Libmv: Initial commit of unfinished AutoTrack API

This starts the creating the new AutoTrack API. The new API will
make it possible for libmv to do full autotracking, including
predictive tracking and also support multiple motion models (3D
planes etc).

The first goal (not in this patch) is to convert Blender to use
the new API without adding any new functionality.

This API currently contanins:

- Frame accessor to access frames which are stored in Blender side.
- New Tracks implementation
- New Reconstruction implementation

Currently this API only tested on doing the same frame-to-frame
tracking as the old API allowed to do. But it also supports now
predictive tracking which is based on the Kalman filter.

1 files changed, 362 insertions, 339 deletions

diff --git a/extern/libmv/ChangeLog b/extern/libmv/ChangeLog
index 276fbb2ff0d..5c2129b6b1a 100644
--- a/extern/libmv/ChangeLog
+++ b/extern/libmv/ChangeLog
@@ -1,3 +1,365 @@
+commit d976e034cdf74b34860e0632d7b29713f47c5756
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Sat Aug 23 00:38:01 2014 -0700
+
+    Minor keyframe selection cleanups
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D757
+
+commit bc99ca55dadfca89fde0f93764397c2fe028943d
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Sat Aug 23 01:55:32 2014 +0600
+
+    implement backward prediction
+    
+    The title actually says it all, just extend current implementation
+    of PredictMarkerPosition() to cases when tracking happens in the reverse
+    order (from the end frame to start).
+    
+    it's still doesn't solve all the ambiguity happening in the function
+    in cases when one tracks the feature and then re-tracks it in order
+    to refine the sliding. This is considered a separate TODO for now and
+    will likely be solved by passing tracking direction to the prediction
+    function.
+    
+    Reviewers: keir
+    
+    Reviewed By: keir
+    
+    Differential Revision: https://developer.blender.org/D663
+
+commit 5b87682d98df65ade02638bc6482d824cf0dd0b3
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu Aug 21 22:45:22 2014 -0700
+
+    Make libmv compile on Ubuntu 14.04
+    
+    Reviewers: fsiddi
+    
+    Reviewed By: fsiddi
+    
+    Subscribers: sergey
+    
+    Differential Revision: https://developer.blender.org/D755
+
+commit 0a81db623c458e0384b4f7060d1bcff8993fb469
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Wed Jul 23 00:42:00 2014 +0600
+
+    Fix wrong residual blocks counter
+    
+    This happened in cases when having zero-weighted tracks
+    and could lead to some assert failures on marking parameter
+    block constant.
+
+commit 2824dbac54cacf74828678be7a5c9fd960ce83e2
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Fri Jul 18 12:52:03 2014 +0600
+
+    Fix search area sliding issue
+    
+    The only way to do this is to store search region in floats
+    and round when we need to sample it. Otherwise you'll always
+    have sliding effect caused by rounding the issues, especially
+    when doing incremental offset (thing which happens in the
+    prediction code).
+    
+    Pretty much straightforward change apart from stuff to be kept
+    in mind: offset calculation int should happen relative to the
+    rounded search region. This is because tracker works in the space
+    of the search window image which get's rounded on the frame access,
+    
+    This makes API a bit creepy because frame accessor uses the same
+    Region struct as the search window in Marker and ideally we would
+    need to have either IntRegion or Region<int> in order to make
+    Libmv fully track on what's getting rounded and when.
+    
+    Reviewers: keir
+    
+    Reviewed By: keir
+    
+    Differential Revision: https://developer.blender.org/D616
+
+commit 04862c479332308be47a0f27361402444ace8880
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Fri May 9 23:00:03 2014 +0200
+
+    Start the automatic 2D tracking code
+    
+    This starts the 2D automatic tracking code. It is totally unfinished.
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D523
+
+commit be679f67d807a2139c1f7d7e2ca45141940b30d5
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Fri May 9 14:36:04 2014 +0200
+
+    Also shift the search window
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D520
+
+commit 66b8f5eef2633ebcde32a388fc14c60171011821
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Fri May 9 13:06:28 2014 +0200
+
+    Change the search region to absolute frame coordinates
+    
+    Smarter Eigen usage
+    
+    Better error logging
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D519
+
+commit a08193319ae409fad8f08887eae1f79f02e91eaa
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Fri May 9 12:02:47 2014 +0200
+
+    First cut at predictive tracing
+    
+    This adds a Kalman filter-based approach to predict where a marker
+    will go in the next frame to track. Hopefully this will make the
+    tracker work faster by avoiding lengthy searches. This code
+    compiles, but is otherwise untested, and likely does not work.
+    
+    Fix else branch
+    
+    Add some tests
+    
+    Update patch coordinates as well (and test)
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D518
+
+commit 607ffb2f62b56e34a841abbb952d83e19cd1e23c
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu May 8 16:05:28 2014 +0200
+
+    Add constructor to AutoTrack
+
+commit c39e20a0c27da3733804c3848454b5d4c4f0e66b
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu May 8 16:04:20 2014 +0200
+
+    Fix GetMarker compilation issue
+
+commit 8dd93e431b6e44439c803bfd26ec2669b656177e
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu May 8 15:50:26 2014 +0200
+
+    Expose GetMarker() in AutoTrack
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D516
+
+commit 4405dff60ea08d454b64da1a7c0595d9328cf8a3
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu May 8 15:38:14 2014 +0200
+
+    Add public SetMarkers to AutoTrack
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D515
+
+commit c90837f6db276a3b1f610eaad509155f6a43b24f
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Thu May 8 15:17:48 2014 +0200
+
+    Make autotrack skeleton compile
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D514
+
+commit be01baa2e82e36f63e548f073157e68d2ff870c0
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Wed May 7 18:48:55 2014 +0200
+
+    Add preliminary TrackMarkerToFrame in autotrack
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D509
+
+commit 0cab028d591b3d08672ca86eb6c6e4ac1aacf1d0
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Wed May 7 17:59:11 2014 +0200
+
+    Remove assert from ArrayND Resize
+    
+    That assert broke initialization of arrays which doesn't
+    own the data since constructor uses Resize to set shape
+    and strides.
+    
+    Strides are still to be fixed, but that's for later.
+
+commit 64f9c118029a9351e9023e96527c120e1d724d5b
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Wed May 7 17:42:21 2014 +0200
+
+    Fix ArrayND freeing the data it doesn't own
+    
+    Can't really guarantee it works fully correct now,
+    but at least this check is needed anyway and compilation
+    works just fine.
+    
+    Reviewers: keir
+    
+    Reviewed By: keir
+    
+    Differential Revision: https://developer.blender.org/D508
+
+commit 0618f1c8e88dfc738cdde55784da80b889905e7c
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Wed May 7 12:03:32 2014 +0200
+
+    Minor changes
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D505
+
+commit 5c34335e1bb90c4ed701ee830c718ed4e20dbffa
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Wed May 7 11:12:23 2014 +0200
+
+    Fix compilation error in frame accessor
+    
+    - int64 is not a standard type, we've got int64_t defined in
+      std int. We also have an msvc port of this header, so should
+      not be an issue.
+    
+    - Fixed inconsistency in usage of CacheKey and Key, used Key.
+    
+    - Some functions weren't marked as virtual.
+    
+    Additional change: added self to authors.
+    
+    Reviewers: keir
+    
+    Reviewed By: keir
+    
+    Differential Revision: https://developer.blender.org/D504
+
+commit 06bc207614e262cd688e2c3ed820ade7c77bdb66
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Tue May 6 22:30:59 2014 +0200
+
+    Start new Tracks implementation
+    
+    This adds the new Tracks implementation, as well as a
+    trivial test to show it compiles.
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D502
+
+commit 25ce061e6da69881460ba7718bb0d660a2380a02
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Tue May 6 19:10:51 2014 +0200
+
+    Add Reconstruction class for new API
+    
+    This starts the new Reconstruction class (with support for e.g. planes). This
+    also starts the new namespace "mv" which will eventually have all the symbols
+    we wish to export.
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D501
+
+commit 0a6af3e29016048978aea607673340500e050339
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Tue May 6 17:52:53 2014 +0200
+
+    Add a new Tracks implementation
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D500
+
+commit 887b68d29c2b198f4939f9ab5153881aa2c1806e
+Author: Keir Mierle <mierle@gmail.com>
+Date:   Tue May 6 17:01:39 2014 +0200
+
+    Initial commit of unfinished AutoTrack API
+    
+    This starts the creating the new AutoTrack API. The new API will
+    make it possible for libmv to do full autotracking, including
+    predictive tracking and also support multiple motion models (3D
+    planes etc).
+    
+    The first goal (not in this patch) is to convert Blender to use
+    the new API without adding any new functionality.
+    
+    Note: This does not add any of the API to the build system!
+    It likely does not compile.
+    
+    Reviewers: sergey
+    
+    Reviewed By: sergey
+    
+    Differential Revision: https://developer.blender.org/D499
+
+commit 08cc227d431d257d27f300fbb8e6991e663302da
+Author: Sergey Sharybin <sergey.vfx@gmail.com>
+Date:   Tue May 6 13:09:22 2014 +0200
+
+    Fix homography test failure
+    
+    It was caused by assuming that reconstructed homography matrix
+    should look exactly the same as the matrix used to generate a
+    test case.
+    
+    It's not actually valid assumption because different-looking
+    matrices could correspond to the same exact transform.
+    
+    In this change we make it so actual "re-projected" vectors
+    are being checked, not the values in matrix. This makes it
+    more predictable verification.
+    
+    Reviewers: keir
+    
+    Reviewed By: keir
+    
+    Differential Revision: https://developer.blender.org/D488
+
 commit 0b7d83dc9627447dc7df64d7e3a468aefe9ddc13
 Author: Sergey Sharybin <sergey.vfx@gmail.com>
 Date:   Wed Apr 23 19:14:55 2014 +0600
@@ -338,342 +700,3 @@ Date:   Thu Feb 13 23:55:03 2014 +0600
     
     Actually we're to switch to external Ceres rather than
     bundled one, would make life much easier actually.
-
-commit b1381540305d69c702eb2f051bd543fb5c1c3e2c
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Thu Feb 6 18:01:58 2014 +0600
-
-    Made FAST detector optional
-    
-    This way it's possible to bundle Libmv sources subset
-    to applications which doesn't need FAST detector.
-    
-    Mainly this is done for Blender integration.
-
-commit da4607f010bca0b3532cd4444afbb10bc774fc32
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Jan 28 18:32:39 2014 +0600
-
-    Implemented scoped_array and use it in detector
-    
-    scoped_array is pretty much the same as scoped_ptr
-    with the only difference that it'll free memory using
-    delete[] operator.
-    
-    It also gives some additional API functions to access
-    array elements.
-    
-    Currently it only used to manage images denoted as byte
-    arrays in detector.
-    
-    Reviewers: keir
-    
-    Reviewed By: keir
-    
-    Differential Revision: https://developer.blender.org/D266
-
-commit cd7eb3eff2e69ce5e08570ead83ae6d35ee48857
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Jan 28 17:23:47 2014 +0600
-
-    Improvements to weighted tracks behavior
-    
-    First thing changed by this commit is making it so
-    Euclidean intersection takes track weight into account
-    when solving minimization problem. This behaves the
-    same exact way as it is for BA step.
-    
-    Second thing is related on how average reprojection error
-    is being calculated. It didn't take track weight into
-    account which could confuse users. Now average reprojection
-    error will give the same result as intersection/BA uses
-    during minimization which gives much more predictable
-    behavior.
-    
-    Reviewers: keir
-    
-    Reviewed By: keir
-    
-    CC: sebastian_k
-    
-    Differential Revision: https://developer.blender.org/D265
-
-commit 6559b36dc14369175bfa0830323146acd3426483
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Jan 28 16:39:14 2014 +0600
-
-    Fixes for keyframe selection
-    
-    Using tracks with constant zero weight used to crash
-    keyframe selection since it was trying to use missing
-    parameter blocks for Jacobian evaluation,
-    
-    Also fixed possible issues with wrong camera block being
-    marked as variable. This could technically happen when
-    having zero weighted tracks. Made it so all camera blocks
-    are marked as variable for now.
-
-commit 557d531b061aa69d114e89cbb325c5175389afec
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Jan 28 16:10:33 2014 +0600
-
-    Style cleanup: wrong indentation of wrapped line
-
-commit ca15262cf07a873268173965ee1fb84f9729b744
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Jan 28 15:21:36 2014 +0600
-
-    Rework detector API and implement Harris detector
-    
-    Switch the detector API to a single function which accepts
-    a float image and detector options. This makes usage of
-    feature detection more unified across different algorithms.
-    
-    Options structure is pretty much straightforward and contains
-    detector to be used and all the detector-specific settings.
-    
-    Also implemented Harris feature detection algorithm which
-    is not as fast as FAST one but is expected to detect more
-    robust feature points.
-    
-    Reviewers: keir
-    
-    Reviewed By: keir
-    
-    Differential Revision: https://developer.blender.org/D258
-
-commit 6458915f64fceba108c5279b7320ca8c76e8a742
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Fri Jan 24 19:14:18 2014 +0600
-
-    Add arcanist configuration file
-
-commit 0a69fadadc5aacbd339f839ac5bd12c3571278b1
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Thu Jan 9 15:50:11 2014 +0600
-
-    Fix compilation error on NetBSD
-    
-    - NetBSD doesn't provide sincos(3) in libm, so don't try to use it
-    - Use posix_memalign on NetBSD
-    
-    Original patch is by Jeorg Sonnenberger to Blender patch tracker, thanks!
-
-commit b0df3e291e6c85f791658be04334efafc41989f5
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Thu Jan 2 15:12:18 2014 +0600
-
-    Fix build configuration warnings
-    
-    Those warnings were mainly caused by installation
-    configuration of Ceres. Made some tweaks to make
-    CMake happy for now.
-    
-    But for sure bigger cleanup here is needed.
-
-commit b68de6acd20f3ffab92e0cd450198a700cd109ab
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Thu Jan 2 15:04:05 2014 +0600
-
-    Code and style cleanup
-    
-    Mainly fixed some style warnings reported by cpplint.
-    
-    Also changed how camera (un)distortion happens internally
-    by replacing number of channels as a template argument
-    with number as channels passing as function argument.
-    Makes code easier to follow by eliminating loads checks
-    how much channels are used and which argument to pass to
-    the template.
-
-commit b9e467e7c077b58199c4110f6967b7c18d1e7bf7
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 20:34:39 2013 +0600
-
-    Update Ceres to the latest upstream
-    
-    This brings up much easier termination type usage,
-    which for us means we might use:
-    
-      ceres::Summary::IsSolutionUsable()
-    
-    instead of doing manual funky enum values check.
-
-commit 3aeb2367e50b52ca2b9d59d4f0f0b4bbfd6a05e8
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 20:43:24 2013 +0600
-
-    Update gtest to latest version 1.7.0
-    
-    Also reshuffled CMakeLists in order to avoid
-    conflicts happening between gflags bundled to
-    Ceres and third_party.
-
-commit 30aaa9cd0b4a4eb0948a17824e7e7622d8ebcb41
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 20:10:06 2013 +0600
-
-    Changes for VC2013
-    
-    Solves compilation error when using msvc2013
-    
-    Original patch is by Alexandr Kuznetsov to blender.git
-
-commit b204c0d25065a2b149de256929ff37d8f00f45bb
-Author: Keir Mierle <mierle@gmail.com>
-Date:   Tue Dec 31 20:05:58 2013 +0600
-
-    Eagerly attempt to refine a track before doing a brute search
-    
-    Before the refinement phase of tracking, a brute force SAD search
-    is run across the search area. This works well but is slow;
-    especially if the guess for the track's location is accurate.
-    
-    This patch runs a refinement phase before running a brute force
-    search, hoping that the guessed position (in x2, y2) is close to
-    the best answer. If it is, then no brute search is done. If it is
-    not, then a normal brute force search followed by refinement is
-    done.
-    
-    In some cases this may produce worse tracks than before; the
-    regressions will need investigation. The predictive motion model
-    (to be implemented) will reduce the probability of that happening.
-
-commit 5361513f0328ff94b53125d29129561bb03132e8
-Author: Keir Mierle <mierle@gmail.com>
-Date:   Tue Dec 31 20:04:46 2013 +0600
-
-    Fix bug where libmv tracking incorrectly succeeds on failure
-    
-    Before this patch, if Ceres returned USER_SUCCESS indicating that
-    Ceres was only changing the tracked quad slightly between
-    iterations (indicating convergence), no final correlation check
-    was done. This leads to incorrectly returning that the tracking
-    was successful, when it actually failed.
-
-commit ba9e63eed09e33a48bbcb081058f45ac16f8738e
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 20:00:46 2013 +0600
-
-    Implementation of weighted tracks
-    
-    Added a weight field to Track structure which means
-    how much affect this track will have on the final
-    reconstruction.
-    
-    Currently it affects on BA step only which in most
-    cases will work just fine. However, it worth looking
-    into weight support for intersection/resection.
-
-commit 4600df8b685ca8c4daa22d6c3b0125fd42c3bc67
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 19:30:14 2013 +0600
-
-    Code cleanup: move function prototype to header file
-
-commit 0ce5b6efde774b3f042acf9e42c95674548f1c01
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 19:26:48 2013 +0600
-
-    Get rid of Allow Fallback option for euclidean resection
-    
-    It was rather confusing from the user usage point of view
-    and didn't get so much improvement after new bundle adjuster
-    was added.
-    
-    In the future we might want to switch resection to PPnP algorithm,
-    which could also might be a nice alternative to fallback option.
-
-commit 5d063426f4809000c27f38ed798e4224bbd09a6d
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 19:24:05 2013 +0600
-
-    Use explicit declaration of int types sign
-    
-    Mainly needs to make blender happy with this custom
-    header which used to run into conflict with other int
-    types headers.
-    
-    Wouldn't harm being more explicit here anyway.
-
-commit c5be59dee94f94de369006c544080282cfb245cc
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Tue Dec 31 14:50:00 2013 +0600
-
-    Implement refinement of estimated homography/fundamental matrices
-    
-    It was only possible to perform algebraic estimation, which didn't
-    give so much accurate results.
-    
-    Implemented a way to perform algebraic estimation followed with
-    refinement step using Ceres minimizer.
-    
-    The code was actually mostly already there since keyframe selection
-    patch. Made such estimation a generic function in multiview/ and
-    hanged API for estimation in order to pass all additional options via
-    an options structure (the same way as it's done fr Ceres).
-    
-    Most of the options are straight-forward to understand,but some
-    deserves more description here:
-    
-    * expected_average_symmetric_distance is used as an early output check
-      and as soon as average symmetric error goes below this threshold
-      refining finishes.
-    
-      This distance is measured in the same units as input points are.
-    
-      It is arguable whether we need callback for this or not, but seems
-      Ceres doesn't have some kind of absolute threshold for function value
-      and function_tolerance behaves different from logic behind expected
-      symmetric error.
-    
-    * There' an option to normalize correspondences before estimating the
-      homography in order to increase estimation stability. See
-    
-        R. Hartley and A. Zisserman. Multiple View Geometry in Computer
-        Vision. Cambridge University Press, second edition, 2003.
-    
-        https://www.cs.ubc.ca/grads/resources/thesis/May09/Dubrofsky_Elan.pdf
-
-commit 1cdad972c4a9005e78891524cbd6d65600ca7e99
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Wed Sep 25 16:12:29 2013 +0600
-
-    Code cleanup: Minor function capitalization fix
-    
-    Original patch by Joseph Mansfield to the Blender repository.
-
-commit 434316d084e8a41fd452f03610d7244d664948dc
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Wed Sep 25 16:07:43 2013 +0600
-
-    Code cleanup: spelling correction
-    
-    Original patch by Joseph Mansfield to the Blender repository.
-
-commit 5cfe8465ac70407c0959c53bcd5206657a1322a2
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Wed Sep 25 16:02:48 2013 +0600
-
-    Fix for uninitialized covariance matrix
-    
-    Lead to unpredictable tracking termination criteria.
-
-commit fd86b77d413489649a989f075b061714ed9a72fc
-Author: Sergey Sharybin <sergey.vfx@gmail.com>
-Date:   Wed Sep 25 16:01:19 2013 +0600
-
-    Add Procrustes PNP ("PPnP") resection algorithm to libmv
-    
-    This adds a new Euclidean resection method, used to create the
-    initial reconstruction in the motion tracker, to libmv. The method
-    is based on the Procrustes PNP algorithm (aka "PPnP"). Currently
-    the algorithm is not connected with the motion tracker, but it
-    will be eventually since it supports initialization.
-    
-    Having an initial guess when doing resection is important for
-    ambiguous cases where potentially the user could offer extra
-    guidance to the solver, in the form of "this point is in front of
-    that point".
-    
-    Original patch by Keir Mierle made to Blender repository.