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Re: Best Practice for encoding spatial coverage

From: Frans Knibbe <frans.knibbe@geodan.nl>
Date: Fri, 19 Jun 2015 11:55:06 +0200
Message-ID: <CAFVDz42aZoJhKhdop5gjpdZ5RgozQBOFsLNudjsoBPbbGS0yMQ@mail.gmail.com>
To: "Mcgibbney, Lewis J (398M)" <Lewis.J.Mcgibbney@jpl.nasa.gov>
Cc: SDW WG Public List <public-sdw-wg@w3.org>
Hi all,

Based on suggestions from Josh and Andrea I have come to the following
example of how to express the spatial extent of a data set (in Turtle
notation, without blank nodes):

ex:myDataset
dcterms:spatial ex:myExtent .

ex:myExtent
a dcterms:Location ;
schema:box "50 4 52 6" .

To me this seems a nice and simple solution, based on very common
vocabularies. For a web developer this gives a direct link from the dataset
URI to the numbers he/she needs for configuring the web application.

The expression 'schema:box "50 4 52 6"' could be replaced (or accompanied)
by 'georss:box "50 4 52 6"', but I assume the schema.org vocabulary is more
widely used than the GeoRSS vocabulary, and more likely to be already
included in the set of referenced vocabularies. On the other hand,
schema.org also allows  'schema:box "50,4 52,6"', i.e. commas between
latitude and longitude, while GeoRSS only allows whitespace. Having
multiple possibilities for the format of the text literal is less web
developer friendly, I think.

What do you think? Do we already have something that we can recommend as a
best practice?

Greetings,
Frans


2015-06-18 5:10 GMT+02:00 Mcgibbney, Lewis J (398M) <
Lewis.J.Mcgibbney@jpl.nasa.gov>:

>   Hi Frans,
>
>
>  I have just had a talk with a web developer on the best way of making
> the extent of a spatial data set known, in a Linked Data context. It is
> useful to know the spatial extent of a data set because that way a map can
> be zoomed in on the right patch of Earth.
>
>
>    I would like to throw in an example of some data and metadata used to
> described it which I use on a day-to-day basis.
>   The data is from Landsat 7’s Enhanced Thematic Mapper (ETM+) instrument
> and is in HDF4-EOS manifestation with the XML metadata looking like the
> paste of XML at the end of this message.
> You will see the <bounding_coordinates> node but will also note that image
> corner locations are defined within the <corner> nodes with referenced
> locations being provisioned for UL (upper left) and LR (lower right)
> respectively.
> I’m enjoying seeing the wealth of vocabulary choices being provided by the
> group, so I wanted to make sure that my use case is also considered.
> Thanks
>
>  <?xml version="1.0" encoding="UTF-8"?>
>
>  <espa_metadata version="1.1"
> xmlns="http://espa.cr.usgs.gov/v1.1"
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:schemaLocation="http://espa.cr.usgs.gov/v1.1
> http://espa.cr.usgs.gov/schema/espa_internal_metadata_v1_1.xsd">
>
>      <global_metadata>
>         <data_provider>USGS/EROS</data_provider>
>         <satellite>LANDSAT_7</satellite>
>         <instrument>ETM</instrument>
>         <acquisition_date>2015-05-09</acquisition_date>
>         <scene_center_time>18:38:53.331477Z</scene_center_time>
>
> <level1_production_date>2015-05-09T20:01:30Z</level1_production_date>
>         <solar_angles zenith="27.388939" azimuth="136.141678"
> units="degrees"/>
>         <wrs system="2" path="43" row="33"/>
>
> <lpgs_metadata_file>LE70430332015129EDC00_MTL.txt</lpgs_metadata_file>
>         <corner location="UL" latitude="39.878930"
> longitude="-121.497290"/>
>         <corner location="LR" latitude="37.918700"
> longitude="-118.804970"/>
>         <bounding_coordinates>
>             <west>-121.536923</west>
>             <east>-118.692020</east>
>             <north>39.879064</north>
>             <south>37.918558</south>
>         </bounding_coordinates>
>         <projection_information projection="UTM" datum="WGS84"
> units="meters">
>             <corner_point location="UL" x="628500.000000"
> y="4415400.000000"/>
>             <corner_point location="LR" x="868800.000000"
> y="4205100.000000"/>
>             <grid_origin>CENTER</grid_origin>
>             <utm_proj_params>
>                 <zone_code>10</zone_code>
>             </utm_proj_params>
>         </projection_information>
>         <orientation_angle>0.000000</orientation_angle>
>     </global_metadata>
>
>      <bands>
>         <band product="sr_refl" source="toa_refl" name="sr_band1"
> category="image" data_type="INT16" nlines="7011" nsamps="8011"
> fill_value="-9999" saturate_value="20000" scale_factor="0.000100"
> add_offset="0.000000">
>             <short_name>LE7SR</short_name>
>             <long_name>band 1 surface reflectance</long_name>
>             <file_name>LE70430332015129EDC00_sr_band1_hdf.img</file_name>
>             <pixel_size x="30" y="30" units="meters"/>
>             <resample_method>none</resample_method>
>             <data_units>reflectance</data_units>
>             <valid_range min="-2000" max="16000"/>
>             <calibrated_nt>5.000000</calibrated_nt>
>             <app_version>LEDAPS_2.2.1</app_version>
>             <production_date>2015-05-12T17:44:56Z</production_date>
>         </band>
>      <band …>
>     </…>
> </…
>



-- 
Frans Knibbe
Geodan
President Kennedylaan 1
1079 MB Amsterdam (NL)

T +31 (0)20 - 5711 347
E frans.knibbe@geodan.nl
www.geodan.nl
disclaimer <http://www.geodan.nl/disclaimer>
Received on Friday, 19 June 2015 09:55:36 UTC

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