youtube.com/watch?v=oOZdqQVqggs&feature=channel_page (around the 46s mark, the shot is labeled 406)

1. The car prop and the girl were both moving in the shot, resulting in an unusable camera motion track with both match-mover or maya live.
2. Manually matchmoving the camera's movement was too difficult for me, as there was factor's of tilt, zoom, pan. I couldn't get it to match well.

Basically I'll need to composite the car into the shot in such a way that it seems the girl is lifting it up. On top of that because of the way the camera is moving, I need to match the movement of the camera with the maya cam. and finally, as the camera get's behind the girl, the CG car must appear behind the girl.

I was thinking of just reshooting a wider-angled scene to capture more "static" objects to give me a good track in match mover pro.

However, I can't think of how to resolve the problem of how to composite the girl in front of the car at the latter parts as the camera moves behind her(placing the girl between the camera and the car). I had tot to shoot the girl lifting the car in blue screen, but I realise that the camera movement will not match that of the live-action background plate.

I hope I was clear about what difficulties I'm facing and what effect I want to achieve.

Any suggestions from seasoned vfx artists? Many thanks in advance!!

Cheers,
Nelson

quinton84
03-24-2009, 07:48 AM
any suggestions anyone?

lazzhar
03-24-2009, 09:07 AM
I would just go back to match moving. Try to mask out moving elements and focus on what's fixed. Once you solve the camera, the rest should be straightforward.
Good luck.

Makaze
03-26-2009, 12:27 AM
Yeah. Try matchmoving the shot again. It should be possible. You can always tweak the contrast and check the different color channels in matchmover to see which one will give you the best result.

Regarding putting the girl in front of the car. You can easily rotoscope that part and create a matte for her. Then premuliply her with the matte in a compositing program of your choice (After Effects, Shake, Nuke etc). And put her in front.

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03-26-2009, 12:27 AM
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