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Stabilizing..when your target moves temporarily offscreen?
Here’s a n00B question regarding Motion Stabilization.
I’ve read the Helpfiles, but am still not clear.
I know how to find a stationary object and assign your tracking target to it. Later, you press “APPLY” and AE does its thing. That, I understand.
But what do you do if the object in your video– which is your target object (or targeted cluster of identifiable pixels)– moves temporarily offscreen… then a number of frames later, enters back into your frame again?
In other words, what do you do with your tracking box when your Target object in your video moves temporarily offscreen?
My central object– which needs stabilizing– is a seated woman speaking animatedly, and at some points I had camera-zoomed completely in to frame her face only— then zoom back out again to reveal her surroundings (including the orange upholstered chair whose button is my Target object)
Thanks, David
The only things which matter in life are Art and Children. (Georges Seurat)
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7 Replies
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Hi,
I’m not sure if this is an answer to your question, but I’ll offer my thoughts just because it’s likely to add to the surplus of confusion in the world.
I had tracked footage of an iPod Touch with a photo that needed to be replaced. It starts off screen and rises up into frame. Although I used Mocha to track it and it did a great job, it was not possible to exactly track the bottom edge that started off screen. So what I did (this was in Shake, but the same process would work in AE) I tracked a top corner of the iPod screen and then, moving to a frame where I could see the whole screen, created a thin, solid that was the same vertical length of the screen and attached it to the tracker. Since it was attached to the top corner of the iPod screen, it moved with the iPod, extending to the bottom of the screen, even when the screen moved below the frame. This acted as a ruler that would show me the distance beyond the bottom of the frame that I had to move the replacement image’s corner pin points.
Working backward, as the screen descended below the bottom of the frame, the “ruler” (placed on the edge of the iPod screen) showed me where I had to place my corner pin points. In Shake you can use a viewport node to show beyond the edges of your frame… You might be able to do the same thing in AE by temporarily enlarging the pixel dimensions of your comp.
You might need to rotate the “ruler” so be sure to set its anchor point to the same place as the tracker point.
Of course all this assumes that there is some other point that you can use as an offset tracker point. If you don’t have another point that will let you “proxy track” your real point, then you may just have to move it around until it works. Obviously if the person in your shot is moving a lot, then you won’t be able to use a point off of them to measure where your real point should be.
If you need to just move your tracked points around on screen in AE, I’m not sure you can do it directly on the “Attach Point” keyframes. But if you select all the “attach point” keyframes that the tracker creates, you can copy and paste them to the position keyframes of some other object. You should then see a motion path in the viewer. You should be able to grab the points you want to move and adjust their position on screen.
This may not be what you are looking for and it might leave you more confused than enlightened. If so, my work is done here.
Anyway, there might be a simpler way to do this, but it was what occurred to me at the time, so that’s what I did.
Hope this helps,
Lars
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Hi David,
If it’s a woman speaking and sitting, I suppose the best thing to have done would have been to use a tripod. Obviously this is no use now, but stabilisation is somewhat of a last resort to be used only when you need to go handheld.
Stabilising to a fixed point may make it look a bit artificial aswell, so you may find Andrew Kramer’s recent tutorial on stabilising footage (and getting a little bit of the shake back) useful – videocopilot.net.
Simon Bonner
youtube.com/simonsaysFX -
Hi David,
I’m stilly quite the noob myself, but from a lot of the tuturials I’ve seen here on the COW and over at videocopilot, I gather that you can start your tracking backwards from the frame just before your target goes out of frame. Then, you can track forward from the point where it comes back in.If you are stabilizing the footage and not trying to do something else with the tracking data then I’m guessing that you could manually adjust the frames where your target is out, or, duplicate the clip, trim it to the part where you are missing the tracking data, pick a new target for that portion, track it, then copy / paste or pickwhip the keyframes..
I have a good idea of how to do it – whether or not it will work, or if it is appropriate to your situation I’m not sure. But my big question is, did anyone except me understand what I said above? 🙂
–KTFA
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Alt/Option drag the attach point just before it moves offscreen, here’s a tut:
Tracking obscured objects in video
https://studio.adobe.com/us/tips/tip.jsp?p=1&id=399&xml=aft6tracking
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Okay… fair enough! (-:
As it turns out, there were other fundamental problems with this video footage, too, so I’ll just chalk it all up to beginner’s errors and learn from it.
Thanks, all!
The only things which matter in life are Art and Children. (Georges Seurat)
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If there is any value to it, a last ditch attempt might be to track two sets of points similar to the way Kramer tracks the background in this set extension tutorial… even if you have to hand track a handful of frames for a bit.
https://library.creativecow.net/articles/kramer_andrew/Set_Extensions.php
Brian
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I don’t think the null thing would work for stabilisation, though I may be wrong.
Simon Bonner
youtube.com/simonsaysFX
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