Re: Best Practice for encoding spatial coverage

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 …>
    </…>
</…