post by: Allar Kaasik
A couple of weeks ago I did a webinar on using Mocha Pro for clean-up and in particular, looking at advanced techniques in Nuke that use it beyond its original purpose of pure planar tracking.
Mocha, as you might now, is currently the best tool out there for doing planar-tracking fast and accurately. But the question is, can it handle non-planar surfaces like the curved wall of this tunnel?
The answer is: yes, it often tracks it much quicker much more accurately than any alternative point-tracker options. However, the track that you get out of it still a planar-track, so when you’re match-moving it, the non-planar curved areas will slide a tiny bit.
My trick is to use the CornerPins that you get out of Mocha to first stabilise the footage and to remove the perspective. This gives you a nice orthogonal view of the are that you want to patch. You can then fake some curvature onto it using whatever technique you want (e.g. Nuke’s GridWarp here)
Once your still image is ready, you can add the final curved motion onto it using Nuke’s SmartVectors, which do per-pixel match-move.
So, why not just use SmartVectors from the beginning? Yes, they’re great, but when match-moving over bigger spacial distances and perspective changes small tracking errors can accumulate and give you “warpy-wavy” looking results. Combining it with the Mocha Pro’s planar tracker allows you to remove the large motion and perspective really quickly and easily, making it easier for SmartVectors to “stay on track” (terrible pun..)
The point is, compositing is an art of problem-solving, so combining different tools and techniques is the way to get the best result.
Mocha Pro has a free trial and it works as a plugin in most of your favourite software packages, like Nuke, AfterEffects, Fusion, etc, in addition to the stand-alone option. The great thing is that once you’ve learnt it, the interface remains the same between the different packages, so if you know how to use it in Nuke, you’ll also know how to use it in Fusion. You can get free trial for Mocha from Boris FX website and if you’re a student, then you should check out their educational licensing option that gives you Mocha Pro, Sapphire, Continuum and Silhouette free for one year.
Also, check out the other half of that webinar recording to see how you could combine planar-tracking with camera-tracking to get more accurate results on roughly positioned geometry.