—Quote (Originally by J-P)—
Looks to me like the surface points at the beginning of the plane are going behind the camera by the time you get to the end. This is why you see the stippled blue line crossing the frame near the end of the shot.
To avoid this, after you draw your shapes, skip to the last frame then press “Align Surface”. If you have the surface switched on in the view controls you will see the four corners snap to the corners of the image.
Rather than making small selections in the water, another thing you could try is to make a large selection running either right down the river, or on the left hand bank. Draw the shape so that it covers as much of the plane as possible (including the edges where the water meets bank, as they are good for tracking). In the layer controls, select “None” for Link to Track. Now you won’t see your shape moving as you track, so you can reposition it however you like as the camera moves. Try to maximise the area of the plane that’s covered as the shot progresses. If you’re tracking the water surface, which is relatively plain, I’d recommend increasing the % pixels to track to 90.
A key concept is that the larger your shapes are, the more stable your tracking result will be.
When you’re tracking with this technique, you can turn on the surface or grid to monitor the results, as you won’t be getting any feedback from the movement of the shapes.
Hope this helps,
I think that some of the shapes are covering rocks that change “planes” too much when passed over. Might be better to focus on smaller patterned areas on that remain relatively flat when passed over.
If you have the time to post me the high res footage, that would be best.
I will be working tomorrow, but otherwise can get back to you next week.