W3C home > Mailing lists > Public > public-sdw-wg@w3.org > September 2016

Re: updates to the Best Practice document

From: Jeremy Tandy <jeremy.tandy@gmail.com>
Date: Thu, 08 Sep 2016 12:00:34 +0000
Message-ID: <CADtUq_1_sBMTej6Vb=_L7OssojX5Hz6LxwHEu4SXAi=+D4_oMw@mail.gmail.com>
To: Simon.Cox@csiro.au, public-sdw-wg@w3.org
Thank you! I reference ISO 19109 from the coverage definition in the
glossary (although I've not set up the bibliographic ref yet) so it should
be credited in the bibliography.

Jeremy
On Thu, 8 Sep 2016 at 12:58, <Simon.Cox@csiro.au> wrote:

> You've largely paraphrased and only directly used a couple of sentences,
> so unlikely to be a problem. If in doubt, give credit - ie add it to the
> bibliography.
>
> ------------------------------
> *From:* Jeremy Tandy <jeremy.tandy@gmail.com>
> *Sent:* Thursday, 8 September 2016 9:50:19 AM
> *To:* Cox, Simon (L&W, Clayton); public-sdw-wg@w3.org
> *Subject:* Re: updates to the Best Practice document
>
> All- I've tried to incorporate some of the useful text cited by Simon.
> I've also taken the opportunity to update the definition of coverage in the
> glossary.
>
> On Thu, 8 Sep 2016 at 07:24 Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>
>> Hi Simon- That's useful ... what's the copyright associated with the ISO
>> text?
>> On Thu, 8 Sep 2016 at 04:43, <Simon.Cox@csiro.au> wrote:
>>
>>> The recent revision of ISO 19109 added material on Coverages (as well as
>>> Observations) that was not in the original, recognising that coverages are
>>> important tools for some applications. You might also like to consider
>>> these sections from ISO 19109:2013
>>>
>>>
>>>
>>> 7.2.2 Coverages
>>>
>>>
>>>
>>> Many aspects of the real-world may be represented as features whose
>>> properties are single-valued and static. These conventional features
>>> provide a model of the world in terms of discrete objects located in it.
>>> However, in some applications it is more useful to use a model focussing on
>>> the variation of property values in space and time, formalized as
>>> coverages. Users of geographic information may utilize both viewpoints.
>>> While coverages are themselves strictly features as well, it is common to
>>> contrast coverages and non-coverage features when discussing the
>>> functionality provided by each viewpoint. In the following discussion the
>>> name ‘feature’ refers to non-coverage features.
>>>
>>> 
>>>
>>> The feature and coverage representations may be related in several ways:
>>>
>>>
>>>
>>> — signal processing to find and characterize features: signals in
>>> coverages may provide evidence for the existence, location and type of
>>> features, detected through modelling and interpretation;
>>>
>>>
>>>
>>> EXAMPLE 1 Patterns of colour or other radiance bands within a
>>> remotely-sensed image may be used to infer the existence of specific
>>> objects or features on the ground.
>>>
>>>
>>>
>>> EXAMPLE 2 Signals in a geophysical borehole log may be used to infer the
>>> presence of particular rock-units at underground locations.
>>>
>>>
>>>
>>> — coverage-typed feature properties: feature properties whose value vary
>>> within the scope of a feature may be described as coverages whose domain
>>> extent is the geometry of the feature;
>>>
>>>
>>>
>>> EXAMPLE 3 The variation of concentration of a particular ore-mineral
>>> within a mine may be described as a spatial function or coverage within the
>>> spatial limits of the mine.
>>>
>>>
>>>
>>> — features sample a coverage: the values of a common property of a set
>>> of features provide a discrete sampling of a coverage, whose range type is
>>> the property, and whose domain is the aggregate geometry of the set of
>>> features.
>>>
>>>
>>>
>>> EXAMPLE 4 The temperature at a set of weather stations may be compiled
>>> to show the spatial variation of temperature across the region where the
>>> stations are located.
>>>
>>>
>>>
>>> A constraint in the latter two cases is that a property-type from a
>>> feature catalogue is the range-type of a coverage description in the same
>>> universe of discourse.
>>>
>>>
>>>
>>> The case of features having property values that vary within the scope
>>> of the feature can be described using the general feature model (7.5.8).
>>>
>>>
>>>
>>> While the coverage model is described in detail in ISO 19123, an
>>> application schema may include both feature- and coverage-types.
>>>
>>> NOTE The feature and coverage viewpoints are related to (though not
>>> identical with) the so-called ‘vector’ and ‘raster’ approaches from
>>> traditional GIS implementations.
>>>
>>>
>>>
>>> Then, immediately following:
>>>
>>>
>>>
>>> 7.2.3 Properties and observations
>>>
>>>
>>>
>>> Property values are associated with features and coverages. In the case
>>> of features, a property value is associated with a classified object. In
>>> the case of coverages, a property value is associated with a position in
>>> the domain.
>>>
>>>
>>>
>>> Later
>>>
>>>
>>>
>>> 8.8 Rules for use of coverage functions
>>>
>>>
>>>
>>> Coverage functions are used to describe characteristics of real-world
>>> phenomena that vary over space and/or time. Typical examples are
>>> temperature, elevation and precipitation. A coverage contains a set of such
>>> values, each associated with one of the elements in a spatial, temporal or
>>> spatio-temporal domain. Typical spatial domains are point sets (e.g. sensor
>>> locations), curve sets (e.g. contour lines), grids (e.g. orthoimages,
>>> elevation models), etc. A property whose value varies as a function of time
>>> may be represented as a temporal coverage or time-series. A continuous
>>> coverage is associated with a method for interpolating values at spatial
>>> positions between the elements of a domain, e.g. between two points or
>>> contour lines.
>>>
>>>
>>>
>>> *From:* Jeremy Tandy [mailto:jeremy.tandy@gmail.com]
>>> *Sent:* Thursday, 8 September 2016 7:17 AM
>>> *To:* SDW WG Public List <public-sdw-wg@w3.org>
>>> *Subject:* updates to the Best Practice document
>>>
>>>
>>>
>>> Following today's BP call, I've now added into the BP doc what I was
>>> talking about:
>>>
>>>
>>>
>>> * A section explaining about Coverages [1] (thanks to Jon Blower; I
>>> repurposed one of his Melodies blog posts!)
>>>
>>> * The beginnings of a section that tries to provide a linear path
>>> through the decisions you might make when publishing data: "How to use
>>> these best practices" [2] ... this tries to combine SDW and DWBP best
>>> practices into a coherent whole ... that said, I've found it really hard to
>>> plan this out; I think it's working (& there's more in my head that I
>>> unfortunately don't have time to write before I disappear tomorrow ...
>>> leaving no more time for update before TPAC.
>>>
>>>
>>>
>>> Hope these additions are worthwhile.
>>>
>>>
>>>
>>> Jeremy
>>>
>>>
>>>
>>> [1]: http://w3c.github.io/sdw/bp/#coverages
>>>
>>> [2]: http://w3c.github.io/sdw/bp/#how-to-use
>>>
>>
Received on Thursday, 8 September 2016 12:01:46 UTC

This archive was generated by hypermail 2.4.0 : Thursday, 24 March 2022 20:31:26 UTC