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From: Hubert.Holin_at_[hidden]
Date: 2000-12-21 17:26:07

Paris (U.E.), le 21/12/2000

        Actually, the file I uploaded is one end product of soome work I
did with a colleague about orientation interpolation (quaternions are
superior to Euler angles, among other reasons because they are not
succeptible to "gimbal lock", which is a degeneracy in the
representation for special values of the orientation).

        The problem we solved (though this is *not* included in the public
file), is that of orientation under constraint, i.e. if we want to
emulate a real film camera, the "up" must not "wobble" between
keyframes. I tried to licence that part, so far with no result :-< .

        One thing which *is* in that file is the exponential of the
quaternions, which I believe, is a result which I invented (more
precisely, the closed formula giving the result is my invention, not
the existence of the exponential (of one stripe or another) on the
quaternions...). This can be used to achieve interpolation of
orientations (in 3d-space), but with the "woble"...

        A last note: I have some ideas about cryptography and quaternions,
but the implementation I proposed is not the best suited to this

                Hubert Holin

--- In boost_at_[hidden], Lutz Kettner <kettner_at_i...> wrote:
> Hi,
> there is interest in the graphics community for quaternions as
> a _good_ representation of 3d rotations and for the ArcBall user
> interface interaction technique for rotations. They are also very
> nice for interpolating between two different orienations of a
> 3d object. I don't know about numerics and quaternions.
> Lutz Kettner
> ----------------------------------------------------------------------
> UNC Computer Science email: kettner_at_c...
> CB 3175, Sitterson Hall phone: (919) 962-1700 x7759
> Chapel Hill, NC 27599-3175, USA fax: (919) 962-1799
> ---------------------------------------------------------------------

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