This document defines an extension to WCS2.1, namely the extraction of data contained within a polygon defined either by a set of points or the radius and position of a circle point consisting of an information model and an XML encoding for the following two operations:
GetCapabilities - a WCS function that describes the services and operations via a GetCapabilities document.
GetPolygon - a WCS function that supports this operation to extract data from a multidimensional cube that lie within a polygon.
Metadata and vocabularies are defined that provide interoperability of these operations and documents using common semantics. The information model proposed supports MetOcean specific concepts and its user community, but these constructs may be useful and applicable to other communities.
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This document defines an extension to WCS2.1, namely the extraction of data contained within a polygon defined either by a set of points or the radius and position of a circle point consisting of an information model and an XML encoding for the following two operations:
GetCapabilities — a WCS function that describes the services and operations via a GetCapabilities document.
GetPolygon — a WCS function that supports this operation to extract data from a multidimensional cube that lie within a polygon.
Metadata and vocabularies are defined that provide interoperability of these operations and documents using common semantics. The information model proposed supports MetOcean specific concepts and its user community, but these constructs may be useful and applicable to other communities.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.
Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.
No security considerations have been made for this standard.
All questions regarding this submission should be directed to the editor or the submitters:
Name | Affiliation |
---|---|
Peter Trevelyan | Met Office, UK |
Paul Hershberg | National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) |
Steve Olson | National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) |
The purpose of the GetPolygon operation is to extract data contained within a polygon defined either by a set of points or the radius and position of a circle point. The need for the GetPolygon operation stems from active members of the OGC MetOcean Domain Working Group (DWG) who saw a manifest need for extraction of such information from gridded datasets.
This work has been done by members of the OGC MetOcean Domain Working Group.
This standard defines:
An amended GetCapabilities operation response that will list the GetPolygon operation and specify the token in the Sections element of the GetCapabilities request.
A new operation “GetPolygon” that is used to extract data from a multidimensional cube contained within a polygon.
The conformance classes that describe the GetPolygon operation.
Conformance with this standard shall be checked using all the relevant tests specified in Annex A (normative) of this document. The framework, concepts, and methodology for testing, and the criteria to be achieved to claim conformance are specified in the OGC Compliance Testing Policies and Procedures and the OGC Compliance Testing web site[multiblock footnote omitted].
In order to conform to this OGC™ interface standard, a software implementation shall choose to implement:
Any one of the conformance levels specified in Annex A (normative).
All requirements-classes and conformance-classes described in this document are owned by the standard(s) identified.
Requirements and conformance test URIs defined in this document are relative to:
This document establishes the following requirements and conformance classes:-
GetPolygon of URI getPolygon at a conceptual level in clause 8.1
The corresponding conformance class is getPolygon with URI See A.1
PolygonDescriptionRing of defining the PolygonRing at a conceptual level in clause 8.2
The corresponding conformance class is PolygonDescriptionRing with URI . See A.2
PolygonDescriptionCircle of defining the PolygonCircle at a conceptual level in clause 8.3
The corresponding conformance class is PolygonDescription with URI . See A.3
SubsetByTrim of defining the VerticalTemporalDescription at a conceptual level in clause 8.4
The corresponding conformance class is VerticalTemporalDescription with URI . See A.4
SubsetByInterpolation of defining the VerticalTemporalDescription at a conceptual level in clause 8.5
The corresponding conformance class is VerticalTemporalDescription with URI . See A.5
GetPolygon-post-xml of defining the VerticalTemporalDescription at a conceptual level in clause 8.6
The corresponding conformance class is VerticalTemporalDescription with URI seeA.6
For the purposes of this document, the following terms and definitions apply.
This document uses the terms defined in Sub-clause 5.3 of [OGC 06-121r8], which is based on the ISO/IEC Directives, Part 2, Rules for the structure and drafting of International Standards. In particular, the word “shall” (not “must”) is the verb form used to indicate a requirement to be strictly followed to conform to this standard.
This document also uses terms defined in the OGC Standard for Modular specifications (OGC 08-131r3), also known as the ‘ModSpec’. The definitions of terms such as standard, specification, requirement, and conformance test are provided in the ModSpec.
For the purposes of this document, the following additional terms and definitions apply. There is some variation in the specific use of some technical terms within the meteorological domain. We have attempted to follow common usage, referring where possible to the WMO No.306
A numerical weather prediction model is a mathematical model of the atmosphere and oceans used to predict the weather based on current weather conditions and are normally run at set times each day.
Synonyms for numerical weather prediction model: forecast model, NWP Model, simulation
An Example of a numerical weather prediction model: The ECMWF model that runs twice per day and creates a ten day prediction of the global atmosphere.
A typical numerical model simulation has the property of start and end time of the simulation. Intermediate times within the simulation are times for which the data may be used as estimate of the forecast conditions at that time. The use of time within this document does assume that the “Time Dimension” of the simulation falls within the start and end times of the simulation. The standard ISO 8601 notation is used to describe time.
Web Coverage Service (WCS) is an OGC standard that refers to the exchange of geospatial information as ‘coverages’: digital geospatial information representing space-varying phenomena.
The getCapabilities is a WCS operation involving a machine to machine communication. A getCapabilities request to a WCS server returns a list of what operations and services (“capabilities”) are being offered by that server.
A DescribeCoverage is a WCS operation involving a machine-to-machine communication. A DescribeCoverage request to a WCS server returns additional information about a coverage that a client wants to query. Generally speaking, a DescribeCoverage response includes information about the CRS, the metadata, the domain, the range and the formats available. A client generally will need to issue a DescribeCoverage request before it can make the proper GetCoverage request.
A Polygon, in this document, consist of a plane 2D shape with a depth and time dimension. The polygon may be multi-dimensional, and in the case of aviation is often four dimensions, i.e. x, y, z, t.
GetPolygon is a newly proposed MetOcean operation involving a machine to machine communication. A GetPolygon request to a WCS server returns a polygon coverage based on a trajectory path with a lateral and vertical extent (the polygon).
This sections provides details and examples for any conventions used in the document. Examples of conventions are symbols, abbreviations, use of XML schema, or special notes regarding how to read the document.
The normative provisions in this standard are denoted by the URI
All requirements and conformance tests that appear in this document are denoted by partial URIs which are relative to this base.
GML Geography Mark-up Language
O&M Observations and Measurements
OGC Open Geospatial Consortium
MetOcean Meteorological/Oceanographic
NWP Numerical Weather Prediction
SWE OGC Sensor Web Enablement
UML Unified Modelling Language
WCS2.1 OGC Web Coverage Service version 2.1
WMO World Meteorological Organisation
XML W3C Extensible Markup Language
XSD W3C XML Schema Definition Language
The XML implementation specified in this Standard is described using the XML Schema language (XSD) [XML Schema Part 1: Structures, XML Schema Part 2: Datatypes] and Schematron [ISO/IEC 19757-3, Information technology — Document Schema Definition Languages (DSDL) — Part 3: Rule-based validation — Schematron].
The diagrams that appear in this standard are presented using the Unified Modeling Language (UML) static structure diagram.
Note: Within the context of this standard, the following color scheme is used to identify the package in which the class exists. This is just for informative purposes.
Blue: WCS2.1 plus extensions (rsub, scal, int and crs)
Orange: CIS (Coverage Implantation Schema 1.1)
Green: This standard
This standard defines a number of properties that require the use of codes or vocabulary items. In some cases, a list of terms are provided. The MetOcean Profile, on which this builds, has a specific vocabulary provided by the WMO (World Meteorological Office). These vocabularies are concerned with the naming of parameters (variables) used in the rangeSubset element, the coordinate reference systems (aka fixedSurfacetypeAndUnits) used in the srsName attribute, the units of measure, and the significance of time codes. The following table lists the references used within this document.
Code list | Code reference |
---|---|
GRIB edition 2 | |
Discipline | |
Fixed surface types and units | |
Parameter category | |
Parameter number |
The GetPolygon extension for WCS2.1 is an initiative of the MetOcean DWG to enhance the WCS2.1 core profile to extract coverages other than those extracted using the simple SLICE and TRIM methods provided by the core GetCoverage operation shown in Figure 1. For reference to the core WCS2.1 see OGC® Web Coverage Service 2.1 Interface Standard — Core (OGC 17-089r1). This specific extension is designed specifically to extract polygons from multidimensional cubes such as those created by numerical simulations (i.e. NWP) commonly found in the MetOcean community.
The need for this work arises out of the growing need to transfer increasing amounts of data across networks. This can, and should, be done more efficiently by sub-setting the data. This profile specifies how data contained within a polygon may be extracted on the WCS server and transferred to the client. The document also details how the OGC’s WCS2.1 Core is extended to include an additional GetPolygon operation. Finally, the Coverage Implementation Schema (CIS1.1) is used to describe the vertical and temporal definition of the Polygon.
The WCS2.1 files (see
WCS Range Subsetting Extension, version 1.0.0, OGC 12-040
WCS Scaling Extension, version 1.0.0, OGC 12-039
WCS Interpolation Extension, version 1.0.0, OGC 12-049
WCS CRS Extension, version 1.0, OGC 11-053r1
The main benefit of WCS2.1 core to the MetOcean Profile, and specifically the getPolygon operation, is that it allows the description of a CIS1.1 Coverage (see Figure 2). This is important as CIS1.1 supports multi-dimensional coverages and the encoding of coverage types such as polygons.
The term “NWP model” refers to a computer simulation used to forecast the future state of the ocean/atmosphere. A NWP model is normally “run” at a set time and repeated at regular intervals during the day. Each model run has a “Time Dimension” that has “start time”, “end time” and intermediate times. These intermediate times are at set intervals and often referred to as “forecast times”. For each “forecast time”, there will be an estimate of the atmospheric/oceanic conditions for that time. The model start time is a notional time that sets a “base” time for the time intervals. Thus a time interval may have an absolute time e.g. 2017-05-15T00:00:00Z. Or, a time interval may use the start time as reference e.g. PT30H. This signifies a time that is 30 hours ahead of the “start time”.
A “coverage” contains a “DomainSet” component describing the coverage’s domain (i.e. the locations for which values are stored in the coverage) and a “rangeSet” component containing the values of the coverage. A “coverage” also contains a RangeType element that describes the coverage’s range set data structure that consists of one or more fields (also referred to as parameters) that uses the SWE Common [OGC 08-094] DataRecord. The metadata component represents an extensible slot for metadata. The CIS1.1 UML diagram is shown in Figure 2.
A typical NWP forecast is normally a set of 2D rectified grids; although more advanced, grids may be used. A typical model run contains literally thousands of 2D grids and each may described using the CIS1.1 “General Grid” coverage model.
These coverages may described and accessed by using the OGC’s Web Coverage Service (WCS). The main services are “GetCapabilities”, “DescribeCoverage” and “GetCoverage”. A problem with this approach is that the metadata returned by the GetCapabilites response and the number of GetCoverage requests quickly becomes unmanageable. By creating a multidimensional coverage from the 2D coverages, the amount of data and number of GetCoverage requests are greatly reduced, often by a factor of 100.
The key to creating a multidimensional coverage is OGC’s CIS1.1 “Coverage” model. This model makes it much easier to describe the “Domain Set” as a multi-dimensional geometry object.
A typical numerical simulation has a number of different vertical coordinates (i.e. pressure, height above mean sea level, height above ground, surface, and max wind level). By forming a 4D coverage from all of the 2D coverages that share the same horizontal, vertical, and temporal domains, there is a significant reduction in number of coverages, thus reducing complexity. This is a challenge, as the vertical and temporal axes are not regular and need to be enumerated. The “GeneralGridCoverage” as described in CIS1.1 makes this possible.
This key concept therefore changes the traditional view of data as being a set of 2D fields; each with a level, level type, parameter name, and forecast period. We can now describe the whole atmosphere as a multidimensional cube with properties, e.g. temperature, wind speed, and humidity. This results in the ability to make multidimensional (4/5/* D) geospatial queries that are much more efficient, for both the WCS2.1 GetCoverage, GetPolygon and GetCorridor operations. It is important to note that there are special cases where the vertical axis has no vertical dependency (e.g. surface, max wind level). It is also possible that some parameters (e.g. temperature) may belong to more than one coverage (e.g. surface, isobaric, etc.)
A typical polygonal extraction pattern is show in Figure 3 using a set of points to describe the polygon. A special case of a polygon extraction is to use a circle with a radius and centre point position.
Encoding of the polygon in GML is likely to be very verbose and in such cases, a binary format should be used. An alternative to GML e.g. JSON, would however provide a very accessible encoding.
This clause establishes the GetPolygon extension core for conformance class getPolygon. Clients & servers supporting the requirements class support the extraction of a polygon from a multidimensional coverage. A UML diagram of class GetPolygon is shown in Figure 4.
Requirements Class | |
---|---|
Dependency | |
Dependency | |
Requirement 1 | /req/getPolygon/structure A metoceanpolygon:GetPolygon instance shall conform to Figure 4 and |
Requirement 2 |
/req/getPolygon/getCapabilities-response-conformance-class-in-profile A WCS service implementing this extension shall include the following URI in a Profile element in the ServiceIdentification in a GetCapabilities response:
|
Requirement 3 |
/req/getPolygon/request-valid-identifier The coverageId parameter value in a GetPolygon request shall be equal to the identifier of one of the coverages offered by the server addressed. |
Requirement 4 |
/req/getPolygon/acceptable-format If a GetPolygon request contains a format parameter then this parameter shall contain a MIME type identifier occurring in some WCS::formatSupported element of the response to a successful GetCapabilities request to this server. |
Requirement 5 |
/req/getPolygon/acceptable-mediaType If a GetPolygon request contains a mediaType parameter then this parameter shall contain a MIME type identifier of fixed value “multipart/related”. |
Requirement 6 |
/req/getPolygon/polygon-description Check that the Polygon Description element conforms to the requirements classes
|
Requirement 7 |
/req/getPolygon/range-component The parameter value of the RangeComponent of the wcs:RangeItem element shall contain a parameter that is part of the requested coverage. |
Requirement 8 |
/req/getPolygon/response-encoding The contents of the response to a successful GetPolygon request shall be encoded as specified by the request format parameter, if this parameter is present, and in the coverage’s Native Format if this parameter if it is not present. |
Requirement 9 |
/req/getPolygon/PolygonDescription/PolygonRingGeometry The server shall support at least one of the conformance classes i.e.
|
The GetPolygon requirements class defines the structure of the GetPolygon operation.
The new operation GetPolygon allows for the extraction of a polygon. The extra conformance classes are used to further define the possible options outlined here in the getPolygon conformance class. The GetPolygon operation is derived from wcs:GetCoverage and inherits the version and service elements. The GetPolygon properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
metoceanpolygon:polygonDescription | The definition of the extraction pattern (polygon) to be used by the GetPolygon request. | metoceanpolygon:PolygonDescription | One (mandatory) |
metoceanpolygon:verticalTemporalDescription | metoceanpolygon:VerticalTemporalDescription | Zero or One (Optional) |
|
wcs:coverageId | Identifier of a coverage offered by the service on hand | NCName | one (mandatory) |
wcs:mediaType | Optional element indicating the MimeType of the GetCoverage response Only currently allowed valued is “multipart/related”. |
anyURI, fixed to “multipart/related” | zero or one (optional) |
wcs:format | MIME type identifier of the format in which the coverage returned is encoded | anyURI | zero or one (optional) |
rsub:RangeSubset | Selection is based on the coverage’s range type definition where identifiable components are given; in the MetOcean domain, these take the form of defined parameters. | Directly referred to be the GetCorridor element.geItem. | One (mandatory) |
service | The service name. | string=wcs | required |
wcs:extension | Extension element used to hook in additional content e.g. in extensions or application profiles. | Any | One or more |
The RangeSubset properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
rsub:RangeItem | List of range components to be extracted | RangeComponent or RangeInterval | one or more (mandatory) |
rsub:RangeComponent | Range component name | RangeComponent | one (mandatory) |
rusb:RangeInterval | Pair of range interval lower and upper bound | Pair of RangeComponent | one (mandatory) |
The RangeSubset properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
rsub:RangeComponent | Range component name | RangeComponent | one (mandatory) |
This clause establishes the PolygonDescriptionRing requirements class. Clients and servers supporting the requirements class support the extraction of a polygon from a multidimensional data cube using the “PolygonRing” definition of a polygon must conform this requirements class.
Requirements Class | |
---|---|
Dependency | |
Dependency | http://www.opengis.net/gml/3.2 |
Requirement 10 |
/req/getPolygon/PolygonDescriptionRing/structure A metoceanpolygon:PolygonDescription instance shall conform to Figure 5 and, |
Requirement 11 |
/req/getPolygon/PolygonDescriptionRing/Construct The PolygonRing element shall be derived from PolygonGeometry |
Requirement 12 |
/req/getPolygon/PolygonDescriptionRing/containment Only data contained within the polygon shall be included in the result. |
Requirement 13 |
/req/getPolygon/PolygonDescriptionRing/closure The first and last values in the gml:posList element as contained within the gml:LinearRing element shall have the same value. |
The PolygonDescription requirements class defines the structure of the polygon as extracted by the GetPolygon operation. The Polygon may be defined in one of two ways; either be a ring or a circle. The two methods are described as “per Ring” or “per Circle”.
In this clause the polygon will be defined as a set of points to form a ring. The PolygonDescription properties, as per PolygonRing, are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
metoceanpolygon:polygonGeometry | The geometry of the polygon defined as a set of points. | metoceanpolygon:PolygonRing (By substitution) |
One (mandatory) |
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:Polygon | The geometry of the polygon defined as a set of points. | gml:exterior | One (mandatory) |
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:exterior | The direct positions of the polygon points | gml:LinearRing | One (mandatory) |
This clause establishes the PolygonDescriptionCircle requirements class. Clients and servers supporting the requirements class support the extraction of a polygon from a multidimensional coverage using the “PolygonCircle” definition of a polygon, must conform this requirements class..
Requirements Class | |
---|---|
Dependency | |
Dependency | |
Requirement 14 |
/req/getPolygon/PolygonDescriptionCircle/structure A metoceanpolygon:PolygonDescription instance shall conform to Figure 6 and |
Requirement 15 |
/req/getPolygon/PolygonDescriptionCircle/PolygonCircle The PolygonCircle element shall be derived from PolygonGeometry. |
Requirement 16 |
/req/getPolygon/PolygonDescriptionRing/PolygonRing Only data contained within the polygon shall be included in the result. |
In this clause the polygon will be defined as a circle with centre point and radius. The PolygonDescription properties, as per PolygonCircle, are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
metoceanpolygon:polygonGeometry | The geometry of the polygon defined as a centre point and radius | metoceanpolygon:PolygonCircle (By substitution) |
One (mandatory) |
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
The geometry of the polygon defined as a set of points. | gml:Polygon | One (mandatory) |
A Polygon is a special surface that is defined by a single surface . The boundary of this patch is coplanar and the polygon uses planar interpolation in its interior. The elements exterior and interior describe the surface boundary of the polygon. The Polygon properties, as per PolygonCircle, are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:exterior | The specification of the polygon Circle | gml: Ring | One (mandatory) |
A ring is used to represent a single connected component of a surface boundary as specified in ISO 19107:2003, 6.3.6. Every gml:curveMember references or contains one gml:Curve. In the context of a ring, a curve describes the boundary of the surface. The curve is described by referencing one or more gml:segments. The Ring properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:curveMember | Defines the polygon as a set of connected curves | gml: Curve | One or more (mandatory) |
A curve is composed of one or more curve segments. The element gml:segments encapsulates the segments of the curve. The Curve properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:segments | A special case where the segment defines a circle | gml: CircleByCenterPoint | One or more (mandatory) |
A gml:CircleByCenterPoint is a gml:ArcByCenterPoint with identical start and end angle to form a full circle. This representation can be used only in 2D. The CircleByCenterPoint properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
gml:pos | The centre point of the circle. | gml:doubleList | One (mandatory) |
gml:radius | The radius of the circle. | gml:double | One (mandatory) |
This clause establishes the SubsetByTrim conformance class. Clients and servers supporting the requirements class support the extraction of a polygon from a multidimensional data cube and only applies to vertical and temporal extent, if applicable. A UML diagram of class SubSetByTrim is shown in Figure 7. As stated in Section 7.3.1, the vertical and temporal axes are not necessarily regular and thus need to be enumerated. This necessitates using the “CIS::GeneralGridCoverage” as described in CIS1.1, which makes this enumeration possible. A UML diagram of class VerticalTemporalDescription is shown in Figure 6.
Requirements Class | |
---|---|
Dependency | |
Dependency | |
Dependency | |
Requirement 17 |
/req/getPolygon/SubsetByTrim/structure A metoceanpolygon:SubesetByTrim instance shall conform to Figure 7, |
Requirement 18 |
/req/getPolygon/SubsetByTrim/request-valid-dimension + Every dimension value in a GetPolygon Trim request shall be equal to one of the axisLabels dimension names specified in the coverage’s domain set. |
Requirement 19 |
/req/getPolygon/request-no-duplicate-dimension + A GetPolygon request shall contain at most one subsetting operation for each of the dimensions of the coverage addressed. |
Requirement 20 |
/req/getPolygon/SubsetByTrim/Polygon-trim-within-extent Let the extent of the coverage’s CIS::Envelope along the dimension specified in the trim request range from L to H. Then, for the trim bounds trimLow and trimHigh the following shall hold: L ≤ trimLow ≤ trimHigh ≤ H |
The polygon extraction pattern uses a 2D polygon, that is replicated over selected levels in the vertical dimension and selected times in the temporal dimension. These levels and times are selected by “trimming” the MetOcean cube in the vertical and temporal dimensions.
The limits define the upper and lower times and levels to be extracted from the parent MetOcean cube. The extraction, as per the polygon, is only extracted on levels and times from the MetOcean cube that lie between the upper and lower limits. The SubsetByTrim properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
dimensionTrim | Subsetting specifications, at most one per subsetting dimension | DimensionTrim | One (mandatory) |
The DimensionTrim properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
dimension | Name of dimension along which to subset | string | One or more (mandatory) |
trimLow | Lower bound of cutout along dimension | string | One (mandatory) |
trimHigh | Upper bound of cutout along dimension | string | One (mandatory) |
This clause establishes the SubsetByInterpolation conformance class. Clients and servers supporting the requirements class support the extraction of a polygon from a multidimensional coverage that has a vertical and temporal extent by interpolating the data to a defined vertical/temporal axes. A UML diagram showing the SubsetByInterpolation class is shown in Figure 8.
Requirements Class | |
---|---|
Dependency | |
Dependency | |
Dependency | |
Dependency | |
Dependency | |
Dependency | . |
Requirement 21 |
/req/getPolygon/SubsetByInterpolation/structure A metoceanpolygon:VerticalTemporalDescription instance shall conform to Figure 8 and |
Requirement 22 |
/req/getPolygon/SubsetByInterpolation/grid-order In a coverage using the grid-irregular scheme, the directPosition values in any CIS::IrregularAxis shall be listed in strictly monotonic order, expressed in the units of measure of this axis as defined in the CRS identified in the srsName item of the envelope. |
Requirement 23 |
/req/getPolygon/SubsetByInterpolation/disjoint In a GetPolygon request using the grid-irregular scheme, for any two CIS::DisplacementAxisNest elements their set of axis names shall be disjoint, i.e. they have no elements in common. |
Requirement 24 |
/req/getPolygon/SubsetByInterpolation/valid-interpolation-method The interpolations methods used in the interpolation shall be thosw offered by the server |
This conformance class describes how a grid (target grid) is defined onto which the data contained within the polygon is extracted by interpolation. The “target” grid is only defined in the vertical and temporal dimensions as there is no interpolation in the horizontal. Thus the grid points will not be interpolated in the horizontal domain, but will be in the vertical and temporal dimensions.
The SubsetByInterpolation properties are shown in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
metoceanpolygon:interpolation | Interpolation method to be applied to the named axis GetPolygon result preparation | int:IntInterpolation | One (mandatory) |
metoceanpolygon:generalGrid | Lays foundation for the modelling of all possible grid types in CIS. | cis:GeneralGrid | One (mandatory) |
The Interpolation properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
int:globalInterpolation | The default Interpolation method to be used | int:IntInterpolationPerAxis | One (mandatory) |
The InterpolationPerAxis properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
int:axis | The axis for which the interpolation Method will be applied | anyURI | One (mandatory |
interpolationMethod | The interpolation method. | anyURI | One (mandatory |
Describing the direct positions in multi-dimensional coordinate space, depending on the type of grid. The GeneralGrid properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
srsName | URL identifying the Index CRS of the domain set grid array in this coverage | anyURI | One (mandatory) |
axisLabels | Axes involved in the “nest” of displaced direct positions; these axes shall form a subset of the CIS::GeneralGrid axisLabels | NCName | One or more (mandatory) |
cis:GridLimits | In addition, the limits of the underlying array are given by the CIS::gridLimits component | cis:IndexAxis | Zero or one (optional) |
cis:Axis | grid axis identifiers, all distinct within a grid | cis:axisLabel | One or more (mandatory) |
cis:DisplacementAxisNest | DisplacementAxisNest combines several axes to a single “nest” where the co-ordinates are enumerated individually for each direct position. | cis:DisplacementAxisNestType | One or more (mandatory) |
The CIS::DisplacementAxisNest combines several axes to a single “nest” where the coordinates are enumerated individually for each direct position. The properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
axisLabels | Axes involved in the “nest” of displaced direct positions; these axes shall form a subset of the CIS::GeneralGrid axisLabels | cis:NameListType | One or more |
uomLabels | cis:NameListType | cis:NameListType | One or more |
directPositions | Array of direct positions along this axis, linearized according to the sequence rule or, if missing, along the GML 3.2.1 default | string | One or more (mandatory) |
gml:sequenceRule | Description of the array linearization in directPositions, according to the GML 3.2.1 sequence rule | GML:: sequenceRuleEnumeration |
Zero or one (optional) |
The grid limits in the CIS::Axis structure contains information about the grid boundaries in the coverage’s CRS. The GridLimits properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
srsName | URL identifying the Index CRS of the domain set grid array in this coverage | anyURI | One (mandatory) |
cis:indexAxis | all axes of the Index CRS referenced in srsName, in proper sequence | CIS:: IndexAxis |
One or more (mandatory) |
axisLabels | Axes involved in the “nest” of displaced direct positions; these axes shall form a subset of the CIS::GeneralGrid axisLabels | string | One or more (mandatory) |
The Axis properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
axisLabel | identifier of this axis | NCName | One |
The IndexAxis properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
lowerBound | Lowest array coordinate along this axis | anySimpleType | One (mandatory) |
upperBound | Highest array coordinate along this axis | anySimpleType | One (mandatory) |
axisLabel | identifier of this axis | NCName | One |
The RegularAxis properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
lowerBound | Lowest coordinate along this grid axis | anySimpleType | One (mandatory) |
upperBound | Highest coordinate along this axis | anySimpleType | One (mandatory) |
resolution | grid resolution along this axis | anySimpleType | One (mandatory) |
uomLabel | Shorthand identifier of the Unit of Measure used on this axis (as indicated in the CRS definition for this axis) | NCName | One (mandatory) |
axisLabel | identifier of this axis | NCName | One |
The IrregularAxis properties are listed in
Name | Definition | Data types and values | Multiplicity |
---|---|---|---|
directPositions | Ordered sequence of direct positions along this axis | cis::DirectPositionType | One or more (mandatory) |
uomLabel | unit of measure in which values along this axis are expressed | string | One (mandatory) |
This requirements class specifies how the GetPolygon operation is provided in WCS servers that implement the HTTP/POST using XML request body protocol binding.
Requirements Class | |
---|---|
Dependency | |
Dependency | WCS 2.1 protocol extension XML-POST [OGC 09-148r1] |
Requirement 25 |
/req/getPolygon-post-xml/mandatory Implementations of this GetPolygon extension that support the GetPolygon post-xml requirements class shall support the WCS 2.1 protocol extension XML-POST [OGC 09-148r1]. |
Requirement 26 |
/req/ GetPolygon-post-xml/conformance-class-in-profile Implementations of this GetPolygon extension that support the GetPolygon-xml-post requirements class shall include the following URI in a Profile element in the ServiceIdentification in a GetCapabilities response:
|
Requirement 27 |
/req/getPolygon-post-xml/GetPolygon-request-structure A WCS server implementing the XML/POST protocol binding extension shall encode request body of the GetPolygon operation using an XML document of type metocean:GetPolygon and described in this document |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | ||
Test | /conf/getPolygon/structure | |
Requirement 1 |
/req/getPolygon/structure | |
Test purpose | A metoceanpolygon:GetPolygon instance shall conform to Figure 4 and |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/getCapabilities-response-conformance-class-in-profile | |
Requirement 2 |
/req/getPolygon/getCapabilities-response-conformance-class-in-profile | |
Test purpose | A WCS service implementing this extension shall include the following URI in a Profile element in the ServiceIdentification in a GetCapabilities response: http://www.opengis.net/spec/WCS_application-profile_metocean_polygon/1.0 /conf/getPolygon |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/request-valid-identifier | |
Requirement 3 |
/req/getPolygon/request-valid-identifier | |
Test purpose |
The coverageId parameter value in a GetPolygon request shall be equal to the identifier of one of the coverages offered by the server addressed. |
|
Test method |
Send a GetPolygon request to the service under test. For every listed CoverageId (either in the GetCapabilities response or DescribeCoverageCollection response ) then send, for each coverage identifier listed, a valid GetPolygon request. Check that none of these requests results in an exception. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/acceptable-format | |
Requirement 4 |
/req/getPolygon/acceptable-format | |
Test purpose |
If a GetPolygon request contains a format parameter then this parameter shall contain a MIME type identifier occurring in some WCS::formatSupported element of the response to a successful GetCapabilities request to this server. |
|
Test method | Send GetCapabilities request to server under test, remember Capabilities document returned. Send GetPolygon requests containing valid coverage identifiers to server under test. Vary the format parameter:
Pass test if all checks succeed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/acceptable-mediaType | |
Requirement 5 |
/req/getPolygon/acceptable-mediaType | |
Test purpose |
If a GetPolygon request contains a mediaType parameter then this parameter shall contain a MIME type identifier of fixed value “multipart/related”. |
|
Test method | Send a GetPolygon request containing a mediaType parameter. Vary this parameter value:
Pass test if all checks succeed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/polygon-description | |
Requirement 6 |
/req/getPolygon/polygon-description | |
Test purpose | Check that the Polygon Description element conforms to the requirements classes
|
|
Test method | Send a GetPolygon request containing and invalid Polygon Description element and verify that request fails. Pass test if all checks succeed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/range-component | |
Requirement 7 |
/req/getPolygon/range-component | |
Test purpose | Send DescribePolygon request to server under test, for a valid coverage and for each coverage note the RangeType items returned in the response document. Send GetPolygon requests containing the RangeItems and check for a valid response. Pass test if all checks succeed. |
|
Test method | ||
Test type |
Conformance |
|
Test | /conf/getPolygon/response-encoding | |
Requirement 8 |
/req/getPolygon/response-encoding | |
Test purpose |
The contents of the response to a successful GetPolygon request shall be encoded as specified by the request format parameter, if this parameter is present, and in the coverage’s Native Format if this parameter if it is not present. |
|
Test method | For each coverage encoding format (i.e., format encoding extension) supported by the server under test: Send a valid GetPolygon request to retrieve a coverage in this format. Check that the result is a valid instance of the format indicated. Pass test if all checks succeed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescription/PolygonRingGeometry | |
Requirement 9 |
/req/getPolygon/PolygonDescription/PolygonRingGeometry | |
Test purpose | The server shall support at least one of the conformance classes i.e.
|
|
Test method |
Determine the list of supported extensions via a valid GetCapabilities request; check that there is at least one protocol extension listed. |
|
Test type |
Conformance |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | ||
Test | /conf/getPolygon/PolygonDescriptionRing/structure | |
Requirement 10 |
/req/getPolygon/PolygonDescriptionRing/structure | |
Test purpose | A metoceanpolygon:PolygonDescription instance shall conform to Figure 5 and, |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescriptionRing/construct | |
Requirement 11 |
/req/getPolygon/PolygonDescriptionRing/construct | |
Test purpose |
The PolygonRing element shall be derived from PolygonGeometry |
|
Test method |
Check the structure of the GetPolygon request element PolygonGeometry |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescriptionRing/containment | |
Requirement 12 |
/req/getPolygon/PolygonDescriptionRing/containment | |
Test purpose |
Only data contained within the polygon shall be included in the result. |
|
Test method |
Send a GetPolygon request to the service under test using PolygonDescriptionRing, check that response is correct. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescriptionRing/Closure | |
Requirement 13 |
/req/getPolygon/PolygonDescriptionRing/closure | |
Test purpose |
The first and last values in the gml:posList element as contained within the gml:LinearRing element shall have the same value. |
|
Test method |
Submit a GetPolygon request with a incomplete gml:LinearRing and check the correct error is returned. |
|
Test type |
Conformance |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | http://www.opengis.net/gml/3.2 | |
Test | /conf/getPolygon/PolygonDescriptionCircle/structure | |
Requirement 14 |
/req/getPolygon/PolygonDescriptionCircle/structure | |
Test purpose | A metoceanpolygon:PolygonDescription instance shall conform to Figure 6 and |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescriptionCircle/PolygonCircle | |
Requirement 15 |
/req/getPolygon/PolygonDescriptionCircle/PolygonCircle | |
Test purpose |
The PolygonCircle element shall be derived from PolygonGeometry. |
|
Test method |
Check the structure of the GetPolygon request element PolygonGeometry |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/PolygonDescriptionRing/PolygonRing | |
Requirement 16 |
/req/getPolygon/PolygonDescriptionRing/PolygonRing |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | ||
Dependency | ||
Test | /conf/getPolygon/SubsetByTrim/structure | |
Requirement 17 |
/req/getPolygon/SubsetByTrim/structure | |
Test purpose | A metoceanpolygon:SubsetByTrim instance shall conform to Figure 7, |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/SubsetByTrim/request-valid-dimension | |
Requirement 18 |
/req/getPolygon/SubsetByTrim/request-valid-dimension | |
Test purpose |
Every dimension value in a GetPolygon Trim request shall be equal to one of the axisLabels dimension names specified in the coverage’s domain set. |
|
Test method |
Send an invalid GetPolygon request to server under test that does have not have axisLabels dimension names specified and check for the appropriate exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/request-no-duplicate-dimension | |
Requirement 19 |
/req/getPolygon/request-no-duplicate-dimension | |
Test purpose |
A GetPolygon request shall contain at most one subsetting operation for each of the dimensions of the coverage addressed. |
|
Test method |
Send an invalid GetPolygon request to server under test that does have duplicate dimension and check for the appropriate exception. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/SubsetByTrim/Polygon-trim-within-extent | |
Requirement 20 |
/req/getPolygon/SubsetByTrim/Polygon-trim-within-extent | |
Test purpose |
Let the extent of the coverage’s CIS::Envelope along the dimension specified in the trim request range from L to H. Then, for the trim bounds trimLow and trimHigh the following shall hold: L ≤ trimLow ≤ trimHigh ≤ H |
|
Test method |
Send an invalid GetPolygon request to server under test that does have a valid TRIM bound and check for an exception.. |
|
Test type |
Conformance |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | ||
Dependency | ||
Dependency | ||
Dependency | ||
Test | /conf/getPolygon/SubsetByInterpolation/structure | |
Requirement 21 |
req/getPolygon/SubsetByInterpolation/structure | |
Test purpose | A metoceanpolygon:VerticalTemporalDescription instance shall conform to Figure 8 and |
|
Test method |
Send a valid GetPolygon request to server under test which conforms to the references in the requirement. Check that the response is not an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/SubsetByInterpolation/grid-order | |
Requirement 22 |
/req/getPolygon/SubsetByInterpolation/grid-order | |
Test purpose |
In a coverage using the grid-irregular scheme, the directPosition values in any CIS::IrregularAxis shall be listed in strictly monotonic order, expressed in the units of measure of this axis as defined in the CRS identified in the srsName item of the envelope. |
|
Test method |
Send an invalid GetPolygon request to server under test that does not conform to this requirement and check for an exception. |
|
Test Type |
Conformance |
|
Test | /conf/getPolygon/SubsetByInterpolation/grid-order | |
Requirement 23 |
/req/getPolygon/SubsetByInterpolation/disjoint | |
Test purpose |
In a GetPolygon request using the grid-irregular scheme, for any two CIS::DisplacementAxisNest elements their set of axis names shall be disjoint, i.e. they have no elements in common. |
|
Test method |
Send an invalid GetPolygon request to server under test that does not conform to this requirement and check for an exception. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon/SubsetByInterpolation/valid-interpolation-method | |
Requirement 24 |
/req/getPolygon/SubsetByInterpolation/valid-interpolation-method | |
Test purpose |
The interpolations methods used in the interpolation shall be those offered by the server as listed in the GetCapabilities response contained in the InterpolationMetadata element. |
|
Test method |
In a GetPolygon request using the check for an invalid response if an Interpolation method is used that is not advertised in the GetCapabilites response. |
|
Test type |
Conformance |
Conformance Class | ||
---|---|---|
Requirements | ||
Dependency | ||
Dependency | WCS 2.1 protocol extension XML-POST [OGC 09-148r1] | |
Test | /conf/getPolygon-post-xml/mandatory | |
Requirement 25 |
/req/getPolygon-post-xml/mandatory | |
Test purpose |
Implementations of this GetPolygon extension that support the GetPolygon post-xml requirements class shall support the WCS 2.1 protocol extension XML-POST [OGC 09-148r1]. |
|
Test method |
Determine the list of supported extensions via a valid GetCapabilities request; check that the extension required is listed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon-post-xml/conformance-class-in-profile | |
Requirement 26 |
/req/getPolygon-post-xml/conformance-class-in-profile | |
Test purpose | Implementations of this GetPolygon extension that support the GetPolygon-post-xml requirements class shall include the following URI in a Profile element in the ServiceIdentification in a GetCapabilities response:
|
|
Test method |
Determine the list of supported extensions via a valid GetCapabilities request; check that the extension required is listed. |
|
Test type |
Conformance |
|
Test | /conf/getPolygon-post-xml/GetPolygon-request-structure | |
Requirement 27 |
/req/getPolygon-post-xml/GetPolygon-request-structure | |
Test purpose |
A WCS server implementing the XML/POST protocol binding extension shall encode request body of the GetPolygon operation using an XML document of type metocean:GetPolygon and described in this document. |
|
Test method |
Send syntactically legal and illegal GetCoverage request to server under test, verify that the server responds appropriately. |
|
Test type |
Conformance |
Date | Release | Editor | Primary clauses modified | Description |
---|---|---|---|---|
2017-08-21 | 0.1 | Trevelyan/Hershberg/Olson | all | Created |
2018-11-21 | 0.2 | Trevelyan/Hershberg/Olson | all |
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.