<div dir="ltr">Hopefully, the gWCS folks can respond to this more fully.<div>It was added in support of their implementation, which I mapped to EulerAngleRotation. However, looking at <a href="https://docs.astropy.org/en/stable/api/astropy.modeling.rotations.EulerAngleRotation.html">that spec</a>, it appears to support only 3 rotations.</div><div><br></div><div>Mark</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Apr 3, 2020 at 9:11 AM Laurent MICHEL <<a href="mailto:laurent.michel@astro.unistra.fr">laurent.michel@astro.unistra.fr</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Hello,<br>
<br>
I do not practice Euler transformations daily, but according to my <br>
college souvenirs, that is by definition a 3D rotation with a well <br>
defined sequence of rotation axis.<br>
In my understanding, the Euler rotation is even not a particular case of <br>
the Transf rotation since the 3 Euler rotations are not about native <br>
axis as stated in the definition you give.<br>
<br>
> Defines a rotation operation in a 3-dimensional cartesian coordinate space, defined as a series of rotations about the native axes (x,y,z)<br>
<br>
If I'm right, the class should be renamed (RotationSequence ?). If not, <br>
my comment is no longer relevant.<br>
<br>
Laurent<br>
<br>
Le 02/04/2020 à 16:40, CresitelloDittmar, Mark a écrit :<br>
> Laurent,<br>
> <br>
> This came directly from the implementation group discussions back in Dec <br>
> 2018.<br>
> gWCS has use cases where more than 3 rotations are useful, for example <br>
> EulerRotation(angles=[12, 1, 2, 3], axes=‘xyzx’).<br>
> So we've taken this approach of having a sequence of EulerAngles which <br>
> specify the 'axis of rotation' (of the 3D space as either 'x', 'y', or <br>
> 'z') and angle.<br>
> <br>
> Mark<br>
> <br>
> <br>
> On Thu, Apr 2, 2020 at 8:31 AM Laurent MICHEL <br>
> <<a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a> <br>
> <mailto:<a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a>>> wrote:<br>
> <br>
> Dear,<br>
> <br>
> My comment #1: Why is the Euler Transformation class so complex?<br>
> <br>
> - It is always a 3D transformation, this there is no reason to setup a<br>
> 1-* aggregation with angles.<br>
> <br>
> - Euler angles (nutation, rotation, intrinsic rotation) are well<br>
> defined, there is no need for a specific datatype (EulerAngle). So we<br>
> could just have 3 class attributes.<br>
> <br>
> - Using a specific datatype where angles are identified by a the<br>
> name of<br>
> the rotation axis supposes we have a vocabulary for this, which is a<br>
> bit<br>
> complicated for this purpose with the risk a implementation errors.<br>
> <br>
> Take care of yourself.<br>
> <br>
> LM<br>
> <br>
> -- <br>
> ---- Laurent MICHEL Tel (33 0) 3 68 85 24 37<br>
> Observatoire de Strasbourg Fax (33 0) 3 68 85 24 32<br>
> 11 Rue de l'Universite Mail<br>
> <a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a> <mailto:<a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a>><br>
> 67000 Strasbourg (France) Web <a href="http://astro.u-strasbg.fr/~michel" rel="noreferrer" target="_blank">http://astro.u-strasbg.fr/~michel</a><br>
> ---<br>
> <br>
<br>
-- <br>
---- Laurent MICHEL Tel (33 0) 3 68 85 24 37<br>
Observatoire de Strasbourg Fax (33 0) 3 68 85 24 32<br>
11 Rue de l'Universite Mail <a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a><br>
67000 Strasbourg (France) Web <a href="http://astro.u-strasbg.fr/~michel" rel="noreferrer" target="_blank">http://astro.u-strasbg.fr/~michel</a><br>
---<br>
</blockquote></div>