set as an alpha inverted matte?

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Old 12 December 2013   #1
set as an alpha inverted matte?

I'm reading a tutorial off "3D world" magazine. it has a tutorial for after effects CC and cineware. At one point it asks to set a precomposed layer as "an alpha inverted matte". How do I do that?
Old 01 January 2014   #2
Choosing layer-trackmatte-alpha inverted matte will transfer
inverted alpha from the above layer to the currently selected.
Old 01 January 2014   #3
Read about it here:

Next time though, try googling for half a minute.
Old 01 January 2014   #4
Originally Posted by catche: Read about it here:

Next time though, try googling for half a minute.

Was done. Which is why I came here.
Old 01 January 2014   #5

Hope you got it working.
Old 01 January 2014   #6
Originally Posted by catche: Alright

Hope you got it working.

Thanks, I did get it working.
Old 01 January 2014   #7
Looks good. What did you use for tracking? And did you use any specific tutorials to learn it? I tried tracking once, but it came out horribly: Any tips?
Old 01 January 2014   #8
There are a few things I think you could do to improve your results there, catche. First, physically stabilizing your camera would be a good idea. Even something as simple as keeping it attached to a tripod while you move it around gives the camera more mass and reduces the shake your hands impart to it. Of course, you still have to move pretty steadily; even a proper steadicam can only do so much. Reducing the shake reduces motion blur, which increases the amount of detail your tracker can use to generate points.

Second, it looks like you had autofocus on. Not only did that cause sudden unwanted blurring, it also rapidly altered the focal length of your lens. Not a lot, maybe, but possibly enough to disrupt the track. In addition, that sudden loss of focus means that your tracker probably lost quite a few of its tracking points. It may have picked them up again after the refocus, but unless you told it which of the new points matched old ones, the tracker had no way to correlate the new surface it was seeing with the old one.

Third, it looks like when the tracker lost its stability, there was little in the way of parallax for it to use to determine the nature of the physical geometry it was looking at. You were looking almost straight down, with no lateral motion to give it perspective clues. Since most of the tracking points were also likely new, there was no way for the tracker to know that the points it was looking at on that carpet were supposed to be in the same points it was looking at earlier. Thus, the model lost its apparent contact with the floor.

The obvious solution is a reshoot to improve the quality of your source footage. Failing that, you can use monitored tracking points (User Tracks in PFTrack. Not sure what they're called in other tracking programs) to try to establish a continuous motion source across the defocused area. The key is to make some data that crosses that point and remains stable afterward. That should make sure that the model stays put. If necessary, you can manually keyframe those points, or even manually keyframe the camera itself in order to smooth it out across the uncertain part of the footage.

I wish I could say that you'll never see footage that bad in production, but that's just not true. There eventually comes a time when you just have to do the tedious work of manually keyframing a camera, or to accept a compromise solution that maybe doesn't work perfectly but is good enough for the problem at hand.
Bryan Ray
Old 01 January 2014   #9
Thanks a lot for the informative response!

I guess a reshoot would be the best. The goal of the project however, was to make it look not like a proper film, but rather more like a person filming his/her pet that's asking to go outside (the plan was to animate the character). But as you are saying it's probably a difficult shot to track, at least too difficult for me as a first ever.
Old 01 January 2014   #10
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