Highlighted

AE2020: How to keep attachment point within the center of the feature region?

Community Beginner ,
Jul 28, 2020

Copy link to clipboard

Copied

I'm playing around with the motion tracker, trying to track two red blobs on some PVC. As AE steps through the motion, it seems determined to move the Attachment Point increasingly off center from the Feature Region. It gets to the point where the Attachment Point is so far removed from the center that the Feature Region really isn't over the part I care to track and the whole process fails. However, fixing the region causes the Attachment Point to be in the wrong spot.

 

Is there a way to move the region and attachment points independently or to prevent the drift of the attachment point within the feature region?

 

Screenshot (291).png

TOPICS
Error or problem, How to

Views

54

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more

AE2020: How to keep attachment point within the center of the feature region?

Community Beginner ,
Jul 28, 2020

Copy link to clipboard

Copied

I'm playing around with the motion tracker, trying to track two red blobs on some PVC. As AE steps through the motion, it seems determined to move the Attachment Point increasingly off center from the Feature Region. It gets to the point where the Attachment Point is so far removed from the center that the Feature Region really isn't over the part I care to track and the whole process fails. However, fixing the region causes the Attachment Point to be in the wrong spot.

 

Is there a way to move the region and attachment points independently or to prevent the drift of the attachment point within the feature region?

 

Screenshot (291).png

TOPICS
Error or problem, How to

Views

55

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Jul 28, 2020 0
Most Valuable Participant ,
Jul 29, 2020

Copy link to clipboard

Copied

Your feature region is way too large. Constrain it to only the tip of the stick, not a million square miles of real estate around it. The drift happens because of this and using feature adaptation for every frame. If you realyl want to use such a large tracking region, you might at least want to turn that off (at the cost of more jumpy/ less smooth tracks, though).

 

Mylenium

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Jul 29, 2020 1
Community Beginner ,
Jul 29, 2020

Copy link to clipboard

Copied

Thanks, that helped. I also put a white strip in the middle of the red to give it something more to grab onto. If anyone from Adobe is listening, a way to pick which channel (of RGB) you want to watch would seem to be helpful. Blender has that for its tracker (and why I went to red tape at first!).

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Jul 29, 2020 0
Community Beginner ,
Jul 29, 2020

Copy link to clipboard

Copied

Although, the attachment point still drifts, even with Adapt Feature After Every Frame set to off and Stop Tracking set on when confidence drops. 

 

Snip.png

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Jul 29, 2020 0
Adobe Community Professional ,
Jul 29, 2020

Copy link to clipboard

Copied

Now your feature region is too small. It should include a little free space around the whole red band. 

 

The attach point won't move unless you move it when adjusting a track. You have to pay very careful attention to the cursor. If it turns white and the little + gets even smaller then you are moving the Attach Point. 

 

Here are my steps for motion tracking and it always works.

  • Open the Motion Tracking workspace with the layer you want to motion track selected
  • Make sure that the Layer Panel is selected
  • Magnify the Layer Panel so you can push in on a feature you want to track to at least 200% - 400% is better
  • Select Track Motion and the Tracker will open in the center of the view (that's why you push in first)
  • Adjust the track point so a significant amount of detail that isn't going to change shape and about 5% extra is selected - the default size is too small for most tracking by about 50%
  • Run the tracker
  • If you see the motion path open up the Preferences using the shortcut Alt/Option + Ctrl/Cmnd + ; and navigate to the Display section and select NO Motion Paths because it's nearly impossible to accurately judge a path or move it with all those keyframes showing
  • Open the Graph editor, make sure Value Graph is selected, press U to reveal all keyframes and select Confidence so you can instantly tell which frames are way off
  • Carefully make any adjustments you need in the track making sure that the Attach Point is where it needs to be then Analyze 1 frame forward and one back to make sure that things are tracking correctly
  • Scrub through the track or run a preview on the Layer Panel to see how the track is working

That always works. When you are done, and you have attached a layer or a null to the tracker you can open up preferences again and turn on Motion Paths.  Everything should be fine. 

 

One more thing, if you have a difficult area where the feature region and the attach point get way off, you can go to the last good frame and then analyze one frame at a time. After Effects will to a lot better job of finding the feature region than you can usually do on your own. If there is some constant motion between a few frames and you just can't seem to get anything to work you can always delete the frames that just won't track and insert a few of your own. I also do that a lot of the time. If you select the Feature Center and the Attach Point in the timeline and look at the graph editor you should only see two sets of lines. Both values should be the same unless you have adjusted the Attach Point.

 

I hope that makes things easier to understand. Here's a crazy animated GIF of my process.

MotionTrack.gif

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Jul 29, 2020 1
Community Beginner ,
Aug 01, 2020

Copy link to clipboard

Copied

Thanks for taking the time to write that up! I'll give it a shot!

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Aug 01, 2020 0