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Using mattes/rotoscoping in after effects/twixtor?

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Christopher Hana
Using mattes/rotoscoping in after effects/twixtor?
on Sep 15, 2011 at 8:30:09 am

Alright so for the past 3 days I've been searching all through the net on the process of creating mattes in twixtor. My target footage is that of my friend jumping out of a ramp into the sky doing a barspin. Now the target slowmo time is almost entirely of him in the air against a blue sky backround, at the height of his jump. So I have pretty good footage to track i assume.

I've gone through alternating my main BG sensitivity with keyframes, and using some of the tracking points that comes with twixtor natively. Now even so with that, I still get an undesirable amount of ghosting/goopiness as soon as the wheel spins around, since the entire wheels crosses itself for a frame or 2. I'm trying to get this shot as completely clean as I possibly can, so the extra work of rotoscoping is no problem for me.


My understanding of the process so far is that-

1.After twiddling with my twixtor settings, I need to make a new "Solid" layer in the same comp, Or I can alternatively place twixtor in the solid as well and then mess with my settings.

2. I need to turn off twixtor or change the display to source so that I can see my video normally, without any "twixtoring" going on.

3. In the new solid I need to rotoscope the bmx for however many frames I'd like the twixtor effect to be on. Let's say a good 50 frames.

4. turn twixtor back on, and in the FG1 settings under FG1 Matte, I choose my solid with the rotoscoping in it.

5. in the FG1 matte chan change it to alpha.

6. render and we're done?


Now I'm thinking well that was easy right?
I go to render out some test footage and it looks like all I did what rotoscope his bmx wheel in midair and left it there.

Did I go wrong anywhere? and If I did, what did I need to do exactly?
also, is this even how you use the mattes? if not, please explain.

I've already gone through a barrage of threads on here, and have gone through the manual that comes with twixtor as well.
But I would really like a Step for step answer. Like imagine If a murderous clown hit me with a rocket chainsaw and I was taking steps quite small. Due to the massive gaping would an such. Those kind of small steps.

Right now I'm using after effects CS5.5
If you'd like to see my project as well here is my footage http://www.mediafire.com/?trs863dylpdhtbe
And my after effects scene http://www.mediafire.com/?0fbd89iuzv4w5mv

I'm posting this at nearly 3:30 am so I'm some what desperate, so any help would be much appreciated!

This is where I put some sort of witty sig, right?


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Peter Litwinowicz
Re: Using mattes/rotoscoping in after effects/twixtor?
on Sep 15, 2011 at 3:26:06 pm

[Christopher Hana] "In the new solid I need to rotoscope the bmx for however many frames I'd like the twixtor effect to be on. Let's say a good 50 frames."

Hey there, I haven't looked at your project or footage yet, but I see a problem with this already. First. the roto matte should not be on the layer where twixtor is applied. Mattes on a layer are applied AFTER the effect, so Twixtor will never see the matte unfortunately (this is an issue with AE, not Twixtor). You should do your roto on another layer. and then you'll want Twixtor to point to that second layer as FG1 (and not to itself!). In order not to see that second layer, you can eventually make it invisible, because internally Twixtor can still get the new roto-ed alpha.

When you ask Twixtor to display FG1, does it show the footage masked by the matte? I'm presuming not.

But even that's not the proper answer.

Another gotcha: There is a "bug" (they call it a feature) in AE that plugins can't get another layer with the masks applied, so even after you've rotoed a matte in a another layer, Twixtor will see that other layer as a frame with all white alpha.

As a first step, precompose your solid with the matte, then include that composition into the comp with Twixtor and point FG1 parameter in Twixtor to the precomp. This means you'll need to roto in one comp, and Twixtor in another.

Pete Litwinowicz
RE:VIsion Effects



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Christopher Hana
Re: Using mattes/rotoscoping in after effects/twixtor?
on Sep 30, 2011 at 6:35:01 am

Sorry for not responding for a while >.> I went on vacation for almost two weeks.

Anyways, after following your instructions of rotoscoping in another comp and "precomposing" it, I've come across a few "problems".
after adding the pre-comp to the output comp that twixtor is in, twixtor seems to not add the alpha information that is given. It doesn't change in anyway whatsoever. Even if I change the FG1 matte to none, or the "precomped" alpha layer it still doesn't change.

So I'm thinking to myself, "Well if it's not being picked up but the layer is a good roto(I think) then it must have something to do with the layer in the timeline in conjunction to the time placement of the twixtor layer.
So What I did was tick the twixtor layer to show only the source footage, move my "precomped" alpha layer in the timeline to match up with the source footage. Now I set the twixtor layer to show the "twixtored output" so we can see if it's changed at all.

after doing that I finally get something different happening, but now it looks like this(A picture is a thousand words, right?).
I run a dual screen by the way.

So as you can see, it looks worse than a professional boxers face after a 13 round fight. Now your advice did help me to initiate the matte FG1 to be used in in twixtor, but now I'm completely stumped on how to fix this "issue".

Of course if you'd like to check my project - http://www.mediafire.com/?1dz1bcmqbypqdtg
And the footage - http://www.mediafire.com/?is37vuxs8vt5ur4

This is where I put some sort of witty sig, right?


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Pierre Jasmin
Re: Using mattes/rotoscoping in after effects/twixtor?
on Oct 4, 2011 at 6:37:09 pm

I only see the output movie
not MVI_2807.mov which is what I would need to look at yout project

Pierre
RE:Vision Effects



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Christopher Hana
Re: Using mattes/rotoscoping in after effects/twixtor?
on Oct 7, 2011 at 6:31:19 am

Well the original footage is around 12 minutes in length and 2 gigabytes in size. o.o so uploading it is a bit difficult.
So I've gone and trimmed down the original sized footage in premiere and uploaded it as an mov.


http://www.mediafire.com/?k5suykmlrgqegz1

This is where I put some sort of witty sig, right?


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