How would you replace the bg on this shot?

[Marvin Nuecklaus]

Hey there,

I consumed all Fusion courses here on Lowepost, particularly the sky replacement and rotoscoping one.

Unfortunately, I couldn't find a technique that is quite applicable for the shot attached. 

My goal is to replace the BG with a desert shot so everything from where the fence starts. 

Do you guys have any advise how to approach this? Luckily it was shot in R3D in 6K so lots of information. 

[Tom Evans]

That would require a combination of techniques. I would start with luminance keys, but for the top part I'm afraid you will have to sharpen up your roto skills. Watch Lee Laniers rotoscoping course for some great roto techniques.

[Luca Di Gioacchino]

You my get lucky with pulling a luma key on some parts of the subject.  You'll also have to do some good old-fashioned roto.  Just break it down into parts and start roto'ing.  Having said that, I once tested an AI plugin that works directly in Resolve which does all the roto work for you.  It's not perfect, but it helps.  If I remember the name I will post it here, but the man who created it is out of Australia.

 

[Rune Felix Holm]

You could consider outsourcing the rotoscoping to a company that specializes in roto and then do the rest yourself. Really good roto is really hard and takes years of practice.

[Luca Di Gioacchino]

Check out Resolve 17's Ai powered rotobrush.

 

[Rune Felix Holm]

The v17 roto module is impressive for what it promises to be in the future, but for now it is no more than a first attempt and I haven't been able to use its output for anything meaningful yet.

[Thomas Singh]

Hopefully, Resolves rotobrush improves over time but considering how poor the auto-roto solution in After Effects is after all these years I have no big hopes. Anyway, for now, see how much you can get away with using the luma keyers and then pick up the rest with manual roto.

[Bruno Mansi]

My vote would be to use Mocha Pro - available from Boris FX

It's a planar tracking tool that is used a lot for this sort of work.

It's available as a standalone version, but there's also plugin versions for OFX, Avid and Adobe After Effects.

I've used it lots in the past to solve roto work like this. Never used the OFX version,  but the standalone works well as does the AE version. I seem to remember there was a free, cut down version included in AE - don't know if this still is the case.

The latest version has added mesh warping tools - especially useful for cloth etc.

If you're using it under AE, I found a very useful add-on called Mocha Import +, which allowed you to work on stabilised precomps of your roto'ed  area. Great for working on those tricky areas where there's a bit of additional blur/touchup required.

 

 

Edited April 30, 2021 by Bruno Mansi

[Ross Shain]

Mocha AE is included free in After Effects and then yes, Mocha Pro OFX will run as a plugin inside Fusion. 

This video covers the basic roto with Mocha in Fusion workflow: https://borisfx.com/videos/quick-start-for-fusion-mocha-pro-5-ofx-plug-in/

and a PowerMesh tip for Fusion users: https://borisfx.com/videos/quick-tip-mocha-pro-s-powermesh-in-fusion/