Tracking markers fail to track near the left and right edge of a movie clip. #36587

Closed
opened 2013-08-28 01:27:27 +02:00 by Lars Soderlind · 8 comments

%%%--- Operating System, Graphics card ---
Windows XP 32bit sp3
Nvidia GeForce GT 240

- Blender version with error, and version that worked ---

tested error with 2.63, 2.68 and 2.68-r59489-win32 from buildbot

- Short description of error ---

Tracking markers fail to track near the left and right edge of a movie clip. Even if margin is set to 0.
This issue is more prominent when using big markers and does not seem to happen near the top or bottom edge.
Refine:Forwards on the other hand tracks fine near all the edges.

- Steps for others to reproduce the error (preferably based on attached .blend file) ---

Extract the attached zip file containing .blend and a simple image-sequence.

Open .blend and select any marker you want to test and then track it.

The following happens:

Marker A tracks all the way to the bottom. (It may start to drift at the very bottom in this test but that is not really a problem for me in real footage and not the issue I am trying to point out here).

Marker B stops before it reaches the right edge. This happens sooner if the marker is big, so it may not be noticeable with smaller markers.

Marker C is close to the top edge and tracks fine but also stops a bit early when reaching the left side.

Marker D fails to track because it is close to the left edge.

When a marker fails you can click the preview window to place the marker and then press Refine:Forwards and refine works fine where the marker previously failed.

Also try to move marker D farther from the edge and notice that it will start to track fine when it's not too close to the edge.
%%%

%%%--- Operating System, Graphics card --- Windows XP 32bit sp3 Nvidia GeForce GT 240 - Blender version with error, and version that worked --- tested error with 2.63, 2.68 and 2.68-r59489-win32 from buildbot - Short description of error --- Tracking markers fail to track near the left and right edge of a movie clip. Even if margin is set to 0. This issue is more prominent when using big markers and does not seem to happen near the top or bottom edge. Refine:Forwards on the other hand tracks fine near all the edges. - Steps for others to reproduce the error (preferably based on attached .blend file) --- Extract the attached zip file containing .blend and a simple image-sequence. Open .blend and select any marker you want to test and then track it. The following happens: Marker A tracks all the way to the bottom. (It may start to drift at the very bottom in this test but that is not really a problem for me in real footage and not the issue I am trying to point out here). Marker B stops before it reaches the right edge. This happens sooner if the marker is big, so it may not be noticeable with smaller markers. Marker C is close to the top edge and tracks fine but also stops a bit early when reaching the left side. Marker D fails to track because it is close to the left edge. When a marker fails you can click the preview window to place the marker and then press Refine:Forwards and refine works fine where the marker previously failed. Also try to move marker D farther from the edge and notice that it will start to track fine when it's not too close to the edge. %%%
Author

Changed status to: 'Open'

Changed status to: 'Open'

%%%The issue with markers A, B and C is normal I think.
You start to lose tracks when the search area goes outside the frame. That's why you seem to lose the tracks to early. It's when the search area starts to extend outside the frame.

The issue with marker D is odd as it behaves differently from marker D. Marker C tracks sideways and doesn't seem to care that the search area extends above the frame, whereas marker D should track down and fails even when I shift the search area inside the frame. %%%

%%%The issue with markers A, B and C is normal I think. You start to lose tracks when the search area goes outside the frame. That's why you seem to lose the tracks to early. It's when the search area starts to extend outside the frame. The issue with marker D is odd as it behaves differently from marker D. Marker C tracks sideways and doesn't seem to care that the search area extends above the frame, whereas marker D should track down and fails even when I shift the search area inside the frame. %%%
Author

%%%Thanks for testing but I think that the way Blender motion tracker works, search area actually can go outside the frame without problem, and it's only when the pattern area reaches the edge it should stop.

Try changing marker B to pattern area size 180 and search area size 200. It will stop before even the search area reaches the edge. Then change the search area to 400 and it will track to the same spot. The marker should probably work for another 4 or 5 frames with this pattern area size. Search area size makes no difference, only pattern size does. %%%

%%%Thanks for testing but I think that the way Blender motion tracker works, search area actually can go outside the frame without problem, and it's only when the pattern area reaches the edge it should stop. Try changing marker B to pattern area size 180 and search area size 200. It will stop before even the search area reaches the edge. Then change the search area to 400 and it will track to the same spot. The marker should probably work for another 4 or 5 frames with this pattern area size. Search area size makes no difference, only pattern size does. %%%

%%%I don't know about the internals of the tracker, so I cannot make an educated guess as to what is going on. When the marker loses its track can depend on many factors, including the speed of the feature, the relative size of the pattern and search area, etc. I do think that A, B and C are normal behavior that could perhaps be improved with tweaks. But the behavior of marker D is really counterintuitive.%%%

%%%I don't know about the internals of the tracker, so I cannot make an educated guess as to what is going on. When the marker loses its track can depend on many factors, including the speed of the feature, the relative size of the pattern and search area, etc. I do think that A, B and C are normal behavior that could perhaps be improved with tweaks. But the behavior of marker D is really counterintuitive.%%%

%%%Fixed in svn rev59765. Thanks for the report, closing.%%%

%%%Fixed in svn rev59765. Thanks for the report, closing.%%%

Changed status from 'Open' to: 'Resolved'

Changed status from 'Open' to: 'Resolved'

%%%Lars, i've added the footage and .blend from the attachments to our regression test files collection with you mentioned as an author of the dataset. Hope you don't mind :)%%%

%%%Lars, i've added the footage and .blend from the attachments to our regression test files collection with you mentioned as an author of the dataset. Hope you don't mind :)%%%
Author

%%%I don't mind at all. I'm glad you found it useful.%%%

%%%I don't mind at all. I'm glad you found it useful.%%%
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Reference: blender/blender#36587
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