17.9 WCS Extensions Implemented

This topic describes the WCS Extensions implemented and gives examples of some elements defined by each extension.

It concludes with a GetCoverage request example that includes all the extensions.

11-053r1 OGC Web Coverage Service Interface Standard – CRS Extension

This WCS CRS Extension defines how to request and obtain a coverage in CRSs different from the Native CRS, and also how to provide a subsetting bounding box with coordinates in a CRS different from the Native CRS. A WCS server supporting this WCS CRS Extension announces the CRSs supported by listing their CRS Identifiers in its Capabilities document. For example:

<wcscrs:subsettingCrs>http://www.opengis.net/def/crs/EPSG/0/4326</wcscrs:subsettingCrs>
<wcscrs:outputCrs>http://www.opengis.net/def/crs/EPSG/0/4326</wcscrs:outputCrs>

112-039 OGC Web Coverage Service Interface Standard – Scaling Extension

This extension allows scaling of a coverage along one or more of its axes during its server-side processing in a GetCoverage request. For example:

<scal:ScaleByFactor>
 <scal:axis>E</scal:axis>
  <scal:scaleFactor>0.5</scal:scaleFactor>
</scal:ScaleByFactor>

112-040 OGC Web Coverage Service Interface Standard – Range Subsetting Extension

This extension allows extraction of specific fields, according to the range type specification, from the range set of a coverage during server-side processing of a coverage in a GetCoverage request. For example:

<rsub:RangeSubset>
	<rsub:RangeItem>
		<rsub:RangeComponent>band1</rsub:RangeComponent>
	</rsub:RangeItem>
	<rsub:RangeItem>
		<rsub:RangeInterval>
			<rsub:startComponent>band3</rsub:startComponent>
			<rsub:endComponent>band5</rsub:endComponent>
		</rsub:RangeInterval>
	</rsub:RangeItem>
</rsub:RangeSubset>

112-049 OGC Web Coverage Service Interface Standard – Interpolation Extension

This extension gives control over interpolation of a coverage during its server-side processing.

This allows the WCS client to control and specify the interpolation mechanism to be applied to a coverage during server processing. For example:

<int:Interpolation>
  <int:globalInterpolation>
    http://www.opengis.net/def/interpolation/OGC/1/nearest-neighbor
  </int:globalInterpolation>
</int:Interpolation>

112-100r1 OGC GML Application Schema – Coverages – GeoTIFF Coverage Encoding Profile

This encoding profile specifies the usage of the GeoTIFF data format for the encoding of GML coverages. For example:

<wcs:format>image/tiff</wcs:format>

Example Showing All Extensions

The following is an example of a GetCoverage request example with all extensions included:

<wcs:GetCoverage xmlns:wcs="http://www.opengis.net/wcs/2.0"
  xmlns:gml="http://www.opengis.net/gml/3.2"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.opengis.net/wcs/2.0 http://schemas.opengis.net/wcs/2.0/wcsAll.xsd"
  xmlns:scal="http://www.opengis.net/wcs/scaling/1.0"
  xmlns:wcscrs="http://www.opengis.net/wcs/service-extension/crs/1.0"
  xmlns:rsub="http://www.opengis.net/wcs/rangesubsetting/1.0"
  xmlns:int="http://www.opengis.net/wcs/interpolation/1.0"
  service="WCS" version="2.0.1">
  <wcs:Extension>
    <wcscrs:subsettingCrs>http://www.opengis.net/def/crs/EPSG/0/4326</wcscrs:subsettingCrs>
    <wcscrs:outputCrs>http://www.opengis.net/def/crs/EPSG/0/4326</wcscrs:outputCrs>
    <rsub:RangeSubset>
      <rsub:RangeItem>
        <rsub:RangeComponent>L3</rsub:RangeComponent>
      </rsub:RangeItem>
    </rsub:RangeSubset>
    <int:Interpolation>
      <int:globalInterpolation>
        http://www.opengis.net/def/interpolation/OGC/1/nearest-neighbor
      </int:globalInterpolation>
    </int:Interpolation>
    <scal:ScaleByFactor>
      <scal:scaleFactor>0.5</scal:scaleFactor>
    </scal:ScaleByFactor>
  </wcs:Extension>
  <wcs:CoverageId>C0005</wcs:CoverageId>
  <wcs:DimensionSlice>
    <wcs:Dimension>N</wcs:Dimension>
    <wcs:SlicePoint>8.16270027015798</wcs:SlicePoint>
  </wcs:DimensionSlice>
  <wcs:DimensionTrim>
    <wcs:Dimension>E</wcs:Dimension>
    <wcs:TrimLow>112.990337346209</wcs:TrimLow>
    <wcs:TrimHigh>113.028655200765</wcs:TrimHigh>
  </wcs:DimensionTrim>
  <wcs:format>image/tiff</wcs:format>
  <wcs:mediaType>multipart/related</wcs:mediaType>
</wcs:GetCoverage>