[MEI-L] Coordinate system confusion [and terminology]
David Lewis
D.Lewis at gold.ac.uk
Tue Jul 11 11:55:30 CEST 2017
Just as a side note – and I don't think that anyone here is suggesting this – the danger of making direct use of a term like `diatonic step' (rather than just mentioning it in the guidelines) is that there are notations that do use staff-lines, but for which a half-space step is not a diatonic step. Many tablatures fall into this category.
David
> On 10 Jul 2017, at 12:35, Laurent Pugin <lxpugin at gmail.com> wrote:
>
> I personally do not see using "half-space" as a unit as an improvement. Why would the unit by half-something? I would be in favour of keeping "virtual unit" / "vu" and simply add a statement in the guidelines that the unit corresponds to a diatonic step or half the space between to staff lines.
>
> On Sun, Jul 9, 2017 at 5:15 PM, Klaus Rettinghaus <klaus.rettinghaus at gmail.com> wrote:
> I strongly recommend to stick with virtual unit! Talking about space could lead to the assumption that it's about the space _between_ two lines. But as a line by itself has a defined width, a space would merely be "the space between two adjacent staff lines plus the width of one staff line, which is confusing.
>
> The Guidelines are already very precise about that:
> "A single vu is half the distance between the vertical center point of a staff line and that of an adjacent staff line."
>
> And after all, a "vu" isn't just about musical context, i.e. "things" on or around a staff, but a real (relative) measurement unit for the whole layout.
>
> --
> Klaus
>
>
>
> Am Sa, 8. Jul, 2017 um 9:55 schrieb Roland, Perry D. (pdr4h) <pdr4h at eservices.virginia.edu>:
>
> If there's support from the community, I'm fine with changing "vu" to "hs". If we're going to break it, let's break it now.
> In the schema and Guidelines, it's a simple search-and-replace. Changes to existing markup can be built into the version 3 to version 4 XSLT. But I can't speak to changes to Verovio and other MEI-based software, so if there are objections from developers, speak now please.
>
> --
> p.
>
> -----Original Message-----
> From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf Of Byrd, Donald A.
> Sent: Saturday, July 08, 2017 3:34 PM
> To: Music Encoding Initiative <mei-l at lists.uni-paderborn.de>
> Subject: Re: [MEI-L] Coordinate system confusion [and terminology]
>
> I understand the issue. But I think just saying "half-STEPS/diatonic steps" instead of "half-
> spaces/diatonic steps" and half-spaces (hs for short) instead of virtual units (vu for short)
> would do the job. No need to change the unit, just the term.
>
> Thanks for listening! I'll shut up now.
>
> --DAB
>
>
> On Jul 8, 2017, at 3:12 PM, "Roland, Perry D. (pdr4h)" <pdr4h at eservices.virginia.edu>
> wrote:
>
> >
> > Don,
> >
> > Like I said before, changing MEI's unit of measurement from half-spaces/diatonic steps
> to spaces would break all existing markup and software. Changing the markup is
> reasonably easy, but modifying software is another problem all together. So, unless there's
> a HUGE outcry from the community, I'd prefer to leave things as they are.
> >
> > --
> > p.
> >
> >
> >> -----Original Message-----
> >> From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf Of Byrd, Donald
> A.
> >> Sent: Saturday, July 08, 2017 2:48 PM
> >> To: Music Encoding Initiative <mei-l at lists.uni-paderborn.de>
> >> Subject: Re: [MEI-L] Coordinate system confusion [and terminology]
> >>
> >> Before my original suggestion is completely forgotten, I'd like to
> >> back up a little. Perry, you said
> >>>
> >>> 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.
> >>
> >> Gould and Read rarely if ever saying anything like "2-1/2
> >> half-spaces"; the example I gave, and what they actually say, is "2-1/2 SPACES". And
> the fact the "spaces"
> >> terminology is used consistently by both in works intended for
> >> practical use seems like pretty good evidence that that terminology doesn't bother
> people much.
> >>
> >> Let's see, here's a random note in a random piece of music; I wonder how long its stem
> is?
> >> Ah, it extends all the way across three spaces and halfway across
> >> another! :-). It's a standard one-octave stem, with a length of 3 and 1/2 spaces.
> >>
> >> --Don
> >>
> >>
> >> On Jul 7, 2017, at 4:41 PM, "Roland, Perry D. (pdr4h)"
> >> <pdr4h at eservices.virginia.edu>
> >> wrote:
> >>
> >>> Yes, 1 vu = 1 diatonic step. However, the phrase “diatonic step”
> >>> doesn’t actually appear in the definition –
> >>>
> >>> “A single vu is half the distance between the vertical center point
> >>> of a staff line and that
> >> of an adjacent staff line.”
> >>>
> >>> Even this definition occurs within the description of @vu.height.
> >>> This is definitely a
> >> place where the Guidelines could use some work.
> >>>
> >>> --
> >>> p.
> >>>
> >>>
> >>> From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf
> >>> Of Craig Sapp
> >>> Sent: Friday, July 07, 2017 2:58 PM
> >>> To: Music Encoding Initiative <mei-l at lists.uni-paderborn.de>
> >>> Subject: Re: [MEI-L] Coordinate system confusion [and terminology]
> >>>
> >>>> 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
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>
> >>>>
> >>>>
> >>> _______________________________________________
> >>
> >>
> >>
> >>
> >> _______________________________________________
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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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