[Bf-vfx] Plane Tracking naming

[David Jeske]

This tracking stuff is new, and I didn't write it, so take what I say here
with a grain of salt.. I may have mis-interpreted something..

On Mon, Aug 12, 2013 at 1:02 PM, Sean Kennedy <mack_dadd2 at hotmail.com>wrote:

>  I'd like to propose that the name of the new plane tracking tool be
> changed to something like Corner Pin, along with the plane deform node
> becoming something like Corner Pin Deform node.
>

That sounds like a good idea. Are there industry standard terms to refer to
the different types of corner-pinning modes? Such as blender's
Affine/Perspective/LocRotScale modes? Also, does "corner pin" imply a
single image patch track as it does in blender?


> (A single track set to Affine or Perspective actually tracks a plane. If
> we could then position the corner pin outline on a plane based of that
> single track, I would support calling that plane/planar tracking.)
>

What blender does with individual trackers seems really really different
than what mocha does with "planar tracking". That feature appears to be a
meta-tracking feature which automatically manages many individual tracks
within a planar surface. From this video on the mocha planar tracking..

http://www.youtube.com/watch?v=IjGsDMH2b5U

It looks like Mocha does (at least) two things I believe the current
Blender tracker does not do:

(a) the mocha "planar tracking spline" is not a tracker itself, but a
tracking region, within which mocha automatically establishes several
separate tracking chunk-patches -- think of each one of these patches like
a blender affine-tracker

(b) mocha tracks each  chunk motion (transformation, affine, skew,
perspective) as a holistic integration across all those patches -- knowing
they are part of planar object motion.

Using these methods gives it some accuracy benefits over what Blender can
do today... (1) it can solve and validate the motion of each chunk
constrained to the planar-motion derived from all chunks on the plane. (2)
if any one chunk becomes permanently or temporarily invalid (such as
because part of the planar content is changing) it can more easily reject
that chunk as not conforming to the plane, rather than causing tracking
error and drifting the individual chunk-track because of a mis-match.

The analogous operation in blender would be to manually set several Affine
or Perspective trackers across the plane (one for each chunk mocha
automatically establishes), and then establish some kind of
tracking-constraint across that set of trackers saying they should lie in a
plane (which blender can't do AFAIK).
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