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How to CGI...

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Amit ParekhHow to CGI...
by on Aug 18, 2013 at 5:54:39 pm

Sorry for the title being like it is, but basically, I want to know how to CGI properly. So I have this footage, shot within a game. I've used the inbuilt 3d camera tracker in AE and exported the camera to cinema 4d. WHen doing so, the camera actually winds downwards, underground instead of just following a straight path. But that doesn't matter. Then I exported the scene from the game and imported into cinema 4d and (best I could), keyframed it so it was as close as it could be to the scene. If there is a more accurate way to do this bit, I'd love to know, or I'll go ask the C4D guys.

Then after doing the 3d bit, I exported as a Quicktime movie with Alpha and imported it. Now I know I need to mask the sections of the original footage that are on top BUT how should I do it. Should I rotoscope or something. And is there an easier way of doing this all together? Because after importing the 3d Camera after being tracked, I think it was all downhill from there...

Sorry, so again, my question is, what is the best way to add additional 3D stuff onto pre-shot footage. So, unless I'm totally wrong about my terminology, how should I CGI?

If you have any more questions or anything, just ask. I'd love to know how to do this properly. Sorry for the wrong terminology and thank you in advance.

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Cassius MarquesRe: How to CGI...
by on Aug 19, 2013 at 8:33:10 pm

From what I understood you're having a hard time masking things out...

well, there are several ways and hardly there is a "best way". It will depend on how are the stuff that are/should be clipping your CGI.

So i'll try to give some examples and maybe get you thinking possibilities. If you have a wall/box/light post or anything else thats easily modelled I would recreate them and position them in the 3d scene as well, and use them as a matte there.

If you have trees that are the only green thing in the footage. Try to use the color to mask it out.

And when all else fails, you'll either rotoscope as you probably noticed or you can try a few masks (never use a single one, go for multi masks for each moving/perpendicular shape in the object)

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Amit ParekhRe: How to CGI...
by on Aug 19, 2013 at 10:07:29 pm

I've literally exported the world from the game. So the recreating bits, i understand. I think the main one is when it comes to masking. I'm not sure whether I should rotoscope or use masks. Look at the image and you'll be able to see what the footage basically looks like.

While everything outside the path changes, nothing really enters it, apart from the odd thing. So should I rotoscope or not?

And when it comes to 3d camera tracking, what would be the best way or doing it? Using something like mocha, or Bonjou or just the standard AE 3d tracker. I'd heard good things about all 3 and have no idea which.

Also, what did you mean when you said, "and use them as a matte there.".


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