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View Full Version : Shooting for 3D match VFX: cavity inside a body: markers?



jeric_synergy
11-30-2012, 12:17 PM
So, the idea of the VFX is to have a compartment INSIDE the talent's body, like a refrigerator.

A rendered door+compartment must be camera matched to the talent's position & rotation.

My question is: what kind of markers should be added to the talent's clothing to assist in the match?

If the rendered items were exterior to the body this would be conceptually simple: does it make any difference that instead this is a void inside the body?
fwiw, the compartment is rather small (for a refrigerator), about 6"x6".


Thanks!!! (examples gratefully welcomed)

Areyos Alektor
12-04-2012, 07:03 PM
It's not a camera tracking but object tracking. Guides for whatever type of project should be playing on the contrast and visibility, as well that place them in space to help the depth and the parallax.

For tests you can go get media here:

http://www.hollywoodcamerawork.us/trackingplates.html

sami
12-05-2012, 12:18 PM
Also remember to not put markers on deformable objects like clothing or someone's jiggly tummy. Instead try a very well affixed armor plate or stiff cardboard in the right place. Object tracking on the head is easy because generally the skull doesn't deform (when it is used properly that is ;) )


Edit: to clarify I mean put the markers on the stiff cardboard etc so they don't move, ideally 6 or 7 marker is good and size is dependent on distance to camera and its motion.

sami
12-05-2012, 12:21 PM
Also void inside doesn't make much of a difference, you still have masking issues if an arm occludes it, but maybe you'll also need to track the arm that occludes the void, depending on if the fridge inside is self lit or gets lit from the outside, as realistically some kind of shadow would appear in the cavity if something passes between it and the light source - so that sells the effect too.

sami
12-05-2012, 12:28 PM
Here's an awesome object tracking example, but they were doing animal heads on tracked human heads. Humans were wearing LED lighted stiff helmets as markers. They needed the lights because of the dark environments they were filming in. Eventually all cameras will have IR depth sensing like the Kinect built in and we'll never need to deal with this again ;-)


The Animal Within example:
http://forums.cgsociety.org/showthread.php?t=561565

EDIT: Just noticed the links are broken in that forum post since I've seen it a while ago but here is the tv ad: http://www.youtube.com/watch?v=emWSUUGo17w

Sorry can't find the behind the scenes helmet marker videos when they were shooting it. It might be on vimeo though.