After Effects motion tracking help?

khemera777 · **After Effects motion tracking help? -** October 5th, 2007, 11:19 PM

hi there, I'm a college student who has been playing with AE for a while now. To cut to the chase, I'm trying to find out how to do this tracking trick, http://youtube.com/watch?v=enhfApoyhxs. The text flying on people's heads while the camera moves all around and even past them, the focal point is fixed on the subject. I''d really appreciate all the help I can get on this one because trial and error approach would be impossible as for my time constraint on the project. Thanks you all very much in advance.

btw, the movie project I'm working on is about human dependency on technology. The flying text effect I'm seeking help for would be used to show that people don't talk anymore but instead they just communicate through everything technology, texting each other and whatever else.

Raneath

Dezperados · October 6th, 2007, 05:51 AM

Well you need to track the faces, better said magnificant points like eyes which have a good contrast to track. A little bit glow (looks like Trapcode stuff they used) and there you go. Of course, text should be a 3D Layer to manually position it in the perspective of the movie.

ecs-designs · October 6th, 2007, 11:26 AM

To be quite honest aftereffects tracker is...well, horrible lol. But are you asking for advice on using the tracker or do you not know it at all and just need step by step instructions on how to use it?...either way my suggestion would be to save yourself alot of headache and frame by frame correcting and try to get ahold of a tracking program such as syntheyes, or boujou or i think matchmove is another one...plus if you want to text and whatnot to swivel back and forth with the persons head you'll have to do a 3D track anyways (unless you just eyeball the animation) which you cant do in aftereffects.

But it sounds like a really cool concept for a video.

Irish_Laddy · October 6th, 2007, 12:28 PM

I agree, that technique is really cool and looks nice when done right. Why don't you try a new product from The PixelFarm called PFHoe....in fact since you are still in school it's a plus, you get it for free on an unlimited trial to test it out and see how you like it.

it has focal length estimation system, ground plane orientation, and automatic match moving that is built on the same tracking capability of pftrack. It's also available for OSX, windows and linux.

go to pfhoe.com and download it, and then if you want to buy it, it's cheap and affordable. The only downfall is that you can't export or save while learning the trial version.

just a thought.....I like it a lot and find that there is almost nothing I can't do in PFHoe for what I work on.

khemera777 · 03:21 PM

Hello thank you very much for the replies. I guess I could always do the hand tracking but as we all know it's like very unpredictable or effective at all. So, that's why I decided to ask and see if there is a good way to approach this. I've done tracking once before but the camera just dolly out straight so all I did was creating a comp for whatever I put on the plate and a cg camera inside the comp and dolly the cg camera out and eyeball it. Here is that shot I've done for my last movie : http://vids.myspace.com/index.cfm?fu...deoID=12208835.

Dezperados,

I'm just concerned on how to get the text to stay on people's head. The text and stuff like that I can work around it. I just don't know where to start. Let me go shoot some test footage so you can see what it looks like and then it is easier to get advice on. thanks for the reply, btw.

ecs-designs,

I don't know everything about AE tracking but I know a few things here and there. My problem with this one is I don't know where to start. If it was something on the wall that needs replacement I think I can do it with corner pin or whatever but this one involves people walking with text on their head. So basically like you said, it is a 3d tracking with extreme perspective change. Maybe, I should go and do a test shoot of the shots that I need help tracking with and come back and show it to you guys so you know what it looks like. Yea ok, I will be back asap with the footage of the shots.

btw, I always wanted to learn boujou but couldn't find beginner tutorials to get started. Any link to any beginning tutorials for boujou would be much appreciated.

ecs-designs · October 6th, 2007, 03:45 PM

Ive actually found the "wizard" as well as the help files to be very usefull and enough to get started with...but in your case youll have to do an object track which is a little more difficult than just a plain camera track, but like i always say, if its not difficult...than your not learning anything.

khemera777 · October 7th, 2007, 05:35 AM

ecs-design,

Thanks for the advice. After like 7 hours in my school production lab and following the wizard and the help thing in boujou, I kinda know how to track in boujou now. I thought it was really hard. But, I just followed whatever the wizard told me to. Anyways, so I downloaded that first project file tutorial from 2d3 site with the house and the tree thing. I tracked it with the wizard help and got it. But now my problem is how to deal with this tracked data in After effects. This is what I did and got. I tried exported as .ban, having this boujou.aex plug-in in the AE plug-in bin. I guess you can export as AE .ma or just .ma also but in the help section, it tells me to export as .ban and set scale to 10. So I did. In after effects, when I import the .ban I get this the square comp and a another comp. In the square comp, it gives me like hundred of null objects, a solid, a camera, and a reference object. Now I'm lost. I don't know what to do from there. Do you know what I should do from there?

Raneath

Dezperados · October 7th, 2007, 07:50 AM

Never worked with Boujou yet, but you can not import 3D Tracking data into AE because it won´t fit. I mean, the data has to be applied in a 3D app. AE has a 3D Room but not a "real" 3d Environment. Or I don´t really understand your question

tinitron · October 7th, 2007, 08:35 AM

For sure you can import a 3d camera into AE which is the data you get out of the 3d tracking programm. Raneath already did it.

The null objects represent all the points that have been tracked by boujou and their position in 3d space as boujou calculated it. Now you place your text turned into a 3d layer between the null objects at the right position you want.

The problem is you tracked the camera so the text you put in moves correct to the camera but has a static position in the scene. But you wanted the text to follow a person. So you would have to do a 3d object tracking which is IMHO way to complicated. Just track a feature of your person with AE as Claus already said.

khemera777 · 11:32 AM

Dezperado,

Yes, boujou has export format for AE too. I just don't know what to do once i got it in.

Trinito,

I see now that boujou is for good for camera movement tracking. With after effects, do I just track the person's facial features like eyes or put tracking marks on them and track those instead? Also, I've seen poles with tracking marks on them for some film, what are they tracking with that? I think they are tracking subject distance with the subject moving. Is facial tracking good for this effect or do I have to set up a marking pole in the background and track both the pole and the person's face to get the relative distance change along with the x and y movement?

on the boujou issue:

after listening to you, this is what i did. I parent the text later to the reference layer (all the null objects were parented to that referece). and I just pick a null object that I want my text to be there and copy its position and paste it to my text later. and I adjust manually the text rotation and position some more to fine tune it. It render it out and it looks like the text stayed on with the rest of the null objects pretty well while the camera is doing its movement. However, the text layer as well as the rest of the null objects do not stay stuck on the positions they supposed with the original footage on. They all slide throughout (in boujou, they look right on spot with the ladybug thing). I don't know what to do now. oh I also adjusted the pixel aspect ratio as well as composition size of the normal comp and the footage comp to be the same as the square-comp. So right now I have sliding track points, which could be the problem of comp and pixel ratio discrepancy between the normal comp, the footage and the square comp. This is what the footage with the tracking points look like now, all sliding. http://youtube.com/watch?v=5asYM7Kbayg

What did I do wrong?

Sorry for so many questions but I've noticed I like to ask when I don't know something

durexlw · October 7th, 2007, 12:23 PM

Seems to me you have your project settings wrong. I don't know AE, so I don't know what's it called in there, but if you have a different framesize and/or aspect ratio set in your compositor, things will drift for no apparent reason.

Boujou doesn't export them. Make sure the framesize and aspect ratio of your footage, are the same in your tracker then they are in your compositor. If things stick in boujou, I bet this is your problem.

Dezperados · October 7th, 2007, 12:27 PM

Well do you have some footage where we can test on? It might be different with your footage as the youtube one above. I would try the AE method only, set 1 track point, if needed you can smooth the tracking with the smooth expression and it should work hopefully. If you want to stay the text above the heads, you have to track a point of the head, not from the background.
Some seconds of test footage you shoot would be great for solving the problem in detail.

khemera777 · 07:33 PM

Ok, dudes, I got the footage. http://youtube.com/watch?v=BgsbzMssNIE. You may want to click the button to the right of volume for better resolution viewing. The first clip is the text over the head tracking. The second one, I wanted to have like a displaying board on the forehead flashing out messages that the person is supposed to say.

Questions:

1 clip) How should I go about tracking the first clip to get the text following him on his head?
2 clip) How should I go about having a retangular board on the forehead with tracking and everything? I was thinking about putting a retangular tape (green or blue) on the forehead pf the actors, that way I can track with corner pin and key it out since it was green or blue for that matter.

p.s. If you want a high resolution clip to test with or something, let me know because I just posted that small one on youtube for you guys to see what the shots look like.

Raneath

gordonrobb · October 9th, 2007, 02:37 AM

First one could be done with Syntheyes doing a track of just the guys head (assuming it is higher resolution than this), same with the second one, although if he's not moving at all, it would just be a straight 3d camera track. I am sure these guys can tell you how to do it with their compositing programmes.

khemera777 · October 9th, 2007, 03:21 AM

gordon,

AE is the only program I have so the approach to do this job with AE would be possible for me, none others. Even though, I also have boujou, I don't even know how to use it properly with AE to get the tracking right. So, basically, my only way of doing this is AE.

Raneath