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corner pin tracking when you can’t see the corners…
I’ve got a client that is fond of making me place logos on the sides of their trucks, not usually a problem using corner pin or motion tracker. The most recent bit of footage was a lockdown shot of a semi truck backing up to a warehouse dock. It was shot using an ATX200 camera with a wide angle adapter over the regular lense and positioned very, very close to a long semi truck. The camera is so close and the truck is so long, I can’t see more than 2 corners at a time, and there are a few seconds where I don’t see any corners. The camera is also giving a nice bit of fish eye distortion to the vertical straight edges.
SO what I’ve tried is creating a grid in a comp that I could line up with the reflectors on the truck as incremental tracking points, and putting that comp on a 3d layer over the footage and rotating it to the approx angle of the truck side. The lens distortion then causes issue as the truck backs through the frame from left to right. The verticals bend on the far edges and the reflectors on the side of the truck become un-equadistant and don’t line up with my grid guide.
I also tried setting up the AE camera next to a plane like the real camera was set up with the side of the truck. 3 feet off the ground, 15 feet from the corner of the truck and focased to infinity. I set the AE camera to as close as I could figure out to the real camera settings, from 20mm-30mm. That was less successful than just sliding a 3d comp layer.
I did see a boris effect for optic distortion that may work for the warping, but the tracking is still a problem.
Anyone have any better ideas, or am I even on the right track?
Thanks..
Mindy -
4 Replies
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This from Adobe Support might help.
Tracking obscured objects in video
https://studio.adobe.com/us/tips/tip.jsp?p=1&id=399&xml=aft6tracking
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Ignoring the distortion for a moment:
Is there a rectangle *within* the 4 corners that you CAN see within what you want to replace? If so, our RE:Map has a 4 corner pinner that allows you to extend the texture past the 4 corners that you are tracking (and can, then, extend to the corners and edges you cannot track because they are offscreen). This way you can track sub-rectangle within your billboard, but replace the whole billboard even as edges and corners go offscreen.
As to the distortion… you might want to do the following: undistort (using AE’s reshape or the warper we have in RE:Flex), corner pin, then distort back. You know when your undistort is working properly (or at least “good enough”) when straight lines in the real world (such as the edges of the billboard you are replacing) should map to straight lines in the image you are working on in AE. I don’t suppose you took a reference shot with something that can help you define the distortion of the camera lense? If not, the edges of the rectangle of the side of the truck should suffice. If you perform the undistort on one frame, then the undistort will pretty much be good for all frames (since you said you have a locked-off shot). Then you can corner pin, then add the distortion back in (or, more appropriately, just re-add the distortion to the texture you are using to corner pin and composite back onto the original live-action).
Hope this helps. Let me know if anything is unclear.
Pete -
yikesmikes & Pete,
Thanks so much for the timley relpy 🙂
I don’t have the Re:Map effect on my machine, but have put in a request to get it installed. I can’t quite see one consistant point thru out to track, but what I do have is a series of red & white reflector tape stripes and I can track those for almost 3 seconds each, then jump to the next one when it comes into frame. By doing that, I think I can use the technique that yikesmikes’ tutorial laid out and keep the attachpoint in the same place while moving the trackers to the second and third reflectors as the others leave the frame. And if re:map can extend the texture past the corner tracking points, I think I’m in business. I am also trying to straighten out the footage before the composite…that seems like a no brainer, but I was trying to effect the overlay rather than correcting the inital problem, duh!
I will let you know how it goes when I get re:map installed.Thanks again for the insight!! Sometimes it just takes a different POV…
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[gfx_diva] “I don’t have the Re:Map effect on my machine, but have put in a request to get it installed”
Keep in mind that you can use the demo version until you know it meets your needs (that may or may not be obvious, so I thought I would say it out loud). The URL for RE:Map is here: https://www.revisionfx.com/rmap.htm and the installer page (which will install a demo if you do not have a registration key) is here: https://www.revisionfx.com/rmapdownloads.htm
Cheers,
Pete
https://www.revisionfx.com
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