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Dale Paquette
Stabilize Precomposed Layer
on Nov 4, 2009 at 11:45:54 am

I'm confused. I am trying to stabilize (pos and rot) some hand-held footage which isn't too bad to begin with. My plan is to
desaturate the footage and then use curves to create a very hicon version. This enables me to clearly spot good tracking points. I can only get this to work by outputting the footage as an avi, importing the avi and tracking it, and then cutting and pasting the keyframes. The result is about as good as it gets! But, this seems unnecessarily complicated. I have tried precomposing the layer with its effects and tracking that, but upon telling the tracker to stabilize, it reverts back to the original low contrast color version. What am I doing wrong?

Also, the original footage is HDV. Will I get better results if the footage is decompressed first (avi)?

Thanks, Dale


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Dave LaRonde
Re: Stabilize Precomposed Layer
on Nov 4, 2009 at 3:54:58 pm

Motion Tracking and Motion Stabilization both have various ways to pre-massage the tracking points you selct: you can track by luminance, RGB, you can pre-blur, etc. If you haven't tried them out yet, you should. You should also know that depending on the image on the footage, getting a good track often takes several attempts.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Roland R. Kahlenberg
Re: Stabilize Precomposed Layer
on Nov 4, 2009 at 4:17:33 pm

It's very strange that you can't track or stabilize a nested comp. Sorry but I think it's a case of user error. Have you tried open the nested comp in its Layer Panel and tehn opening up the Tracker Controls Panel, in that sequence. And evem then, from the Tracker Controls Panel, there is a drop-down menu to selct the source for the tracking/stabilization.

And creating a hi-con version for tracking is a good idea in certain cases cos it allows you to exclude information that you don't need while accentuating the ones that you do.

BTW, how did you manage with the averaging of your tracks?

Cheers
RoRK

Sell your AEPs with broadcastGEMs' DVD series of templates. Click here for more


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 4, 2009 at 5:36:30 pm

Thanks for the response. Is it operator error? I'd bet on it!! That said, I'll try your suggestion later today.

The hicon version seems to allow for better separation of highly luminescent points allowing me to make a much smaller feature box and search box thus speeding up the whole process. I'll be busy working this some more soon as I fix my precompose problem.

So far, I have made most of the averaging part work, but seem to be having some difficulty with the expression. I'll keep at it till I get it.


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Roland R. Kahlenberg
Re: Stabilize Precomposed Layer
on Nov 5, 2009 at 6:10:12 am

[Dale Paquette] "The hicon version seems to allow for better separation of highly luminescent points allowing me to make a much smaller feature box and search box thus speeding up the whole"

That's true but there are many other reasons to create a hi-con version for tracking. If you had a point to track and that point has an object with a similar color close to it then the tracker is likely going to have issues. Changing either of the colors so that they better match each other gives you a bigger feature region to track and hence less issues for the tracker. Strictly speaking, this isn't a case of creating a hi-con version but the process is to create a versino that is more tracker friendly.

As for the averaging, perhaps you can be specific with your issues if you haven't solved that yet.

Cheers
RoRK



Sell your AEPs with broadcastGEMs' DVD series of templates. Click here for more


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 5, 2009 at 12:01:13 pm

RoRK, I understand.

As for averaging, I imported footage and duplicated twice (3 copies). One I call the master and the others stabilize 1 and 2. On these last two, I do a normal stabilize position only and end up with each having its anchor point key framed as expected. Then, I open a null and add 2 expression point controls. I pickwhip each one of these to one of the stabilized layer anchor points. Now, I lose my sense of where to add the expression. Since it is a null, I'm thinking its position because the anchor point location is different for a null than a regular layer. So, I alt click the stop watch and add the script. But, for one thing, each tracker, since it's on a different instance of the footage, has the same number whereas you have a different number. Anyway, it's in where to apply (and how) the script.

That said, I experimented with going direct to the anchor point property of the master layer, opened an expression box, and pick-whipped it to the anchor of the first layer, +, pick-whip to the second layer anchor layer. Then I surround the whole thing with ( ) and add /2. This seems to work. I understand that there are advantages to going to a null first, but I can't seem to figure it. Is what you suggest and what I did basically the same?

Obviously, expressions is one of my worst weak points. Dale


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 5, 2009 at 12:11:21 pm

RoRK, I understand.

As for averaging, I imported some footage and duplicated twice (now have 3 instances). I labeled them master and stabilized 1 and 2. I performed a "normal" stabilize position only on the last 2 and ended up with each having it's anchor point key-framed as expected. Then, I opened a null and added two expression point controls. For each one, I pick-whipped it to one of the stabilized layer anchor points. Here's where I get lost. Where do I add the expression? I'm thinking the null's position (because the anchor is different for a null than a regular layer). Also, it's not clear if I'm to copy your expression verbatim or if the references to pick-whips means to actually pick-whip. Finally, since each tracker is on a different layer, both have the same number whereas you have different numbers.

Obviously, expressions is one of my worst weak points!

I also tried going directly to the anchor point of the master layer, pick whipping it to the AP of the first stabilized layer, added +, pick-whipped to the second AP, surrounded the whole thing with ( ), and added /2. This seemed to work. I know there are advantages to going tough the null, but I'm not sure how to make it work wrt expression point controls though I think my technique would work directly with the null's position. Are these two ways equivalent or even the same? Thanks. Dale


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Roland R. Kahlenberg
Re: Stabilize Precomposed Layer
on Nov 7, 2009 at 5:19:02 am

[Dale Paquette] " Here's where I get lost. Where do I add the expression? I'm thinking the null's position (because the anchor is different for a null than a regular layer). Also, it's not clear if I'm to copy your expression verbatim or if the references to pick-whips means to actually pick-whip. Finally, since each tracker is on a different layer, both have the same number whereas you have different numbers."

You should take a step back and analyse what you're doing. I think this will allow you to understand things better.

Firstly, each of your trackers provides an Attach Point as a result of the tracking. Your job is to average the values of the Attach Points.

It doesn't matter where the values are, be they in theire original Attach Point parameters, a Null Layer's Anchor Point or Position or Expresion COntrol Sliders. Whether you have $100 in your left or right pocket is immaterial. The fact is you have that $100.

The same holds for your Attach Point values. Where you place them via an Expression pickwhip is inconsequential as their values are absolute values. So to your lastg para, yeah, they are the same thing.

I suggest that you take a look at JJ Gifford's excellent introduction to Expression - http://jjgifford.com/expressions/basics/index.html

You will do well if you work your way to the Vector Math section.

Cheers
RoRK

Sell your AEPs with broadcastGEMs' DVD series of templates. Click here for more


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 8, 2009 at 9:26:22 pm

Thanks, and I will. Out of action for a week or so but will get back on this soon. May I ask another question? My source footage is HDV (basically MPEG-2) which is, of course, highly compressed. As far as motion tracking is concerned, is MPEG-2 as good an any format or would I be better served by opening it in say a 1920 X 1080 square PAR and exporting it as an uncomporessed avi or the like first? Any way, I have to stop till I return home where I can acess my PC and AE. Thanks, Dale


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 20, 2009 at 11:01:32 am

Roland, I'm back on the job. Haven't got to your reference yet but will. In the meanwhile, here's my step-by-step interpretation of your method. To simplify, I tried to average just 2 position only stabilizations (to include rotation, I assume the expression rotation control is used instead of point control). Started with the original plus 2 copies. Stabilized position only separately for 2 of the clips. Created a null and added 2 expression point controls. For each expression point control, alt clicked the stopwatch and added an expression by pickwhipping directly to the corresponding stabilized layer's anchor point (where stabilization keyframes are clearly evident). Then, for the original clip, alt clicked it's anchor point stopwatch and added expression exactly as you wrote but modified for 2 stabilized layers. When I finish, I get an AE warning reading in part- Class 'Layer" has no property or method named 'Tracker 02 Value' So, I'll dig into your reference and see if I can figure it. If you aren't getting too tired of this, I'd love to hear any further thoughts you may have. Thanks, Dale


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 20, 2009 at 12:38:09 pm

Roland, this is my second response this morning. I did indeed read through the reference you provided and will now study it in detail. Based on my first read through, I went back to the expression and made a change - fist, I didn't use the //Start Script notation (nor the //End Script). This isn't mentioned in the article. But, I did have the three lines of the expression. What I did was add a semicolon after the first 2 lines per the article. As far as I can tell, this is now working. I say as far as I can tell because I guess the two stabilized layers are so close to each other that the average is basically indiscernible from its components!! So, I will try again but this time make certain that the two tracks are off from each other by enough to be very clear where the average falls. I will also try rotation this next time. Thanks again, Dale


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Dale Paquette
Re: Stabilize Precomposed Layer
on Nov 4, 2009 at 6:33:30 pm

You guessed it, operator error! What I did was to try stabilization in the new comp. I fixed it by going back to the first comp and adding the second comp. After hiding the original footage, voila - a B&W hicon version. Now, opening the stabilizer leaves the hicon version in in place for tracking! BTW, I'm just desaturating and then using curves to really increase the contrast. The tracking results look good.

Now, back to the averaging. Thanks, Dale


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