Transf WD Euler transformation

[Laurent MICHEL]

Hello,

I do not practice Euler transformations daily, but according to my 
college souvenirs, that is by definition a 3D rotation with a well 
defined sequence of rotation axis.
In my understanding, the Euler rotation is even not a particular case of 
the Transf rotation since the 3 Euler rotations are not about native 
axis as stated in the definition you give.

> Defines a rotation operation in a 3-dimensional cartesian coordinate space, defined as a series of rotations about the native axes (x,y,z)

If I'm right, the class should be renamed (RotationSequence ?). If not, 
my comment is no longer relevant.

Laurent

Le 02/04/2020 à 16:40, CresitelloDittmar, Mark a écrit :
> Laurent,
> 
> This came directly from the implementation group discussions back in Dec 
> 2018.
> gWCS has use cases where more than 3 rotations are useful, for example 
> EulerRotation(angles=[12, 1, 2, 3], axes=‘xyzx’).
> So we've taken this approach of having a sequence of EulerAngles which 
> specify the 'axis of rotation' (of the 3D space as either 'x', 'y', or 
> 'z') and angle.
> 
> Mark
> 
> 
> On Thu, Apr 2, 2020 at 8:31 AM Laurent MICHEL 
> <laurent.michel at astro.unistra.fr 
> <mailto:laurent.michel at astro.unistra.fr>> wrote:
> 
>     Dear,
> 
>     My comment #1: Why is the Euler Transformation class so complex?
> 
>     - It is always a 3D transformation, this there is no reason to setup a
>     1-* aggregation with angles.
> 
>     - Euler angles (nutation, rotation, intrinsic rotation) are well
>     defined, there is no need for a specific datatype (EulerAngle). So we
>     could just have 3 class attributes.
> 
>     - Using a specific datatype where angles are identified by a the
>     name of
>     the rotation axis supposes we have a vocabulary for this, which is a
>     bit
>     complicated for this purpose with the risk a implementation errors.
> 
>     Take care of yourself.
> 
>     LM
> 
>     -- 
>     ---- Laurent MICHEL              Tel  (33 0) 3 68 85 24 37
>            Observatoire de Strasbourg  Fax  (33 0) 3 68 85 24 32
>            11 Rue de l'Universite      Mail
>     laurent.michel at astro.unistra.fr <mailto:laurent.michel at astro.unistra.fr>
>            67000 Strasbourg (France)   Web http://astro.u-strasbg.fr/~michel
>     ---
> 

-- 
---- Laurent MICHEL              Tel  (33 0) 3 68 85 24 37
      Observatoire de Strasbourg  Fax  (33 0) 3 68 85 24 32
      11 Rue de l'Universite      Mail laurent.michel at astro.unistra.fr
      67000 Strasbourg (France)   Web  http://astro.u-strasbg.fr/~michel
---