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I'm trying to add motion tracks to a video I've imported. Here is what I have done so far:

  1. Open a clip in the movie clip editor.

  2. Click "Add Marker" and Ctrl + enter image description here to place a marker.

    enter image description here

  3. Press Alt + → to track the selected marker forward one frame.

  4. On occasion, the marker would need to be manually adjusted. I would do this by clicking in the little preview in the properties panel and dragging the background until it lined up properly with the correct location.

    enter image description here

  5. I completed this for the duration of the clip I wanted to use.

This is where things started acting up. I clicked the lock button for the track (the icon next to the eye in the screenshot above) and assumed that everything would stay as it was.

Unfortunately this is not the case. As soon as I jumped back to the beginning and began playing the clip, the marker wasn't in the correct location for each of the frames. Even though I had lined it up perfectly for each frame before, some of the frames had the marker in the wrong place.

How come it moved? What am I doing wrong?

Details

  • Blender 2.69 r60995
  • Windows 8.1 64-bit
  • AMD Radeon HD 7560D

Update:

Here is a screenshot of what happens when I push ← and → to toggle between frames 13 and 14:

enter image description here

Notice that the markers are moving. They aren't supposed to be moving. Something is clearly not working correctly here.

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  • $\begingroup$ The most likely answer is that when you go back to the beginning, you're tracking forward instead of playing forward, and this recalculates your tracking points. Since you've chosen a poor point to track, Blender is having a hard time following it, so the recalculation doesn't line up with how you positioned it. Good tracking points are high contrast, and are very dissimilar from other parts of the image. The point (and remember, it's a POINT) where you've placed your marker in the center of the hub is low contrast, and the spokes are all similar. This is making Blender's job more difficult. $\endgroup$
    – Matt
    Mar 14, 2014 at 14:39

3 Answers 3

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The issue might be caused by inconsistent decoding of your particular video codec by Blender, resulting in variation in the frame sequence you move through on the timeline. My suggestion would be that you convert the video to a discrete image format, like a PNG or JPEG sequence. A typical way to convert video to an image sequence:

ffmpeg -i "MyVideo.mov" -an -f image2 "MyVideo%06d.png"
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    $\begingroup$ I had the exact same problem as the OP, converting my footage to images from my MPEG movie solved this, thanks dude. $\endgroup$
    – Neil
    Jun 28, 2014 at 22:04
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    $\begingroup$ I finally got around to trying this and it did indeed solve the problem. Markers stay put now. Thanks! $\endgroup$
    – Nathan Osman
    Oct 28, 2014 at 17:28
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    $\begingroup$ Oh my goodness, I wish I would have known this sooner. Thanks! $\endgroup$
    – Anson Savage
    Nov 14, 2015 at 3:47
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There are several thing that i think could be going wrong. The reason it is skipping, is because the tracker is mistaking the colors of pixels in the area; patterns as well.

Possible Solutions:

  1. If you can sacrifice the tracking time, perhaps scale the tracking box to cover the whole wheel. The colors in the area are very similar. Low light, and low color diversity tracks are usually harder to track.

  2. If you scale up the box and it still jumps around like that, you can always fix it manually. Go the frame that the box jumped away and use the G key to manually reposition the tracking box.

Further Notes:

The lock button simply prevents you from moving it accidentally manually. I don't think it will prevent the box from re-tracking if you start tracking forwards. Or backwards!

Remember NOT to confuse alt+A (Play) for the little "play-like" tracking buttons on the left panel. Play will just play everything already tracked, where the buttons that look like play buttons will track forward or backwards, overwriting any previous tracks.

Playing and Tracking Buttons are similar. Be Careful not to confuse

I hope this was helpful, or at least gave you some ideas on where to go next. -Ryan

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  • $\begingroup$ As I understand it, the OP manually lined up the tracker on each frame. $\endgroup$
    – gandalf3 ♦
    Jan 13, 2014 at 17:51
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Im having the same problem here, Blender 2.78 Windows 8.1 64bit. I recorded my footage with a samsung S3 phone. MP4 format imported into Blender. Like one of the guys before said its something to do with the decoding of the mp4 video and not the fault of Blender. I analysed the mp4 video I had and it appears my camera dropped a number of frames during the recording process. The video should have been 30 FPS but it averaged less 29.?? . So make sure your footage is perfect. may try splitting it into seperate images as suggested. Cheers.

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