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Davor

Tracking and replacing paper in a shot

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Hey all,

 

I'll be tasked with some post work on a shoot that we're doing. There'll be a few shots where a person is handling some paper and they're asking me to put in a page from a magazine on it. There will be movement as paper bends and such in the person's hands.

 

I've tried motion tracking in AE with like 4 points on top and bottom edge and 6 points on the sides, and using expression linking those points to puppet tool pins. It works in tracking but the image gets super warped around the edges, like it's bubbling up.

 

So my best next case is having the shot paper have a grid printed on top and then I just use that grid to follow frame by frame using Mesh Warp effect. Bit pain in the butt, but will do the trick. Unfortunately I can't think of any way of linking the tracked data to the "Distortion Mesh" of the effect.

 

I'm just curious if anybody else has any ideas on how I could get this to work where I can use tracked motion with some plugin somehow?

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So my best next case is having the shot paper have a grid printed on top and then I just use that grid to follow frame by frame using Mesh Warp effect.

 

 

That actually sounds like a decent idea, and if the shots of the paper being handed off are short enough (less than 2-3 seconds) I'd probably try that. Use Mocha to get a good perspective track, then mesh warp the result to match the plate. You could also try using the puppet-tool since you can actually attach the puppet pins to tracking data using the expression pickwhip.

 

I'd also make the digital "page" slightly bigger then the real page on the plate so you can get away with a little bit of discrepancy. Definitely sounds like a lot of manual tweaking though.

 

joey

 

p.s. I just had a really dumb thought. What if you printed a UV Pass onto a piece of paper (like this one:)

 

uv_linear.jpg

 

And then used RE:Map to replace the image on it. I doubt it'd work but might be worth a quick test.

 

joey

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Humm I didn't think of using Mocha, since it only works with rigid tracking but maybe it will work in addition with to get me aligned on the somewhat plane, and then possibly need to do less moving of the points within Mesh Warp.

Thanks! Will give that a go.

 

The RE:Map thing sounds like a good idea... just not too sure if the lighting in the shot will mess with the UV Pass, with potential shadows and maybe a glare that might be caught on the paper. But it's worth giving a shot and see what happens.

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Mocha is definitely your best place to start. Curious Turtle has a tut that covers pretty much what your asking about. It's number 4 I believe. I've bought and used a bunch of their training and it's really pretty decent... despite the impression their website may give.

 

Hope this helps.

 

 

http://www.curiousturtle.com/79-paid-tutorials/imagineer-systems-mocha/150-master-mocha-vol-1-production-effects-with-mocha-pro-after-effects.html

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Thanks for that, although I can't seem to get their "shop" to work, and I might be out of time to give that a try, shooting is tomorrow. And I have a feeling it will get me part of the way but in a lot of the shots the paper will be actually bending and warping. Will try and shoot for it and maybe see if the shop works and the price is right, will give it a looksy.

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I think you're in for a lot of manual tweaking and fiddling, I can't think of an automated way to do this.

 

The Re:Map solution is really unlikely to work, it's extremely sensitive to even slight variations in value, getting a texture to lock to the paper would be a miracle.

 

If it was my job, I think I'd do as much as I can in AE with Mocha, then on the shots where the paper is rolling I'd get the shot tracked i.e. Syntheyes/Foundry Tracker, just to get the camera movement nailed, then set up a replacement page in Cinema/other 3D app, with bend deformers to get the paper curling. If you've got a locked down camera that's easier of course. Then it's a case of eyeballing it as close as you could get. A lot of fiddly work, but if the shots aren't too long and the page doesn't flap around too much it should be manageable.

 

Normally at this point some sprightly upstart jumps in and points to 'SupaPaperTracky' plugin or something that I've never heard of, and all your problems are solved ;)

Edited by ChrisC

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Yeah, I've done a test with using a white paper with a grid printed on most of it, and then used that same file, made it a comp and used it along with Mesh Warp to match the placement. It is going to be mostly a frame by frame situation but it should work. I am fairly surprised that there isn't an actual "warp to grid plugin" out there already.

 

I believe the camera will be locked off in all the shots (fingers crossed) but I don't think I'll be taking it into 3D, using the bend def and such sounds like it would be more of a hassle to get "just right".

 

I'll update with any progress... just in case somebody else comes along that is trying to do the same thing in the future some time.

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So, dumb question: why not just print and shoot the magazine page? This seems like a ridiculous amount of effort to go through to just put print on a piece of paper.

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The paper is being handled and the actors need the reference, so just doing a 3D paper would be even more of a challenge.

 

The spot is for a magazine page that hasn't been designed yet. So I'll have yo wait for them to lay it out.

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*Face-palm* Of course! Sorry, it's clearly not your fault, I just hate when clients do this shit and we end up going around our ass to get to our elbow rather than just doing things in an order that makes sense. I mean, the amount of time it takes to lay out a single magazine page and print it vs. tracking and compositing a page in post across multiple shots is quite a disparity. I'm dealing with similar issues today, so I'm a bit sensitive to it at the moment. Sorry for the mini-rant. And hey, it keeps us all in a job so hooray for that! :)

 

R

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The spot is for a magazine page that hasn't been designed yet. So I'll have yo wait for them to lay it out.

 

Wow, didn't even notice that the page was a still, just assumed it was going to hold animation.

 

Worst job of the month award. You win!

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the amount of time it takes to lay out a single magazine page and print it vs. tracking and compositing a page in post across multiple shots is quite a disparity.

 

The person who needs to approve the page layout is probably on vacation:)

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Yah, but it could have been way worse. I'm glad they actually came up to me and told me about the shoot before doing it. I saw what they were planning on using (faded green construction paper with barely different green little squares on the corners, which wouldn't have given me any "data" to work with and would have been a pain to key out and replace with magazine page.

 

The magazine is actually for a Christmas themed edition, they're killing two birds with one house'd stone, doing a back to school one and an x-mas one all at the same time/place. Thankfully the back to school magazine is done so they will use actual pages for that... although those shots would have been the easier ones to work with. Oh well... that's why I make the big money!...

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