[MEI-L] Coordinate system confusion [and terminology]
Laurent Pugin
lxpugin at gmail.com
Mon Jul 10 13:35:29 CEST 2017
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
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>
>>> >>>>>>
>>> >>>>>>
>>> >>>>>>
>>> >>>>>>
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>> _______________________________________________
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> _______________________________________________
>>> >> mei-l mailing list
>>> >> mei-l at lists.uni-paderborn.de
>>> >> https://lists.uni-paderborn.de/mailman/listinfo/mei-l
>>> > _______________________________________________
>>> > mei-l mailing list
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>>>
>>> ---
>>> 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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