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Re: Requirements for units of measure, accuracy and precision

From: Frans Knibbe <frans.knibbe@geodan.nl>
Date: Mon, 26 Sep 2016 16:19:31 +0200
Message-ID: <CAFVDz41TyjoTVjmi=Q-XuUbiWRuK5YZafafo9Zpv6OyjPk6tcw@mail.gmail.com>
To: "public-sdw-wg@w3.org" <public-sdw-wg@w3.org>
Hello all,

Issue-74 was closed at the F2F meeting in Lisbon. The UoM part is handled
by addition of a note to the CRS definition requirement
<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#CRSDefinition>.
For precision, a new requirement was added: Coordinate precision
<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#CoordinatePrecision>
.

Regards,
Frans



On 9 September 2016 at 14:41, Frans Knibbe <frans.knibbe@geodan.nl> wrote:

> First, I would like to note that this issue is now an ISSUE. It is UCR
> ISSUE-74 <https://www.w3.org/2015/spatial/track/issues/74>, to be
> precise. I hope this message sufficiently links this thread to the issue.
>
> The issue states that UoM and accuracy should be covered in the UCR and BP
> documents, and be respected in other deliverables too. Can we start with
> properly addressing the topics in the UCR document? Hopefully that gives
> some direction to the way best practices should be set up too.
>
> I would like to repeat proposals made in the first message of this thread:
>
> 1)  We expand CRS definition
> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#CRSDefinition> requirement
> a bit to make it clear that a CRS definition should include an indication
> of UoM. For instance:
> "There should be a recommended way of referencing a Coordinate Reference
> System (CRS) with a HTTP URI, and to get useful data about the CRS when
> that URI is dereferenced. The CRS data should include the unit of
> measurement of the CRS."
>
> 2) We add a new requirement:
> "The use of precision that matches uncertainty in coordinate data should
> be facilitated and encouraged"
>
> Would those things suffice as far as the UC&R go?
>
> Regards,
> Frans
>
>
>
>
>
>
> On 6 September 2016 at 08:08, Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>
>> Hi. We already do provide a link with in the BP doc to this ... See :
>> http://w3c.github.io/sdw/bp/#desc-accuracy
>>
>> That said, it's buried there too. Seems that UoM (and other
>> record/property level metadata) is deserving of its own BP?
>>
>> Jeremy
>>
>>
>>
>> On Tue, 6 Sep 2016 at 00:33, Byron Cochrane <bcochrane@linz.govt.nz>
>> wrote:
>>
>>> That was buried! I think it would be useful to provide a link in SDWBP
>>> to this (https://www.w3.org/TR/vocab-dqv/#ExpressDatasetAccuracyPrec
>>> ision) if we hope for others to find this guidance.
>>>
>>> Cheers,
>>> Byron
>>>
>>> -----Original Message-----
>>> From: Simon.Cox@csiro.au [mailto:Simon.Cox@csiro.au]
>>> Sent: Tuesday, 6 September 2016 11:14 a.m.
>>> To: andrea.perego@jrc.ec.europa.eu; frans.knibbe@geodan.nl;
>>> jeremy.tandy@gmail.com
>>> Cc: rob@metalinkage.com.au; jlieberman@tumblingwalls.com;
>>> chris.little@metoffice.gov.uk; public-sdw-wg@w3.org
>>> Subject: RE: Requirements for units of measure, accuracy and precision
>>>
>>> Thanks Andrea -
>>>
>>> But gosh - you have to dig deep to find it. And the sub-head 'dataset
>>> precision and accuracy' does not exactly shout 'units of measure' or
>>> 'scale' does it? It looks like a side-effect rather than a central concern.
>>>
>>> Am frankly amazed that this issue is not more central for quantitative
>>> data, which is a significant subset of general 'data on the web'.
>>>
>>> Simon
>>>
>>> -----Original Message-----
>>> From: Andrea Perego [mailto:andrea.perego@jrc.ec.europa.eu]
>>> Sent: Monday, 5 September 2016 7:15 PM
>>> To: Frans Knibbe <frans.knibbe@geodan.nl>; Jeremy Tandy <
>>> jeremy.tandy@gmail.com>
>>> Cc: Rob Atkinson <rob@metalinkage.com.au>; Joshua Lieberman <
>>> jlieberman@tumblingwalls.com>; Chris Little <
>>> chris.little@metoffice.gov.uk>; Cox, Simon (L&W, Clayton)
>>> <Simon.Cox@csiro.au>; public-sdw-wg@w3.org
>>> Subject: Re: Requirements for units of measure, accuracy and precision
>>>
>>> Just to note that UoMs are included in some of the examples of DQV, in
>>> particular in relation to spatial resolution - see:
>>>
>>> https://www.w3.org/TR/vocab-dqv/#ExpressDatasetAccuracyPrecision
>>>
>>> For more details, see my earlier messages on this topics [1,2].
>>>
>>> Please note that the examples above are some of those added by the DWBP
>>> WG following our comments on the "representation of precision and accuracy"
>>> - see thread starting here:
>>>
>>> https://lists.w3.org/Archives/Public/public-sdw-comments/201
>>> 6Mar/0001.html
>>>
>>> and related DWBP issue:
>>>
>>> https://www.w3.org/2013/dwbp/track/issues/243
>>>
>>>
>>> Since DWBP deliverables include UoMs only for spatial resolution, I
>>> think it's up to us to address the other relevant use cases - possibly by
>>> building upon the DQV approach, if appropriate.
>>>
>>> Andrea
>>>
>>> ----
>>> [1]https://lists.w3.org/Archives/Public/public-sdw-wg/2016Jul/0164.html
>>> [2]https://lists.w3.org/Archives/Public/public-sdw-wg/2016Jul/0253.html
>>>
>>>
>>> On 02/09/2016 17:26, Frans Knibbe wrote:
>>> > All,
>>> > thanks for replying, and a special thanks to Rob for fencing off
>>> > Jeremy's hijack attempt :-)
>>> >
>>> > An attempt to summarize and suggest steps to be taken:
>>> >
>>> >   * One of us could submit a comment to the DWBPWG that we feel
>>> >     indication of UoM and uncertainty in quantitative data deserves
>>> >     attention in their document. Is there a volunteer?
>>> >     (I would like to note that an earlier DWBP comment had me
>>> suggesting
>>> >     they should encourage data providers using significant digits,
>>> which
>>> >     can be seen a good way to meet the requirement for indicating
>>> >     uncertainty in quantitative data. After some discussion, the DWBP
>>> >     decided the subject was out of scope for data on the web (see this
>>> >     message
>>> >     <https://lists.w3.org/Archives/Public/public-dwbp-comments/
>>> 2016Jun/0012.html>),
>>> >     because it applies to the broader domain of quantitative data (that
>>> >     can exist outside of the Web too). So I think next to the DWBP
>>> >     already being fixed there is little chance of the comment being
>>> >     acted upon.)
>>> >   * There seems to be agreement that the UoM thing should be tied to
>>> CRS
>>> >     definitions. Can we solve the issue by listing an indication of UoM
>>> >     as one of the types of 'useful information' about a CRS in the CRS
>>> >     Definition requirement
>>> >     <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequiremen
>>> ts.html#CRSDefinition>?
>>> >     Of course I would need to list some other typical properties of
>>> CRSs
>>> >     for good measure, but that should not be a problem.
>>> >   * We add a BP requirement to the UC&R that says "The use of precision
>>> >     that matches uncertainty in coordinate data should be facilitated
>>> >     and encouraged". Note that we already havea requirement for
>>> >     describing spatial resolution in the metadata
>>> >     <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequiremen
>>> ts.html#SpatialMetadata>.
>>> >
>>> > I hope we can agree on making concrete changes to the UCR document (or
>>> > not) soon.
>>> >
>>> > Greetings,
>>> > Frans
>>> >
>>> >
>>> > On 1 September 2016 at 13:41, Jeremy Tandy <jeremy.tandy@gmail.com
>>> > <mailto:jeremy.tandy@gmail.com>> wrote:
>>> >
>>> >     @ Rob:
>>> >
>>> >     > I think we need to step back and decide if this is about
>>> >     requirements or BP
>>> >
>>> >     Good point. I'll take the best practice question to a separate
>>> >     thread ...
>>> >
>>> >     On Wed, 31 Aug 2016 at 23:44 Rob Atkinson <rob@metalinkage.com.au
>>> >     <mailto:rob@metalinkage.com.au>> wrote:
>>> >
>>> >
>>> >         I think we need to step back and decide if this is about
>>> >         requirements or BP, and target the elements of conversation
>>> >         better to which deliverable is affected.
>>> >
>>> >         IMHO there is a _requirement_ for a canonical mechanism to
>>> state
>>> >         aspects of spatial properties.
>>> >         I also think its a requirement for that mechanism to be common
>>> >         with broader requirements for publishing metadata.  Its not a
>>> >         uniquely spatial concern - but spatial is typified by this
>>> being
>>> >         relevant at dataset, service, feature and property levels of
>>> >         granularity and the need for users to be able to discover and
>>> >         interpret this information regardless of where it is best
>>> placed.
>>> >
>>> >         If there is no consensus on an identifiable Best Practice -
>>> IMHO
>>> >         we should note this as an unmet requirement in the BP document
>>> ,
>>> >         and refer to the catch-all (reuse something!) BP
>>> >
>>> >         Rob
>>> >
>>> >
>>> >
>>> >
>>> >         On Thu, 1 Sep 2016 at 02:27 Joshua Lieberman
>>> >         <jlieberman@tumblingwalls.com
>>> >         <mailto:jlieberman@tumblingwalls.com>> wrote:
>>> >
>>> >             Jeremy,
>>> >
>>> >             These may not be the terms we want to make a best practice
>>> >             of. Precision (closeness of repeated measurements) and
>>> >             accuracy (closeness to truth) are really concepts that are
>>> >             impossible to compute directly, since one can’t either make
>>> >             all possible repeated measurements, nor actually make true
>>> >             measurements. What one can estimate and report is
>>> >             uncertainty (the range within which the true value has some
>>> >             likelihood of occurring if we accounted for all sources of
>>> >             error) and resolution (predicted precision or fineness of
>>> >             measurement).
>>> >
>>> >             The spatial question in this is whether one should report
>>> >             multidimensional uncertainty and resolution, using such
>>> >             things as error ellipses or fuzzy geometric boundaries. It
>>> >             could be a real mess to make a map with fuzzy topographic
>>> >             contours, but the variation in hypsometric uncertainty
>>> >             between different published maps would probably shock
>>> people
>>> >             if they were made aware of it.
>>> >
>>> >             Josh
>>> >
>>> >>             On Aug 31, 2016, at 11:13 AM, Jeremy Tandy
>>> >>             <jeremy.tandy@gmail.com <mailto:jeremy.tandy@gmail.com>>
>>> >>             wrote:
>>> >>
>>> >>             Ignoring the UoM thing for now (although I can see @josh's
>>> >>             point about it being needed to define CRS), can folks tell
>>> >>             me whether BP 5 "Describe the positional accuracy of
>>> >>             spatial data" [1] is on the right track to meet
>>> >>             requirements about precision and accuracy? If not, please
>>> >>             can one of you fine folks make some suggests content
>>> changes?
>>> >>
>>> >>             Thanks in advance. Jeremy
>>> >>
>>> >>             [1]: http://w3c.github.io/sdw/bp/#desc-accuracy
>>> >>             <http://w3c.github.io/sdw/bp/#desc-accuracy>
>>> >>
>>> >>             On Wed, 31 Aug 2016 at 12:32 Joshua Lieberman
>>> >>             <jlieberman@tumblingwalls.com
>>> >>             <mailto:jlieberman@tumblingwalls.com>> wrote:
>>> >>
>>> >>                 Given that there are specific spatial aspects to both
>>> >>                 precision and uom, for example a precision ellipsoid
>>> >>                 is a geometry and a unit of measure such as an
>>> >>                 altitude is relatively to a datum such as a geoid, it
>>> >>                 seems reasonable to me that these can be included SDW
>>> >>                 BP's without worrying overmuch whether DWBP will ever
>>> >>                 get to these sorts of multi-dimensional and affine
>>> >>                 space issues.
>>> >>
>>> >>                 Josh
>>> >>
>>> >>                 Joshua Lieberman, Ph.D.
>>> >>                 Principal, Tumbling Walls Consultancy
>>> >>                 Tel/Direct: +1 617-431-6431 <tel:%2B1%20617-431-6431>
>>> >>                 jlieberman@tumblingwalls.com
>>> >>                 <mailto:jlieberman@tumblingwalls.com>
>>> >>
>>> >>                 On Aug 31, 2016, at 07:19, Little, Chris
>>> >>                 <chris.little@metoffice.gov.uk
>>> >>                 <mailto:chris.little@metoffice.gov.uk>> wrote:
>>> >>
>>> >>>                 Simon, Rob,____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 I support submitting a formal public comment to DWBP,
>>> >>>                 AND doing something specific to spatial.____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 Chris____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 *From:*Rob Atkinson [mailto:rob@metalinkage.com.au]
>>> >>>                 *Sent:* Friday, August 26, 2016 1:42 AM
>>> >>>                 *To:* Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au
>>> >;
>>> >>>                 frans.knibbe@geodan.nl
>>> >>>                 <mailto:frans.knibbe@geodan.nl>;
>>> public-sdw-wg@w3.org
>>> >>>                 <mailto:public-sdw-wg@w3.org>
>>> >>>                 *Subject:* Re: Requirements for units of measure,
>>> >>>                 accuracy and precision____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 When this was raised and we asked Phil for guidance,
>>> >>>                 we were basically told DWBP is pretty much fixed, if
>>> >>>                 we care it behooves us to address it even ifs its a
>>> >>>                 more general issue. I think we just need to note its
>>> >>>                 a more general issue, and provide what we feel is a
>>> >>>                 BP otherwise there is really no useful path to
>>> >>>                 implementation.____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 Given precision is a first class concern of spatial
>>> >>>                 data - as spatial resolution is going to be ever
>>> >>>                 critical in the Internet of Things especially, we
>>> >>>                 need to handle this.  Precision may be common to a
>>> >>>                 dataset due to a common methodology, specific to a
>>> >>>                 sensor, or time-varying - such as GPS coordinates.
>>> >>>                 The BP needs to address how to attach this at this
>>> >>>                 different levels of granularity. We need to cover
>>> >>>                 both measured position and gridded coverages as well,
>>> >>>                 and preferably not with completely different
>>> >>>                 approaches. Precision is not generally an attribute
>>> >>>                 of a CRS, unless we are going to define CRS for every
>>> >>>                 possible grid - and that would be a fairly major
>>> >>>                 departure from existing practice i suspect.____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 UoM is a _similar_ case, and not inherently spatial,
>>> >>>                 so i agree it can be localised to CRS , TRS,  but I
>>> >>>                 see no harm in tying it in to the same pattern as
>>> >>>                 spatial precision - whats needed is a BP to provide
>>> >>>                 metadata about values, to meet the hard requirement
>>> >>>                 of spatial CRS and precision, but its useful to
>>> >>>                 suggest this would be applicable to UoM. Certainly
>>> >>>                 having a completely different set of patterns for
>>> >>>                 attribution of uom and CRS feels like sub-optimal
>>> >>>                 practice. ____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 Rob____
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 __ __
>>> >>>
>>> >>>                 On Fri, 26 Aug 2016 at 10:09 <Simon.Cox@csiro.au
>>> >>>                 <mailto:Simon.Cox@csiro.au>> wrote:____
>>> >>>
>>> >>>                     Ø  The lack of information on units of measure
>>> >>>                     and the apparent lack of concern for proper
>>> >>>                     indication of uncertainty in numbers are
>>> >>>                     widespread in spatial data and something should
>>> >>>                     definitely be done about that. However, I
>>> >>>                     maintain that both problems are more general than
>>> >>>                     spatial data and are therefore out of scope for
>>> >>>                     the UCR document. We have tried hard to limit the
>>> >>>                     UCR requirements to only spatial data on the
>>> >>> web.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Frans – I agree with this assessment in
>>> >>>                     principle. Should we try to pass it back up to
>>> >>>                     the DWBP group? ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Best Practice 7
>>> >>>                     https://www.w3.org/TR/dwbp/#quality
>>> >>>                     <https://www.w3.org/TR/dwbp/#quality> refers off
>>> >>>                     to the Data Quality Vocabulary, which may mean
>>> >>>                     they think it is dealt with, but I’m not
>>> >>>                     convinced. It’s one more step away from the
>>> >>>                     readers, at least, and none of the examples show
>>> >>>                     units of measure, or suggest where they would be
>>> >>>                     found. ‘units’ or ‘uom’ does not appear in their
>>> >>>                     document (in the sense that we mean, anyway).
>>> >>> ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     However, this document is still in ‘Working
>>> >>>                     Draft’ status, although it is certainly a pretty
>>> >>>                     mature document by now. We could start by making
>>> >>>                     a comment on their public list
>>> >>>                     https://lists.w3.org/Archives
>>> /Public/public-dwbp-comments/
>>> >>>                     <https://lists.w3.org/Archive
>>> s/Public/public-dwbp-comments/>
>>> >>>                     to the effect that ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     ‘The requirement to know the units of measure for
>>> >>>                     quantitative data (or another kind of ‘reference
>>> >>>                     system’ for other kinds of data values) is not
>>> >>>                     mentioned in https://www.w3.org/TR/dwbp/. Units
>>> >>>                     are required in order to use quantitative data,
>>> >>>                     so the Data on the Web Best Practices should
>>> >>>                     include a recommendation on the topic. This
>>> >>>                     affects the following benefit categories:
>>> >>>                     Comprehension (C), Processability (P), Reuse (R)’
>>> >>>                     ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     But perhaps this is a place where some more
>>> >>>                     formal coordination between the groups is
>>> >>>                     warranted? ____
>>> >>>
>>> >>>                     @phila – has this issue ever been discussed in
>>> >>>                     the DWBP group? A quick search of the email
>>> >>>                     archive doesn’t turn anything up. ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     --____
>>> >>>
>>> >>>                     As a side comment – it is kinda remarkable how
>>> >>>                     this gets overlooked. I raised it in the Open
>>> >>>                     Knowledge forum on their Data
>>> >>>                     Packaging/Frictionless Data initiative. As soon
>>> >>>                     as I mentioned it there was acceptance that it is
>>> >>>                     in scope, but somehow no-one had brought it up
>>> >>>                     until then. ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Simon ____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     *From:*Frans Knibbe
>>> >>>                     [mailto:frans.knibbe@geodan.nl
>>> >>>                     <mailto:frans.knibbe@geodan.nl>]
>>> >>>                     *Sent:* Thursday, 25 August 2016 10:50 PM
>>> >>>                     *To:* SDW WG Public List <public-sdw-wg@w3.org
>>> >>>                     <mailto:public-sdw-wg@w3.org>>____
>>> >>>
>>> >>>
>>> >>>                     *Subject:* Requirements for units of measure,
>>> >>>                     accuracy and precision____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Hello,____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     In messages
>>> >>>                     https://lists.w3.org/Archives
>>> /Public/public-sdw-wg/2016Aug/0172.html
>>> >>>                     <https://lists.w3.org/Archive
>>> s/Public/public-sdw-wg/2016Aug/0172.html>
>>> >>>                     and ____
>>> >>>
>>> >>>                     https://lists.w3.org/Archives
>>> /Public/public-sdw-wg/2016Aug/0109.html
>>> >>>                     <https://lists.w3.org/Archive
>>> s/Public/public-sdw-wg/2016Aug/0109.html>
>>> >>>                     the possibility of adding new requirements to the
>>> >>>                     UC&R doc was brought forward. Those should be
>>> >>>                     requirements that____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     A) the units of measure (UoM) in spatial data
>>> >>>                     should be made clear____
>>> >>>
>>> >>>                     B) the precision of spatial data should be made
>>> >>>                     clear____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     From the looks of it, those requirements would at
>>> >>>                     least be requirements for the BP
>>> >>> deliverable.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     The topic was also discussed in the last SSN
>>> >>>                     teleconference
>>> >>>                     <https://www.w3.org/2016/08/23-sdwssn-minutes>.
>>> I
>>> >>>                     thought it would be good to create a separate
>>> >>>                     thread for these related issues.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     I will first repeat my initial response: The
>>> >>>                     requirements are very good requirements. The lack
>>> >>>                     of information on units of measure and the
>>> >>>                     apparent lack of concern for proper indication of
>>> >>>                     uncertainty in numbers are widespread in spatial
>>> >>>                     data and something should definitely be done
>>> >>>                     about that. However, I maintain that both
>>> >>>                     problems are more general than spatial data and
>>> >>>                     are therefore out of scope for the UCR document.
>>> >>>                     We have tried hard to limit the UCR requirements
>>> >>>                     to only spatial data on the web. This constraint
>>> >>>                     is specifically mentioned in the section on
>>> >>>                     methodology
>>> >>>                     <http://w3c.github.io/sdw/Use
>>> Cases/SDWUseCasesAndRequirements.html#Methodology>.
>>> >>>                     If we were to neglect this constraint, then the
>>> >>>                     amount of requirements could run out of hand
>>> >>>                     quickly, the decisions on which requirements to
>>> >>>                     include or not would become very arbitrary and
>>> >>>                     the deliverable teams that are tasked with
>>> >>>                     meeting requirements would inevitably find out
>>> >>>                     that they are not in a position to meet the
>>> >>>                     requirements because they are not in scope for
>>> >>>                     their work. Of course the deliverable teams will
>>> >>>                     work with additional requirements next to the
>>> >>>                     ones mentioned in the UCR document. Those
>>> >>>                     additional requirements will be based on general
>>> >>>                     best practices. I think the UoM and precision
>>> >>>                     requirements fall in that class.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     That said, perhaps there is a way to shape the
>>> >>>                     requirements in such a way that they can be
>>> >>>                     included in the UCR document, without violating
>>> >>>                     the spatial scope constraint too harshly. After
>>> >>>                     all, it has been done for other requirements too,
>>> >>>                     to be honest.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Let's start with the UoM requirement (A). I
>>> >>>                     assume that is about the UoM of coordinate data
>>> >>>                     only. I think this is already implicitly covered
>>> >>>                     by the CRS requirements Linking geometry to CRS
>>> >>>                     <http://w3c.github.io/sdw/Use
>>> Cases/SDWUseCasesAndRequirements.html#LinkingCRS>,
>>> >>>                     Determinable CRS
>>> >>>                     <http://w3c.github.io/sdw/Use
>>> Cases/SDWUseCasesAndRequirements.html#DeterminableCRS>
>>> >>>                     and CRS definition
>>> >>>                     <http://w3c.github.io/sdw/Use
>>> Cases/SDWUseCasesAndRequirements.html#CRSDefinition>:
>>> >>>                     If those requirements are met, it should always
>>> >>>                     be possible to know the UoM of coordinates,
>>> >>>                     because the UoM will be part of the CRS
>>> >>>                     definition. Perhaps we should be explicit in
>>> >>>                     mentioning that a CRS definition should include
>>> >>>                     an indication of UoM?____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     As for the requirement B, if we change the
>>> >>>                     wording a bit the requirement could be made
>>> >>>                     applicable to spatial data only and therefore be
>>> >>>                     in scope:____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     B2) The use of precision that matches uncertainty
>>> >>>                     in coordinate data should be facilitated and
>>> >>>                     encouraged____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     With this kind of wording I think the BP editors
>>> >>>                     have a fighting chance of meeting the
>>> >>>                     requirement.____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Please share your thoughts...____
>>> >>>
>>> >>>                      ____
>>> >>>
>>> >>>                     Regards,____
>>> >>>
>>> >>>                     Frans____
>>> >>>
>>> >
>>> >
>>>
>>> --
>>> Andrea Perego, Ph.D.
>>> Scientific / Technical Project Officer
>>> European Commission DG JRC
>>> Directorate B - Growth and Innovation
>>> Unit B6 - Digital Economy
>>> Via E. Fermi, 2749 - TP 262
>>> 21027 Ispra VA, Italy
>>>
>>> https://ec.europa.eu/jrc/
>>>
>>> ----
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>>> Commission.
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>>
>
Received on Monday, 26 September 2016 14:20:14 UTC

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