Some one help please!


I'm writing because I need some serious help understanding tracking. I have a quick 60 sec shot where I need to add some body wounds to the character. The problem is when the director shot the footage they didn't add any markers so I can track with.

Plus, I’m a noob when it comes to tracking to start with. I have watched many tutorials, bought mocha import plug-in but whenever I try and track the footage mocha gets lost.

Even if I go frame by frame adjusting the points, the actor just moves around so much (bending his arms out of frame and twisting them) that nothing I do helps.

Please, I am begging for some help here. I can post the clip if it would help to see what I am talking about. I really have been working on this 60 second clips for 6 months now and I’m at my wits ends.

Thank you,


It’s quite possible the arm you’re trying to track is not trackable, depending on the shot. A video would help, so yes, if you can upload it i’ll take a look.
If the actor is twisting their arms too much you will lose the plane of information to track. You may have to track as much as possible then do the rest manually.
Adjusting the spline points will not help your track. The spline is just a search area, not the actual tracking information. When you’re tracking, turn on the surface and/or grid to watch how the track is going.

It’s normally a combination.
For the arm, you’d need to track in the element like tctdvm says: Do as much as possible then tweak.
Since you’re dealing with a moving arm, you’d probably want to use corner pin to match the plate, but it’s hard to get it looking right, as you don’t have a lot of detail to work with there.
Corner pin is essentially a 4-point distortion. This means it can warp the insert you want to apply it to rather than just moving it around in XY space, which is what transform does.
You only need to export shape data if you need to mask out an area.
Trying different trackers is probably not going to help, because the underlying problem here is that the arm is very smooth and there are light changes on very little detail.
Do you actually have to do the whole shot? That seems like a very long take.

Nothing is impossible… just bloody expensive and crappy looking in the end
On difficult shots like this, I track what I can first, as best as I can. You may need to track parts with the skewing turned off, maybe even the scale and rotate, and use translate only.
Use this first tracking pass to create tracking markers or other shapes that can be key-framed to ‘stick’ to the arm. fine tune those areas and then render them out and retrack them.
Good tracking is a process of refinement. rarely to I get to use 1 track the first time. Rarely do I use one tool for tracking, either.
60 sec is forever, ouch.

yeah, no kidding, cut to a closeup or something
No software tracks better than mocha.
You would use Syntheyes to generate a 3d camera. You still have to feed it tracks or track points. I use Mocha to track difficult shots and then use a script I wrote in python to convert the mocha tracks to be compatible with syntheyes. None of that will help you with this.
I’m not really sure which export settings to use either. I seem to have the best luck with “Corner Pin” and then copy / paste onto a precomp in AE.
Kinda opening a can of worms here.
Seems like you need a bit of foundation knowledge of compositing first…
there’s a good book out there (I might even have a technical editor credit :slight_smile: ):
Professional Digital Compositing: Essential Tools and Techniques
Really good book, actually. Chapt 2 (I think, it was a few years ago) gives you what took me 10 years to learn.

Thanks for taking a look and the advice. Right now I just have Mocha and the After FX tracker. I’m not sure yet tracking is area I really want to get into heavily but I’ve heard Syntheyes is a good program.
Are there any others you might recommend that work better then what I mentioned? Thanks.
I guess my main problem is all of this is so overwhelming, like what export setting I should use, corner pinning, tracking data, shape data. I try and follow tutorials but I can never find one that really explains WHY use the settings they do.

I think if I understood that better, I might understand how to work the program better.
Again thanks for the reply and the help.

First, thank you for any help you can provide. Here is the shoot. If the link doesn’t work let me know and I’ll try a different site.
So, what I need to do is to track his shoulder and forearm to make it look like the skin has been cut.
I’m begging to get the impression that, that is going to be impossible. But please if you can help, it’ll be much appreciated.