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Tracking difficult and fast panning shots with Mocha for stabilization.

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JonZ MarZ
Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 22, 2014 at 5:22:06 am
Last Edited By JonZ MarZ on Jun 22, 2014 at 5:32:06 am

I've been using Mocha for basics stabilization which is fine, but I'm still having diffucult time to understand how it work, especially with the layers and pixel tracking. I have several shots of Formula one that I try to salvage and I try to keep them on frame as much as I can (they where handheld, not on tripod). What throw off the trackers is people or objects obstructing the view of my panning, or car get off the frame for a fraction of second.

When the cars are coming it tracking fine but as soon they leave the frame it become hard to have a stable tracking. I tried to use several tracking layers but I never understood how well they work together. The tracking go away or I get message to increase pixel used even if I have 100% on them.

I never found a solid tutorial on how to use several trackers on a panning camera. I really want to learn this, I have found myself in numerous situation to use Mocha for better stabilization, since I don't always bring up a tripod and don't have great filming equipment. But I always ended up using Warp Stabilizer when I couldn't figure what goes wrong, but the results are quite messy when I compare to the potential of Mocha can bring on the shots.

I'll be really greatful of some assistance to learn my ways in. I'll be willing to upload my clip and my progress if needed.

Thanks!


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 23, 2014 at 5:05:16 pm

thank you for answering,

I realize using Mocha is a bit ambitious. Some worked great when the F1 was perfect in frame. Other went bad, because a person was blocking the view or the car went off frame for a couple of frames.

I am using Mercalli for quick shot panning and it work so so, the panning is skippy while it has an overall good stabilization, but I have little control over the skippy parts which give an unnatural look, so I was hoping for Mocha to remedy the cause. And Mocha is very good to correct lens distortion shears in the process when it work.

Unfortunately I can't figure how to use multiple layers. Yesterday I had a shot where I successfully tracked 3 areas correctly but I never found out how to 'connect' them into a single tracking.


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 23, 2014 at 7:43:55 pm
Last Edited By JonZ MarZ on Jun 23, 2014 at 7:54:04 pm

I never used adjust track before. Thanks for reminding me this, I will give it a try.

I'm also confused about my example of the 3 tracked areas, I don't even know what I'm doing. I try to have many areas to gather much info as I being told. I cannot make a pass in one shot otherwise the tracking area go crazy. I don't even know if I'm trying to do is possible, or I am doing it wrong, I really have difficulty to grasp and understand the tracking feature by using several layers.


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 24, 2014 at 5:19:25 am
Last Edited By JonZ MarZ on Jun 24, 2014 at 5:19:43 am



I think I figured out what I was doing wrong. Using X-Spline helped much better than using multiple X-Spline layer. My latest track was done successfully using that technique, doing the other way was always giving me an error.

I still get 'kicks' on frames when the target disappear but I can save it in AE. I don't know if there a way to merge the stabilization of when the car disapear in the crowd or when it out the screen. It look weird that it suddenly stabilize on target rather than a smooth transition.







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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 24, 2014 at 8:26:58 pm
Last Edited By JonZ MarZ on Jun 24, 2014 at 8:27:39 pm

Well in the end, I just ended up making a rough Mocha stabilization, then apply apply a regular Warp Stabilization over the composition to take care of the remaining artifacts. The results are more up to my standards I expect :)

So I'm making progress to put good news.


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 24, 2014 at 9:40:11 am

Well I don't like the ending where the tracking end. Like I said, I tracked the ending on a different tracker with shears and all other options on to get rid of the lens distortions, but obviously I cannot do that on the vehicle. I'm looking of a way to 'merge' the ending of the panning with the one that focus the 'exit' without a suddent change. I tried in AE to connect the two, but I am not able to achieve this without loosing the counter shaking effect given in mocha.


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 24, 2014 at 10:41:48 am
Last Edited By JonZ MarZ on Jun 24, 2014 at 10:42:49 am

I think I have figured out the layers isolation. I need some help to understand.

If I draw a contour on people blocking the view on top of the layers I think it actually help the main layer to track down the car without interfering and make a smooth tracking. I'm just not sure how well it work. Is there an stacking order that affect one to the others? I am following some tutorials that explain it a bit but they are hard to follow.


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 25, 2014 at 12:11:59 am
Last Edited By JonZ MarZ on Jun 25, 2014 at 12:39:15 am

Imagineer forum has shutted down and pointed me to this forum...

Yes I meant rolling shutter artifacts. Tracking in AE doesn't work great for me. You suggest to fix the rolling shutter artifact, is there a way to do that in Mocha or in AE?


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Ross Shain
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 25, 2014 at 8:04:46 pm

I believe there is something that you are missing in mocha.

An important aspect is to learn that you can add multiple shapes to the same track layer (X+) button. As long as they are on the same plane, this can greatly help a track.

The trick is to avoid the foreground elements that are moving on different planes. This can be done by stopping and animating your shapes to avoid the fg, then keep tracking. OR you can add shapes for the foreground - making sure they are on a layer above the BG track.

Another technique for panning which is very useful is "unlink" tracking. I would advise you to watch these tutorials:

http://www.imagineersystems.com/videos?tagFilter=tracking+tips&sortBy=Newes...

and

http://www.imagineersystems.com/videos/fundamentals-ex.11-mask-shapes-roto-...

good luck,
-Ross

Ross Shain
Imagineer Systems
http://www.imagineersystems.com


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 25, 2014 at 8:31:30 pm
Last Edited By JonZ MarZ on Jun 25, 2014 at 8:38:40 pm

Thank you Ross!

I will gladly watch those videos. I've watched many of them but sometime it difficult to grasp the topic.

I learned the layers order was indeed very important and realized I was doing it the other way around all that time!

I will redo some of the footage with these new learned techniques and share my findings :)


One thing I need to ask thought, is deleting keyframes of tracked datas is a must when redoing tracking after a spline adjustment? or rendering again will simply rewrite the tracking datas over the previous tracks?


Cheers!


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 27, 2014 at 2:45:36 am
Last Edited By JonZ MarZ on Jun 27, 2014 at 3:07:38 am

Mr Shain,

There's something I am very confused with is adjusting the tracking splines (not in adjustTrack tab, just moving the 'vertices' in track tab mode). In those tutorials they never give a tangible answer what are the splines contours are doing exactly in addition of keyframes. I have a very difficult shot with heavy cam shake and when tracking, the spline and corner pin preview are distorting and go away from the intended target to track. Despite of adjusting the spline throughout the timeline of tracking, it seems to makes things actually worst even with min pixel at 90%. This is the part despite watching many tutorial I have difficulty to grasp because they seem to fitting the role I am giving to it. Despite all that, I managed to have a steady shot by not touching the splines and raise the values in search areas, but the spline is heavily distorted (although the cornerpin and grid seems to keep steady in place).

After that I kind of realized that making precise contour on my targets was kind of pointless but I just can't find an answer to why many tutorials the tutors makes very detailed contours when in most case it seem to not really have significant impact if not making my tracking worst.

Hopefully have an answer soon.

Cheers!

Edit:
Here's a video of me doing what I'm trying to explain. First I try to adjust the tracking vertices to adjust the bad track but seeing the tracking doesn't do what I expect, I just restart and increase the search values instead and the results where infinite time better. Not that I dislike the tracking, I just don't know what I'm doing.







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Ross Shain
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 27, 2014 at 6:21:36 pm

It appears from your video that you do not fully grasp the concept of "planar tracking". Are you sure you have watched the mocha getting started videos? http://www.imagineersystems.com/mocha_Fundamentals

Regardless, if you are trying to stabilize, roto or simply do a match move, the mocha user needs view the shot and think about planes.

You created a shape around the entire car, flag and person. These areas are not all moving on the same relative plane. What I would recommend is creating a shape for the hood of the car, one for the side, one for the window. Each spline has its own "surface" which is the blue box that represents the tracked plane.

Once you track, view the surface. If the track on the surface is not very good, the spline will not follow well. If your track is not very good, and you are animating the spline, there could be a counter-intuitive battle going on. Splines are linked (children) of the tracked surface.

I hope this helps. You can always contact Imagineer support for more detailed help.
http://www.imagineersystems.com/contact_form

Ross Shain
Imagineer Systems
http://www.imagineersystems.com


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 28, 2014 at 3:55:31 pm

Hello Ross, thanks for your answer, and yes this is helping me a lot.

I indeed watched these basics, but I got lost in complexity of some of it so I never totally grasped the planar tracking. Fortunately your last explanation had made me realizing a couple of misconception what Mocha doing and thanks for pointing me out the wrongs. I'm still questioning myself about planar tracking for really rough rotoscoping that shouldn't need complex plannar calculation like my example above. Regardless of your suggestions it couldn't make a difference in better tracking until I crank up the search area. So I'll leave this for now since I have moved since.


Very appreciated!


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JonZ MarZ
Re: Tracking difficult and fast panning shots with Mocha for stabilization.
on Jun 28, 2014 at 4:09:45 pm

Right now my biggest pet peeve is to track a target that get hidden completely by an obstacle during tracking, mostly composed by crowds. I tried to roto the obstacle and put in foreground but it doesn't work as the target get completely lost in tracking once they enter the obstacle. I haven't see a remotely close tutorial in order to counter the problem. I was hoping to manually create some 'prediction' frames with adjust tracking and manual tracking but you can't move all the corner pins at once as far as I see. The only workaround which work best for now is to track the out between tracking before and after the obstacle and export the tracking datas in AE and handle the missing tracking with a couple of Nulls to compensate.


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