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Subject: RE: FW: [office-comment] Orientation problems with angles

• From: "Andreas J. Guelzow" <andreas.guelzow@concordia.ab.ca>
• To: <dennis.hamilton@acm.org>, <office-comment@lists.oasis-open.org>
• Date: Tue, 7 Aug 2012 14:01:31 -0600

```On Tue, 2012-08-07 at 13:16 -0600, Dennis E. Hamilton wrote:
> Implicit is really great for a specification, aye?

You are looking at a document page... What frame of reference were you
thinking of when we were approving the standard?
>
> In this implicit frame of reference, where is the origin around which the gradient-direction reference vector is dialed?

You do not need a specific center of rotation.

Why do you need a gradient-direction reference vector? You only need a
gradient-direction (in vector terms: one collection of all vectors that
are parallel to each other.)

So assuming that the 0 degree direction were specified you could pick
any arbitrary centre of rotation and you would end up wit the same
direction after rotation.

Andreas

>
>  - Dennis
>
> -----Original Message-----
> From: Andreas J. Guelzow [mailto:andreas.guelzow@concordia.ab.ca]
> Sent: Tuesday, August 07, 2012 09:30
> To: office-comment@lists.oasis-open.org
> Subject: RE: FW: [office-comment] Orientation problems with angles
>
> On Tue, 2012-08-07 at 10:07 -0600, Dennis E. Hamilton wrote:
> > I believe I can safely say that all vector characterizations on a
> > Cartesian plane are relative to a frame of reference.  Directions of
> > translation and rotation are relative to that frame of reference.
>
> Euclidean plane geometry predates cartesian coordinates. So clearly you
> can do plane geometry without a coordinate system. (Coordintate system
> in general just make it much easier.)
>
> >  (Clockwise is anti-clockwise when viewed from "behind", when viewed
> > in a mirror, etc.)
>
> In the situations at hand we know where the viewer is, so considering
> "viewed from behind" is really beside the point.
>
> >
> > Asking for identification of the axes and their directions for the
> > frame of reference is another way of nailing down what that frame of
> > reference is.  Then how that is projected onto the surface of the
> > document as presented to a viewer can be made precise.
>
> This only makes sense if you are assuming a multi (more than 2)-
> dimensional situation that is being projected. Again the situation at
> hand takes place on the 2-dimensional document plane with an implied
> frame of reference since this is a document an the plain english
> meanings of top, bottom, left, right and clockwise apply.
>
> >  Up, down, left, right, front, back, clockwise, etc., have no meaning
> > until there is agreement on what the frame of reference is.
>
> Note that ODF 1.2 does not give coordinate systems or any other frames
> of reference so clearly the plain english meaning of these terms has to
> appply.
>
> >  (There is a similar problem in ODF when certain characteristics are
> > dependent on the assumed writing direction and the relationship is
> > underspecified or ambiguously described.)
>
> Andreas
> >
>
>

--
Andreas J. Guelzow, PhD, FTICA
Concordia University College of Alberta
```

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