Kalman filter prototype

This PR is an early preview of Kalman filtering to 6D tag pose. Comes with hardcore c++11 `std::map::emplace()` and related syntax :)

Is a partial solution to #19.

For now, the quick & dirty covariance calibration seems to work decent enough. Please test further.

~~A huge issue now is gimbal lock and discontinuities in angle. We need quaternions to fix this.~~ done

In the near future, more goodies such as 

- ~~Calibration API~~ done
- ~~Enable/disable on demand API~~ done
- ~~Quaternions~~ done
- ~~IMU integration~~ done, see also https://github.com/chili-epfl/qml-imu
- ~~Optimizations~~ pretty much done
- ~~Sample~~ done
- ~~Remove `Filter` completely~~ done
- ~~Add tag discard mechanism~~ done
- ~~Fully document all math involved~~ done

will follow. 
cool stuff :))))
so many good memories.

2014-12-19 13:58 GMT+01:00 Ayberk Özgür <notifications@github.com>:
>
> In include/chilitags.hpp
> <https://github.com/chili-epfl/chilitags/pull/75#discussion-diff-22103161>
> :
>
> > @@ -424,8 +383,18 @@ Chilitags &getChilitags();
> >          0 ,   0 ,   0 ,  1 }
> >      \endverbatim
> >      \param tags a list of tags, as returned by Chilitags::find().
> > +
> > +    \param camDeltaR Rotation from the previous camera frame to
> > +    the current camera frame, i.e rotation of the current camera frame in the
> > +    last camera frame. Quaternion format (scalar, vx, vy, vz).
> > +
> > +    \param camDeltaX Translation from the previous camera frame
> > +    to the current camera frame, i.e position of the current camera frame in
> > +    the last camera frame.
> >   */
>
> IMU works with quaternions because it comes directly from the state. There
> is no 4x4 transform matrix at any stage.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/chili-epfl/chilitags/pull/75/files#r22103161>.
>