wcsDescribeCoverage.xsd 2010-02-01 http://schemas.opengis.net/wcs/1.1.0/gml4wcs.xsd This XML Schema Document defines the DescribeCoverage operation request and response XML elements and types, used by the OGC Web Coverage Service (WCS). WCS is an OGC Standard. Copyright (c) 2006,2010 Open Geospatial Consortium, Inc. All Rights Reserved. To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ . Request to a WCS to perform the DescribeCoverage operation. This operation allows a client to retrieve descriptions of one or more coverages. In this XML encoding, no "request" parameter is included, since the element name specifies the specific operation. Unordered list of identifiers of desired coverages. A client can obtain identifiers by a prior GetCapabilities request, or from a third-party source. Response from a WCS DescribeCoverage operation, containing one or more coverage descriptions. Full description of one coverage available from a WCS server. This description shall include sufficient information to allow all valid GetCoverage operation requests to be prepared by a WCS client. Unambiguous identifier of this coverage, unique for this WCS server. Optional unordered list of more metadata elements about this coverage. A list of metadata elements for CoverageDescriptions could be specified in a WCS Application Profile. Unordered list of references to all the coordinate reference systems in which GetCoverage operation requests and responses can be encoded for this coverage. Unordered list of identifiers of all the formats in which GetCoverage operation responses can be encoded for this coverage. Definition of the spatial-temporal domain of a coverage. The Domain shall include a SpatialDomain (describing the spatial locations for which coverages can be requested), and should included a TemporalDomain (describing the time instants or intervals for which coverages can be requested). Although optional, the TemporalDomain should be included whenever a value is known or a useful estimate is available. Definition of the spatial domain of a coverage. Unordered list of bounding boxes whose union covers the spatial domain of this coverage. One bounding box could simply duplicate the information in the ows:WGS84BoundingBox in the CoverageSummary; but the intent is to describe the spatial domain in more detail (e.g., in several different CRSs, or several rectangular areas instead of one overall bounding box). This bounding box shall use the ImageCRS of the stored coverage when that coverage is not georeferenced and not georectified. Notice that WCS use of this BoundingBox is further specified in specification Subclause 7.5. Definition of GridCRS of the stored coverage. This GridCRS shall be included when this coverage is georectified and is thus stored in a GridCRS. The definition of the GridCRS of a stored georectified coverage is included to inform clients of this GridCRS, for possible use in a GetCoverage operation request. Georeferencing coordinate transformation for unrectified coverage, which should be included when available for a coverage that is georeferenced but not georectified. To support use cases 4, 5, 9, and/or 10 specified in Annex H, a WCS server needs to use a georeferencing coordinate transformation for a georeferenced but not georectified coverage. That georeferencing transformation can be specified as a Transformation, or a ConcatenatedOperation that includes at least one Transformation. However, a WCS server may not support those use cases, not use a georeferencing transformation specified in that manner, or not make that transformation available to clients. Association to ImageCRS of the stored coverage. This ImageCRS shall be included when this coverage is an image. The ImageCRS for an image coverage is referenced to inform clients of the ImageCRS, for possible use in a GetCoverage operation request. The definition of this ImageCRS shall be included unless the association reference URI completely specifies that ImageCRS (such as by using the URL of the definition or using a suitable URN). Unordered list of polygons whose union covers the spatial domain of this coverage. Polygons are particularly useful for areas that are poorly approximated by a BoundingBox (such as satellite image swaths, island groups, other non-convex areas). Association to an image coordinate reference system, either referencing or containing the definition of that reference system. Definition of the temporal domain of a coverage, the times for which valid data are available. The times should to be ordered from the oldest to the newest. Defines the fields (categories, measures, or values) in the range records available for each location in the coverage domain. Each such field may be a scalar (numeric or text) value, such as population density, or a vector (compound or tensor) of many similar values, such as incomes by race, or radiances by wavelength. Each range field is typically an observable whose meaning and reference system are referenced by URIs. Unordered list of the Fields in the Range of a coverage. Description of an individual field in a coverage range record. Identifier of this Field. These field identifiers shall be unique in one CoverageDescription. Further definition of this field, including meaning, units, etc. In this Definition, the AllowedValues should be used to encode the extent of possible values for this field, excluding the Null Value. If the range is not known, AnyValue should be used. Unordered list of the values used when valid Field values are not available for whatever reason. The coverage encoding itself may specify a fixed value for null (e.g. “–99999” or “N/A”), but often the choice is up to the provider and must be communicated to the client outside the coverage itself. Each null value shall be encoded as a string. The optional codeSpace attribute can reference a definition of the reason why this value is null. Spatial interpolation method(s) that server can apply to this field. One of these interpolation methods shall be used when a GetCoverage operation request requires resampling. When the only interpolation method listed is ‘none’, clients may only retrieve coverages from this coverage in its native CRS at its native resolution. Unordered list of the axes in a vector field for which there are Field values. This list shall be included when this Field has a vector of values. Notice that the axes can be listed here in any order; however, the axis order listed here shall be used in the KVP encoding of a GetCoverage operation request (TBR). Definition of one axis in a field for which there are a vector of values. This type is largely a subset of the ows:DomainType as needed for a range field axis. Meaning metadata, which should be referenced for this axis. Data type metadata, which may be referenced for this axis. Unit of measure, which should be included when this axis has units or a more complete reference system. Optional unordered list of other metadata elements about this axis. A list of required and optional other metadata elements for this quantity can be specified in a WCS Application Profile. Name or identifier of this axis. List of all the available (valid) key values for this axis. For numeric keys, signed values should be ordered from negative infinity to positive infinity. Valid key value for this axis. There will normally be more than one key value for an axis, but one is allowed for special circumstances.