[MEI-L] Coordinate system confusion [and terminology]

Fri Jul 7 20:58:28 CEST 2017

> We can/should define a "vu" in relation to diatonic steps though.

Is that not already the case? Otherwise, I am confused...  In other words
1vu = 1 diatonic step (such as E to F, or G-flat to A-sharp since the
chromatic alteration does not matter).

On 7 July 2017 at 20:45, Roland, Perry D. (pdr4h) <
pdr4h at eservices.virginia.edu> wrote:

>
> I have trouble, as I think most folks would, with values like "2-1/2
> half-spaces". I can live with "2-1/2 steps", but still prefer "2-1/2 vu".
> We can/should define a "vu" in relation to diatonic steps though.
>
> --
> p.
>
>
> > -----Original Message-----
> > From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf Of
> Byrd, Donald A.
> > Sent: Friday, July 07, 2017 11:23 AM
> > To: Music Encoding Initiative <mei-l at lists.uni-paderborn.de>
> > Subject: Re: [MEI-L] Coordinate system confusion [and terminology]
> >
> > Sure. As I said, both Gould and Ross talk about "half spaces".  --DAB
> >
> > On Jul 7, 2017, at 11:03 AM, "Roland, Perry D. (pdr4h)" <
> pdr4h at eservices.virginia.edu>
> >  wrote:
> >
> > >
> > > Hi Don,
> > >
> > > You make a good argument for the term "staff-space" or "space".
> However, MEI doesn't
> > use this distance as its unit of measurement. Instead, MEI uses *half
> the distance* between
> > adjacent staff lines, hence the need for a different term.  Perhaps
> "interline distance" and
> > "virtual unit" aren't intuitive, but they accurately describe the
> situation, which "staff-space"
> > or "space" do not.  Of course, we could start using the entire distance
> between staff lines
> > as the unit, but that would mean changing all existing MEI markup and
> software.
> > >
> > > --
> > > p.
> > >
> > >
> > >> -----Original Message-----
> > >> From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf
> Of Byrd, Donald
> > A.
> > >> Sent: Tuesday, July 04, 2017 11:26 AM
> > >> To: Music Encoding Initiative <mei-l at lists.uni-paderborn.de>
> > >> Subject: Re: [MEI-L] Coordinate system confusion [and terminology]
> > >>
> > >> This reminds me of another source of coordinate system confusion,
> > >> namely the term for the distance between staff lines. Verovio source
> > >> code calls it a "double unit", and half that distance a "virtual
> unit" or "VU" or just
> > "unit"; none of those terms is at all intuitive.
> > >> Johannes calls it the "interline distance", which is much better, but
> > >> rather long, and "half interline distance" is way too long (and
> > >> clumsy). Well, look at Chapter 1 of _Behind Bars_. Her term is
> > >> "stave-space", or just "space" for short; half that distance, of
> > >> course, is a "half space". Ross' _Art of Music Engraving and
> > >> Processing_, the only other book I know of that says much on the
> subject, just uses the
> > term "space'. So, for example, both might describe a certain stem length
> as "2-1/2 spaces".
> > >>
> > >> I submit "stave-space" (or "staff-space" on my side of the Puddle) as
> > >> the full term and "space" for short are both the most standard and
> the best terms.
> > >>
> > >> --Don
> > >>
> > >>
> > >> On Jul 4, 2017, at 11:16 AM, Daniel Alles
> > >> <DanielAlles at stud.uni-frankfurt.de>
> > >> wrote:
> > >>
> > >>> Thank you, Johannes, that really helped and made that clear. So I
> > >>> can continue using the
> > >> Edirom-coordinates for ulx etc.
> > >>>
> > >>>
> > >>>
> > >>> Zitat von Johannes Kepper <kepper at edirom.de>:
> > >>>
> > >>>> Dear Daniel,
> > >>>>
> > >>>> that's a real confusion, and we need to make it clearer in the
> > >>>> guidelines. *Pixel* coordinates are always with the origin in the
> > >>>> top left corner. *Music* coordinates, however, are always bottom
> > >>>> up. @ulx and so on are always in pixel units, but @vo (vertical
> > >>>> offset) is specified in interline distances (half the distance
> > >>>> between two staff lines, or, in other words, the vertical distance
> > >>>> between a C4 and a D4, or any other two adjacent notes). If you
> > >>>> want to specify that a dynamic is written above its default
> > >>>> position, it seems more natural that values go up (i.e., @vo="3").
> > >>>> This means that for musical units the origin has to be bottom left.
> > >>>> I know it's confusing in the guidelines, and we will address this
> > >>>> at some point. If you don't mind, you're invited to prepare
> > >>>> something on Git and submit a pull request ;-)
> > >>>>
> > >>>> Hope this helps,
> > >>>> jo
> > >>>>
> > >>>>
> > >>>>> Am 04.07.2017 um 14:48 schrieb Daniel Alles <DanielAlles at stud.uni-
> > frankfurt.de>:
> > >>>>>
> > >>>>> Dear all,
> > >>>>>
> > >>>>> at the moment, I am a little bit confused about how MEI defines
> its coordinate
> > system:
> > >> It is possible to add the attributes @ulx, @uly, @lrx and @lry to for
> > >> example a surface, as written in part 12 of the Guidelines, which
> > >> places the origin of the coordinate system in the upper left corner.
> All the examples in
> > that part show that behavior, ulx/uly is always 0/0.
> > >> This would correspond to the coordinate systems used in SVG and DOM
> > >> and (which is what I use for my work) Edirom Editor. On the other
> > >> hand it is written in part 22.3, that MEI uses a coordinate system in
> > >> which "the y-axis points from bottom up". That would mean, that
> ulx/uly could never
> > be 0/0.
> > >>>>>
> > >>>>> So now my questions: Is it sufficient to use the coordinates like
> > >>>>> in the examples, with
> > >> the origin in the upper left corner? Would that "override" MEIs
> original coordinate
> > system?
> > >> If not: Isn't the possibility to encode areas from top-left to
> > >> bottom-right corners a semantic error in MEI, if the coordinate
> system is pointing from
> > bottom-left to top-right?
> > >>>>>
> > >>>>> Best,
> > >>>>> Daniel
> > >>>>>
> > >>>>>
> > >>>
> > >>>
> > >>>
> > >>> _______________________________________________
> > >>> mei-l mailing list
> > >>> mei-l at lists.uni-paderborn.de
> > >>> https://lists.uni-paderborn.de/mailman/listinfo/mei-l
> > >>
> > >> ---
> > >> Donald Byrd
> > >> Woodrow Wilson Indiana Teaching Fellow Adjunct Associate Professor of
> > >> Informatics Visiting Scientist, Research Technologies Indiana
> > >> University Bloomington
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >> mei-l mailing list
> > >> mei-l at lists.uni-paderborn.de
> > >> https://lists.uni-paderborn.de/mailman/listinfo/mei-l
> > > _______________________________________________
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> >
> > ---
> > Donald Byrd
> > Woodrow Wilson Indiana Teaching Fellow
> > Adjunct Associate Professor of Informatics Visiting Scientist, Research
> Technologies
> > Indiana University Bloomington
> >
> >
> >
> >
> >
> >
> >
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