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