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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

>  (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 J. Guelzow, PhD, FTICA
Concordia University College of Alberta

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