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Motion tracking gone horribly awry...


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 Okay, I've finally figured out that the "position constraint" is best placed in the general region of where the 3D object will be composited into a scene (no thanks to all three of the C4D courses that I've purchased), and I'm getting better with defining "vector constraints" as well...but, for the love of God, getting a "planar constraint" to work is absolute torture. That said, I know what is wrong, I just don't know how to fix it.

 I've got a very complex piece of video that scans a city skyline. The shot is from a drone, so it does have some pivot issues, but the biggest issue is that after doing a full 3D solve utilizing as many as 2500 tracking points with optimal spacing and search patterns...the ENTIRE scene appears backwards. IE, all of the objects tracked in the foreground are much further away than the skyline, which is in the distant background. Masking helped to clear up some of the issues, but when I try to define a plane constraint, even if I try to flip the axis...I get an awkward ground plane. Furthermore, tracked points in the scene that appear to have similarly sized tracking "dots" are nowhere near each other in the actual scene preventing even a rudimentary X,Y and Zed vector constraint without going into 3D view outside of the camera to seek out two that SHOULD be vertical and/or horizontal.

So, tell me fellas...what's the secret? What am I doing incorrectly? (I'd upload a scene file, but it's HUGE, but I'm attaching a still for reference)

 

535706683_MiamiFreewayOverhead00_00000.png

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Drone footage is a bit notorious for problems like this. You try and keep them 'nailed to the sky', but the wind and GPS drift has other ideas, and our trackers definitely notice ! 🙂

 

I have hardly done any tracking myself, so I am not the best person to advise here in terms of solutions, but I have read various posts around the net over the years where similar questions have been answered and strategies suggested. I have a feeling the phrase 'manual track' comes up a lot in those posts !

 

You just gotta hope someone with a lot of tracking experience can notice this post and advise...but I bet they want the scene file and video footage when they do, so probably best to have it up in dropbox to link to should anyone here express an interest...

 

CBR

 

 

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Well, I certainly appreciate your time and info. I'll cross my fingers. The main issue for me is the fact that the tracking points are logically reversed. The buildings appear to provide most, if not all of the near tracking data and the ground...literally right in font of the shot appears as if it were in the distant horizon. One would expect that "reverse axis" might offer something in the way of correction, but it most certainly does not. Thanks again.

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I wonder if there isn't anything you can do to the tracked footage to increase the importance / prominence of foreground detail - even equalising / shadows / highlighting it so those areas are brighter may help some. And of course the footage you track doesn't have to be the footage you use, so in theory you could track off one that was optimised for that then replace it with the original later or in post. That would rely on not having your tracking points disappear when you updated the footage, and I don't know if that is the case or not, so you'd have to let us know !

 

CBR

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