[Stuart Elith]

From what I can understand, a track matte is indeed what you want.

A track matte will use the pixels on the layer as transparency for the layer below (using alpha or luminance).
So if you have the particle streaks and use that as a track matte for something else, the particles will not be shown at ALL but will be a mask through which the other layer shows.

Not sure what you may be doing “wrong”…

[Stuart Elith]

You don’t actually need to apply the tracking data to a null (though you can if you want). I prefer not to, as it keeps one less layer in the timeline and I don’t delete my original tracking markers after I use them, so i can just access them in the original footage.

So what I do is this :

1. Track the feature.
2. On the first frame, do your cloning. Make sure the clone settings are set to Constant duration rather than just a single frame. You will need to think about where to choose your clone point so that it will be consistent throughout the shot and won’t reveal the stuff you’re trying to hide (if you don’t get what I mean, it will make sense once you try it! It may work, or may require tweaking, but that’s ok too).

3. Add an expression to the Position of the clone stroke (in the timeline, it will look something like Effects > Paint > Clone 1 > Transform : Clone 1 > Position. You need to pickwhip this to the Motion Tracker track point’s Feature Center.

And that’s all!
If it isn’t perfect, you can adjust the Clone Position of the stroke (in the Stroke Options), which is great as you can then reposition it and see the results… you could even keyframe it if there is just one little bit that goes wrong.

[Stuart Elith]

If there is any way you can get the footage on before you shoot, it will always give you a better result, because it’s REAL.

Otherwise, there is a thread dealing with exactly the same issue from not too long ago, probably in the last month. Try a few searches here at the Cow and you might be able to find it, there was some good advice there.

[Stuart Elith]

Another option to look into if you aren’t going to go the Mocha route is the TrackerViz script (which you can google). It allows you to do a few tracks and then average them, so that the little jitters and variations from the track get evened out.

[Stuart Elith]

So I think what you’re asking is to use the particles as a mask that tells which area of the title to appear?

If so, ready about track mattes in the manual, they will help you. It uses a layer as a mask for another layer 🙂

[Stuart Elith]

You could have a very hard time with this. Fully removing a background can be very difficult.

One advantage you may have here is that there is no noise in gaming, so you might look into Difference Matte where you basically remove everything that stays the same throughout the video. But if your background is moving, this won’t really work.

[Stuart Elith]

Michael, it seems there isn’t much out there on it, as you’ve found through Google.

As for the procedure, I don’t entirely understand it either. I only use it occasionally, and as long as I follow the procedure I have learnt, it works, and that’s good enough 🙂 There aren’t many variables as far as I can see, so for any situation I can conceive of, it is fine.

But here’s what I have tried to nut out :

The rotation * -1 is basically just inverting the rotation values that the stabilising put in. just like adding a negative in front of a Scale value on footage will flip it.

Swapping the position and anchor points :

Well, on the original footage, the position value isn’t actually changing, it’s the anchor point sliding that moves it. If you pickwhipped the anchor point to anchor point, it wouldn’t be resetting the anchor point to the original spot, it would be copying the same movement I guess. You can’t just do anchorPoint * -1 either, or it will be giving values like -900, -500, which will throw it off the stage.

Now, anchor point and position behave in opposite ways – increasing the position value for X will move it to the right, and increasing the anchorPoint X will move it to the left. Try it… put anything in a comp, look at the position and AP values (which will both be half of the comp width/height) and then add 5 to each… the result will cancel each other out.

So this is all you’re doing by pickwhipping them to each other – the position value takes on the anchorPoint values from the precomp, effectively cancelling them out. And the anchor point taking on the position values – well… i’m not sure if this is actually needed, as it doesn’t change throughout the stabilization. Perhaps in some cases, if the 2 comps aren’t the same size, it might matter, not sure.

Explaining that has helped me work it out in my own head, so that’s cool 🙂 hope it helps.

[Stuart Elith]

OK, well i have realised what *I* did wrong, hopefully it helps you too…
The inner comp (with the stabilization) needs to be scaled up so that the footage has plenty of room to move without getting cropped at all. Then, when it gets re-stabilized, it worked for me, even with rotation.

[Stuart Elith]

For some reason i’m now having trouble doing this too, even without the rotation!
I did a quick setup just to test what you had done (which is how I remembered to do it as well) and i can’t get it to work, yet I have another project using the same expressions that de-stabilized well!

Hmm, more investigation needed 🙂 We must have forgotten a step.

[Stuart Elith]

Ok, you have me baffled. The first way, splitting the clip then applying the effect, should NOT apply it to both clips. If you select the other clip, does Keylight show up in the effects panel (i.e is it ACTUALLY being applied to both)?

Tell me, you aren’t looking in the LAYER window when you say it’s being applied to the whole clip? You always need to check your results in the comp window.