[Bf-vfx] Plane Tracking naming

[Sean Kennedy]

New tools put into the tomato branch last week by Keir and Sergey.The tool is called Plane Track. It's pretty awesome!
Sebastian's quick demohttps://vimeo.com/71727578
Keir's more in-depth demohttp://www.youtube.com/watch?v=vISEwqNHqe4

From: davidj at gmail.com
Date: Mon, 12 Aug 2013 19:33:09 -0700
To: bf-vfx at blender.org
Subject: Re: [Bf-vfx] Plane Tracking naming



And no, corner pin simply implies a rectangular image is being deformed to fit into a defined rectangular patch that has been tracked into live footage using multiple tracks.



Given that, what feature in blender are you asking to rename corner-pinning? 



The single track perspective stuff Blender is doing when you set a tracker to use Affine or Perspective is actually planar tracking as generally accepted by the vfx community. However, there is no way to actually apply that planar data as a corner pin on it's own. That planar tracking is happening ONLY for the purpose of locking the individual track to it's pattern better.


Right, my limited understanding is that the current tracker can't constrain multiple tracks to a plane, so the closest you could get to a "corner-pinned rectangular image" is tracking 3-4 points, and then either mapping a 3d triangle to the 3 points, or a quad to the four points. 


If we could put one tracker into the shot, set it to Perspective, track a plane, and then use the new corner pin tools on THAT plane, that would be planar tracking as the vfx industry understands it.


Except this isn't at all what you want to do, because you want the tracked plane to have it's error minimized over all perspective trackers on the plane.. not driven by a single-tracker's quasi-accurate perspective track.

 Yes, in Mocha, you don't place actual trackers, it recognizes the entire feature inside the mask you create. It works as you describe, ignoring sections that become obscured or move out of frame.

 

In the example in that video, they draw a big mask around the screen, track it, then set up a corner pin on it, which magically sticks to the "plane" it just tracked. You cannot do that in Blender currently. You would have to track each corner of the phone, then place your corner pin box on the plane defined by those tracks. That is corner pinning.


..which BTW, sounds really nice..  

And actually, Blender is sort of in-progress with actually being able to do exactly what Mocha does. The Ceres library is already integrated, and planar recognition is being used to make individual point tracks more accurate (that's the Affine and Perspective modes). 


Scroll down to the "Planar Tracking" sectionhttp://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.64/Motion_Tracker


But planar tracking is NOT yet being used the way it is in Mocha, to define an actual plane which you can then use to attach images to. It's strictly being used for more accurate point tracks.


When those tools do eventually work, those are the tools that should be called "planar". Pinning a plane to multiple point tracks is simple good corner pinning.


What tools are being called planar now? I'm not aware of any. That blender demo video had some casual uses of the term "planar" but AFAIK there is no such named feature in Blender. Am I wrong about this? Or are you simply objecting to terminology used in a demo video?




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