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[gallion311]

Hey whats up guys, I'll be shooting a new clip over the weekend and wanted to get some pre-shoot advice regarding my tracking markers.

So the basic effect is inserting a "power cell" into the palm of my hand, sort of like the weapons Iron Man has.

My plan is to align a set of tracking markers in a circle, basically right where I'm going to insert the 3D model. Based on the size of my hand, it's looking like this set of markers will be about 1.5", a little larger than a 50 cent piece glued to your palm.

Now here's the big question: Assuming I do enough movements to calibrate, will this be enough to get a good track? Or will I lack parallax because of the small area of the markers?

I'd like to avoid having to digitally remove markers, so my hopes were that the 3D object would go right over top of them, but I'll certainly go through that step if I need more markers and on a larger area on my hand.

So in a nutshell, would a circle of markers about the size of a 50 cent piece be enough to get a good object track?

Thanks!

[borgus]

hi gallion311,

a small circle of markers of a size of a 50cent coin is probably not enough.
it doesn't help just to have many trackers in one area, try to spread a few
(round about 8? 6? I can't recall) trackers over your reference / tracking object to get more parallaxe out of the shot. you should shoot some
reference images from different angles of your object to aid your tracking
later on (->indirect tracking to get around shots with very little parallaxe)
check out your the object tracking section in the manual to get a few
more hints.

cheers,

Sebastian

[gallion311]

Thanks borgus.

I had figured the small area of tracking markers would be an issue so I'm still trying to figure out what I can do to better prepare for the shot.

I just watched the tutorial on Mesh-Matchmoving (http://ssontech.com/content/boxmatch.htm) and I wonder if that would be a possible solution?

What if I took a straight on photo of the tracking markers on my hand, and built a flat plane mesh at the exact scale, then created and positioned a vertex for each tracker.

Could I then import that mesh, Seed and Lock each tracking point to the vertices in the plane mesh?

Is that a solution that would help, or does that not necessarily solve the parallax issue at all?

[The Happy Friar]

This thread is the same idea you're asking, but it was an arm instead of a palm:
http://ssontech.com/phpBB2/viewtopic.php?p=5622&highlight=#5622

[gallion311]

Lol, yea that was totally me...

Infact it's the troubles I had with that shot that are making me double check this one before I even shoot.

Anyway, so the general take-away from that arm track shot was that I should've spread the trackers out more, rotated my arm more, and possibly used auto-tracking instead of supervised.

Regarding your comment about the reference track (taking 5 different photos, etc) is that the same thing I'm referring to above, about building a mesh (that's an exact digital replica of the trackers) and then seeding and locking the tracking points to the mesh verts?

I've heard about reference tracking before, I've just never seen a practical example so the term is still a bit confusing...

Thanks man.

[borgus]

hey gallion311,

check out page 267 of the manual, there's an tutorial about indirect solving. it's pretty good..

cheers

[gallion311]

Wow, that makes so much sense now...thanks borgus!

So you can take still photos, with an exaggerated amount of parallax, then use their positions to tell Syntheyes more about a shot that barely has any 3D depth.

Now here's the next big question, would using a 3D mesh of my trackers (like the truck tutorial above) still provide any help to the shot or is that a totally different solution, that might just end up confusing Syntheyes?

Thanks again,
Ryan

[The Happy Friar]

I'd assume that the photos and movie should have similar lens distortion & viewing angle. I used photos I took with my video camera and that worked pretty well.

[gallion311]

Hey quick update with a new question.

So attempt number 1 did not go very well. I think I need more trackers, spread out over a larger portion of my hand but I had a quick question about my camera.

It's locked on a tripod so I hadn't really envisioned any issues, but after my first solve, Syntheyes came up with a really bizarre FOV (8.55mm lens and 129.1 FOV) and totally screwed up the shot.

Now, admittingly I didn't do any prep for the camera, so whats the appropriate steps for this type of shot?

Should I setup lines and axis' in the Lens Panel? If so should they be attached to the Camera01 (which is disabled) or the Object? If so, am I supposed to do this first, after tracking, after first solve?

Thanks guys, any help is appreciated...

[The Happy Friar]

I didn't forget about this, I made up my own palm-tracking video and an seeing what I can do to get a good track at the moment.

[gallion311]

Thanks Friar, although I'm trying a new solution and I feel like I may be onto something here.

I was going to post a new thread about it (and still may end up doing so) because I may have figured out a pretty decent method for tracking small 2D surfaces in general.

Here's the abbreviated version:

So after watching the iPad tracking tutorial I realized Syntheyes can handle a 2D track, it's just that the trackers on my palm make up such a small area.

So I figured, what if I could use Mocha (and it's superior planar tracking) to track the small grid of markers on my hand, then use that track to add a digital (much larger) set of markers onto my hand. It basically allows me to track the shot in Syntheyes as if I had a 1' x 1' piece of paper glued to the center of my palm. I can add as many trackers as I want, spread them over as large an area as I want, and even isolate & render that shot without any motion blur.

And the best news is it worked! Even with a rushed test case, it's producing a better, more accurate track than any of my prior attempts.

Here's a quick video showing the pipeline in action:

www.ryangallion.com/mocha-syntheyes.php

Whattya think?

[borgus]

really good workflow... I'll will keep that in mind. You never know when
you need that

cheers,

Seb.

[The Happy Friar]

Very nice! I got mine to track but the glitch happened when I rotated my hand left/right to fast, syntheyes flips the trackers around 90% almost instantly.