Greenscreening a painting
by RubyHotWax
on
Jun 26, 2007 at 1:15:52 am
I have shot a scene in a Gallery of 2 people looking at a painting using a framed greenscreen painting that I now want to replace with a composed photoshop still. I've added the Keylighting effect and am happy with the result. However, the replaced painting is not aligned with the painting's frame and it moves around during the course of the scene. The scene contains dolly movements. How do I get the 2 items to be aligned?
Re: Greenscreening a painting by Darby Edelen on Jun 26, 2007 at 2:08:39 am
Welcome to the wonderful world of motion tracking! =)
You might be able to get away with a corner pin track using AE Pro's standard Motion Tracker, but if your camera move involves any moves more complicated than a simple push or dolly then you might need to use a 3D tracker such as Syntheyes (there are several others as well).
Darby Edelen DVD Menu Artist Left Coast Digital Aptos, CA
Re: Greenscreening a painting by epontius on Jun 26, 2007 at 2:18:17 am
The corner pin in the motion tracker should probably do the trick as long as all four corners are visible...if during the dolly track your actor's body obstructs the corner you might need to massage the keyframes to correct it.
I did something similar a few years back with video of a couple on a couch watching a wall mounted plasma. The camera crabbed, panned and zoomed out of a shot where the plasma filled almost the entire screen to a shot of the couple on the couch. Corner pin worked pretty well with only some minor tweaks.
Re: Greenscreening a painting by RubyHotWax on Jun 28, 2007 at 2:44:21 am
Thank you so much epontius & Darby for pointing me in the right direction. Knowing that I needed to motion track using corner pins meant I was able to do further searching and I found some tutorials & guides (see yikesmikes' recent post for a list of tutes & guides: http://forums.creativecow.net/cgi-bin/new_read_thread.cgi?forumid=2&postid=... Sadly, through my reading and experimenting in AE, I've discovered that I had probably broken every rule during the shoot (actors block the corners of the painting, the camera tilted down so that some of the painting was off screen at times etc) and so am unable to motion track sucessfully throughout the entire shot. Well, at least the painting was well lit!
As an "emerging" freelance editor, I can't quite quite afford this software, so I am devising a workaround where I will zoom in to focus on the actors until they move away from the painting (excluding the painting from the shot), when I can do a successful corner track as the frame is wide then with all 4 corners unobscured. There will be a few seconds where part of the painting's frame is in shot as the actors get up - I may be able to use a lens blur to place the background out of focus at this point.
Thanks once again for your advice - all other suggestions gratefully received!
