Tracking in blender

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Saras
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Joined: Fri Aug 24, 2012 2:25 am

Tracking in blender

Post by Saras » Tue Mar 19, 2013 4:03 am

I have a project I'm working on in blender where I am using the tracking settings for a video. I put tracking markers on my face for the video, and so far the track is going well, except at one part my hand goes in front of my face and I can't see one or two of the trackers for a couple seconds. What is the best way to go about this and get a good track? One idea that I thought of is guessing where my tracking point was and doing my best try at putting the track manually, but this was tedious and I could see my track was off. Another idea was to disable the tracks that got hidden until I could see the markers again then re-enable it. Do these work? Please reply quickly, thank you.

brianorca
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Post by brianorca » Sat Mar 23, 2013 5:55 am

If you have any doubt about where to place a manual track, then disable it for that frame. You should have enough other tracks on that frame to handle the match. (You hope) A bad track position is often worse than a missing one.
I got a lot out of the training DVD Track, Match, Blend! much of which is also available on YouTube. (But the DVD played better for me with my limited bandwidth, and organizes the lessons better.)

brianorca
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Post by brianorca » Sat Mar 23, 2013 6:09 am

P.S. the YouTube channel for Track Match Blend is here: http://www.youtube.com/playlist?list=PL ... FVFfvFur1g
if you choose that route.

Saras
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Post by Saras » Mon Mar 25, 2013 12:41 am

Thanks. I was already watching the Track, Match, Blend tutorials on youtube. I couldn't find the information about my problem for a while so I decided to ask about it here. Also at one point in the tutorial the man giving the tutorial is talking about focal lengths and then he says the most important thing to do was to get the right keyframes. He then goes on to putting the keyframes he gets into a couple things called "Keyframe a" and "Keyframe b". What did he mean and what does keyframe a and b do? Thank you.

P.S. the part I'm talking about is in part 17: head tracking.

brianorca
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Post by brianorca » Tue Mar 26, 2013 3:29 am

Blender uses every frame to figure out camera movement, but it only uses 2 frames to figure out the camera characteristics. (zoom and distortion)
The manual part is you need to pick 2 frames for it to use. These two frames should be:
A. different enough to get some parallax
B. similar enough that there are enough points in common
C. stable enough that the points have good accuracy
D. have enough "common points" in both the center of the frame, and towards the edge.

Filling these suggestions as best you can will help it calculate the correct zoom and distortion, which helps prevent your virtual objects from "sliding around" compared to the real objects in the video.

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