Need help with this simple object track

[Prankreas]

Hi,
Sorry if this is a duplicate post but the first time i posted it didnt work...

I'm trying to put some animation on this guys arm, the camera doesnt move. I have done many camera tracks in synth eyes without problems, and i thought an object track like this would be very easy, but the software refuses to obey.

if anyone would take a look at the clip or the syntheyes scene i would be very grateful.
http://betheridge.dreamhosters.com/t...d_camtrack.zip

thanks

[gordonrobb]

Have you posted on the SE forum? I find they are very helpful.

[Prankreas]

no i didn't i was looking on the ssontech site yesterday, and couldnt find the forum (well i only looked for about 10 seconds) i've found it now. I'll look around there, but if anyone can help here please do! i need all the help i can get

[anthony113]

3d tracking apps are used to derive the motion of a camera used to film a scene. what you want to do is called matchmoving. hopefully you know the focal length of the camera, film back of the camera and distance to the hand.

what you want to do is create a new 3d camera and set it to the same parameters as the one that filmed the scene. once you have that, you can create 3d geometry that matches the shape of the arm/hand and animate it accordingly. if you only need the wrist area (bare skin), an easy way to do this would be to create several nurbs circles and loft them

[dahveed]

This isn't matchmoving, well, not in the sense that any of the camera trackers can really help. What you really need to do is create the image plane in your animation program and do this "manually", i.e. create a model of an arm and such and animate it to match with the footage. Or, if you're supremely talent, you could forgo the 3D watch and simply draw a 2d watch frame by frame in some 2d animation program.

So really, it's a match-animation problem. The only way matchmoving is involved is if you wanted to get the distance/focal length of the camera to match up. But this can be easily done by visually experimenting with model to camera distance.

*EDIT*

THinking about it after my post, i looked up Syntheyes (haven't worked with it much), and I see it has an OBJECT tracking capability. Didn't know that, and that's obviously what your post is refering to. Still, my advice applies, it isn't matchmoving. That's important, because if you are trying to track using syntheyes motion tracking mode, it will totally not work. Object tracking is a whole different mode (i don't know that from using the program, it just makes sense...there's two wholly different goals, one is to figure out the camera (motion tracking/match moving), one is to outline objects as they move through a scene. The result of one is 3-d points (matchmoving) and the other (object tracking) is 2-d.). So yeah, go read the documentation carefully. Syntheyes prides itself on tutorials and lengthy documentation, something tells me you didn't read it.

*EDIT* #2

Just to try and clarify, there's no way syntheyes could determine the 3-d space that the hand occupies. 3-d space can only be determined from stationairily (is that a word) tracked objects that are tracked by a *moving* camera. Without this parallax (http://en.wikipedia.org/wiki/Parallax) it's impossible to determine...well, not impossible, but it's certainly outside the scope of any matchmoving program

*EDIT* #3

This is great, this question came up in another thread, here are some supplemental answers:

http://www.vfxtalk.com/forum/need-he...le-t11419.html

Yup, gotta do it by hand.

[Prankreas]

thanks dahveed,
I have been through the syntheyes manual, admittedly scanning for what i need. I did the two tutorials closest to my problem, but the software simply refuses to do it. I'm still adamant that it can be done in syntheyes. The thing is, the shot is going to be so short, it's probably worth doing by hand anyway.

Here is what I managed to to in After Effects with one tracking point and a 2d picture of a digital watch. I animated a warp transform effect to try and get more perspective when the arm is at angles to the camera.

http://betheridge.dreamhosters.com/t...ack_TEST01.mov

I put a scuffed up b&w filter on it just to give it a film feel, as the final version will be shot on b&w super 8.
It looks very mediocre, but i think with more effort it could work, especially if i shoot the final thing without moving my arm very much, keeping it straight on to the camera!

[gordonrobb]

My understanding of what SE could do is that it can track the motion of an object, for you to relace/add your own geometry - which is perfect for what you are trying to do I think. Problem is (and bear in mind I have done no object tracking in SE), it requires that the object, or at least the part you are tracking, is solid (i.e. doesn't have different parts of it moving in relation to other parts). For example, you could track a head, but if the person was talking, you could not use any tracking points in the jaw or mouth, or any other part of the head that is moving.

The problem with your shot is that you hand moves differently in relation to your wrist. Even your wrist is twisting slightly, so SE will struggle with this. Unless you can isolate a part of your wrist that has enough trackable features on it. If your going to do it in SE, you need to have more movement, not less, then it will get a good 3D solve.

I'm not sure if you have or not, but if you haven't, post your question on the SE forums. There are some guys there that are going great things with object tracking.

[Prankreas]

@gordonrobb

yeah for an SE 3d solve you need more movement than i have here i think. But i still think its possible with SE to manually track the freckles on my wrist. All i really need is the movement of those 3 main freckles in relation to each other to get a 2D picture to move in the same way. I think i'll do it by hand. Would still be useful to know how to do this acurately though. Imagine the shot was 15 seonds long, I would not want to be the mug that sits there and animates it by hand!

[gordonrobb]

If you have no 3d movement (ie the wrist will always be pointing to the camera at the same angle, even if it moves a bit), you could try a tripod solve.

[Prankreas]

yeah tried doing all that. SE just errors when i start the solve, saying something like cannot get first frame info. In fact i've manually tracked the points i need, I just want SE to export those points in 2d so i can use them in after effects but i have no idea how to do that. You cant seem to do it without SE doing a auto solve first.

[durexlw]

The way this is setup, it won't be an easy job. You may be able to pull this off with Monet (or Mocha for that matter). I quickly tested, and I would get to a fair result if I spended a few hours on it.

I would suggest however, putting a few small red dots on the hand, wrist and especially where you want the thing replaced. Small dots will do, easy to remove in post and it will make your solve possible. SE wouldn't be my apps of choice though, unless you extend your footage:

Run around with the camera first, so you have enough paralellax on the background to solve your camera. Then bring the hand into frame, track the hand (preferable also using red dots) and resolve those tracks into the initial camerasolve you made.
This will give you a pointcloud to work with. I don't know if it's worth the trouble though. Monet can probably handle this track just as easy. Getting the final result won't be that easy task to get it convinving though... the skin stretches and twists and the eye notices fast if a solid thing is pasted on... expect to spend a few days at this shot before you'll fool your mother with it.

My advance: reshoot it, place some tracker dots and think carefully about their placement. Use a 2.5d tracker.
Or go for a 3D track, but make sure you get enough data to resolve your camera before you even bring the hand into play.