Wire Removal artifacts where wire attaches to object

I have to do some wire removal and all is going well except for where the wire attaches to the object.

The shot is an object hanging from a fishing line and spinning while the camera does a slow arch around the object. I’ve tracked the background and animated my mask around the wire. I even animated a holdout mask around the object so Mocha doesn’t use those pixels for replacements in the remove. But I’m still getting distortions right where the wire touches the spinning object.

What’s the best way to tweak this and clean it up?
(I would send you a screen grab, but there is an NDA on this project).

P.S. Loving all the tutorials you make and would love to see one on wire removal.

The remove module uses the background track pixels to replace the foreground layer. Without seeing the scene, it sounds like there is not enough well tracked, clean information right at the place the wire touches the object.

This might be handled by painting some clean plates and using the clan plate insertion (in remove module) or possibly simply augmenting your remove with some paint & clone outside of Mocha.

We would be happy to sign an NDA and look at the clip.

Best,
Ross

Thanks for replying. I’ve been thinking about this shot in the back of my brain all weekend. I bet the track isn’t strong enough. The background directly behind the hanging object is an overcast sky, so there isn’t a lot of data there. On Monday, I think I will try an offset track with a different section of the background to get a better track. I’m also thinking that I should pull in some handles and track those to give the remove module some more pixels to work with.

Hi Sam,

That sounds like a good plan. Also, some shots will just need some hand tweaking, so if you can’t get a good track on the background you can try another technique. If the wire is only a few pixels wide, you might get better results with mocha roto for the wire and offsetting the background. Since the BG is a cloudy sky, you will get away with a lot. And you can hand touch up if one or two frames isn’t reading correctly over the spinning part of the object with rotopaint.

Cheers,
Mary

Hi Mary,
For clarification when you speak of offsetting the background I would do that with roto shapes in Mocha and layers in AE, or is there a way to do that completely inside of Mocha?

The offset track wasn’t working very well because the best objects to track are not on the same plane. I might try to increase the size of my tracking area and the size of my holdout mask.

Thank you for responding to me on this forum. Your tutorial videos have been very useful in helping me learn Mocha and increase the services I can provide, thus my revenue for 2018. Mocha is one of the best investments I’ve made in my business.

Gotta get back to work, just got ANOTHER logo removal request.

Hi Sam,

You’d have to do that in a compositing program like AE to make things easier, but you could technically do it with the insert module too. You’d make your roto shape for your wire (very narrow) and then use the plate as the insert layer, you’d align your surface tool on the first frame of the footage so they footage would be perfectly aligned, and then you could use the insert module to make the wire matte apply to the insert. Then you could simple move the surface tool a few pixels to the left or right to offset it.

But I’d just use a roto shape in AE and move it there, you have a bit more control that way and it’s not complicated.

Cheers,
Mary

Ok, the background track is solid. The shape around the wire is animated well. I think the issue is that my holdout matte around the spinning object isn’t setup correctly. The remove module seems to be using pixels that are inside the holdout matte when calculating the remove during part of the rotation.

The holdout layer is above the background and below the wire layer in the layer stack. Both the holdout and the wire and “Link to track” the background. The remove module’s “Input Clip” is set to Input.

hmmm

Can you email me a screenshot? I’ll need to see the whole screen and your settings. maryp at borisfx.com

Cheers,
Mary