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View Full Version : Compositing 3D renders onto live footage/images

KenMADE
02-15-2009, 04:59 AM
I am trying to complete a project, but I keep running into problems. Hopefully someone will know how to solve my dilemma:

Basically what I am trying to do is render out a single object in Maya and then composite the object onto a live photograph. This is something I could see myself using frequently if I could get it right. What I am working on now involves a 3D version of a gun arm (similar to a Samus Aran gun) and an image taken in real life. I am trying to render out the gun, bring it into photoshop, and composite it onto the live image to look like the person has the gun for an arm.

The problems I am running into include: rendering the image incorrectly in Maya so it isn't entirely compatible with Photoshop, trying to composite it in Photoshop but having it look too transparent or incorrect in other ways, and other small errors. If anyone has any advice involving 3D compositing onto live action I would very much like to hear it. Thanks!
leigh
02-15-2009, 01:34 PM
You should give some more information about your current process. What format are you rendering to from Maya?

The most straightforward method of doing this would be to render to a TIFF or Targa file, or another format that supports alpha channels. This will allow you to easily separate the rendered element from its rendered background.
djart73
02-15-2009, 04:55 PM
Hi KenMADE,

please take a look to these link´s...

http://www.uni-duesseldorf.de/URZ/hardware/parallel/local/softimage/Soft3D_html/tutorial/roto/default.htm

http://www.vassg.hu/kisauto_en.htm

http://www.cmivfx.com/Eat3D/Live_Action_and_CG/default.aspx

Maybe this helps you a little.

An Workflow could be,

take the picture in your viewport in Maya with the size of the picture,
move your gun arm to the desired position so it will fit to the person.
Look where the light comes from and position a few lights until the 3d arm matches the light and shadow from your footage.
Render it out with a fileformat that includes Alpha or use a Mattechannel.
I use often Quicktime PNG with alpha on.
If you now take the rendert arm into PS, it fits.
Then colorcorrect it and look how the DOF is.
You might blurr it a little to make it fit seamlessly.

Greets djart73/ before rasher73:-)
KenMADE
02-15-2009, 08:51 PM
Thanks leigh and djart73. I eventually tried a targa, but I wasn't exactly sure how to use the alpha channel. Once I get a chance to get back to my studio computer I will give it a shot and see if I can get it working. Thanks again!
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